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Building Bigger Roads Makes Traffic Worse

212 points by data_scientist 12y ago

melling 12y ago
They're also an eyesore. Not to worry, over the next several decades large cities will build out effective mass transit systems. High-speed rail will eventually come to America after years of debate. Look to China to lead the way. What's this low-speed maglev that they're building now? http://usa.chinadaily.com.cn/epaper/2014-02/19/content_17291903.htm http://usa.chinadaily.com.cn/epaper/2014-02/19/content_17291...
- pdonis 12y ago
  over the next several decades large cities will build out effective mass transit systems Which, as the article points out, won't fix the traffic congestion, because as some people switch from driving to mass transit, other people will take their place by driving when they previously walked or just didn't make the trip at all. So mass transit can increase the total number of trips made, but it won't decrease road usage.
  - personZ 12y ago
    http://www.theonion.com/articles/report-98-percent-of-us-commuters-favor-public-tra,1434/ http://www.theonion.com/articles/report-98-percent-of-us-com... It is the onion, and is flippant, but as a general belief it touches upon a basic truth -- everyone would love if everyone else used public transit, leaving the roads available for our use.
    - _delirium 12y ago
      This is occasionally used as an argument in favor of cheaper or free public transit: that even from a self-interest perspective, it makes sense for road users to subsidize public transit, as a way of effectively paying other people to get off the roads and out of their way. However most road users don't seem to see it that way.
    - TheCoelacanth 12y ago
      As with most articles from the Onion, there is an element of truth, but if you look at a city with good public transit options (NYC is the only one in the US) over 50% of commuters travel by public transit. If you look at cities with adequate but not great public transit options (DC, Boston or San Francisco) more than 30% of commuters travel by public transit.
  - tormeh 12y ago
    People like me, who use mass transit, don't care about traffic congestion. Queue all you want. I just want more mass transit because travel by mass transit happens in constant time regardless of the amount of travelers (within reasonable bounds. Carriages do get full eventually).
    - martinald 12y ago
      The other benefit is being able to do something useful on the commute too. I can usually get through all my morning's emails on the train into work. This is much better than sitting behind a wheel for 1hr+ a day doing nothing.
  - melling 12y ago
    People drive usually because it's either faster and/or cheaper. Right? I'd rather not intentionally make it expensive to drive so solve for X... Faster and cheaper... Everyone wants to save money and get home sooner.
    - pdonis 12y ago
      People drive usually because it's either faster and/or cheaper. Right? Or because it gives more freedom--you're not restricted to particular routes or particular times. Mass transit can beat driving on all these metrics (speed, price, and freedom of travel) when the population density is high enough that it's cost-effective for mass transit to have dense coverage, so that you're never more than a short walk from a train station or a bus stop. But many people (including me) don't want to live in a place with that high a population density. That's ultimately why mass transit hasn't caught on in the US the way it has in other countries.
      - melling 12y ago
        I thought that it went without saying that we were discussing mass transit in densely populated areas. If you don't live in such a place, you probably don't have 9 lanes of road either. As for why it hasn't caught on, it's because it's incomplete and inconvenient for most people. Even where it works, it's still not great. Ever take a slow bus across town in Manhattan? It's faster to walk.
        pdonis 12y ago
        I thought that it went without saying that we were discussing mass transit in densely populated areas. If you don't live in such a place, you probably don't have 9 lanes of road either. The 9-lane roads in metropolitan areas aren't confined to the densely populated areas; in fact, many of them are there only because so many people commute from the less densely populated suburbs to the densely populated inner city to work, instead of living in the inner city where they could easily take mass transit.
      - ido 12y ago
xvedejas 12y ago
A phenomenon very similar to "induced demand" was observed in 1865, when increased efficiency in coal consumption lead to increased demand for coal. It's called Jevon's paradox: http://en.wikipedia.org/wiki/Jevon%27s_paradox http://en.wikipedia.org/wiki/Jevon%27s_paradox
mcone 12y ago
It’s the roads themselves that cause traffic. The concept is called induced demand, which is economist-speak for when increasing the supply of something (like roads) makes people want that thing even more. So contrary to popular belief, invention is actually the mother of necessity. The question now is how best to take a systems approach to promoting alternative forms of transportation.
- scarecrowbob 12y ago
  "The question now is how best to take a systems approach to promoting alternative forms of transportation." If the principle, holds, obviously: build more.
  - 33W 12y ago
    I think that it might hold, at least for me. The biggest obstacles to my use of public transportation is the first mile and last mile, and the regularity of trips. Using Google Maps as my source, a trip home will take between 1hr, 3min to 1hr, 30min, and still includes driving for the last mile. Granted, this is San Antonio, which is certainly a driving city. The same drive home is 14-17 minutes, depending on route. In my calculus, drive vs. public trans. is a balance of which sucks least. Right now, I would say that the cost and altruism aspect of public trans. would allow it 200% of the suckiness allotted to driving. All else being equal, I would need a public trans. trip of ~30minutes or less.
gtCameron 12y ago
Weird title, seeing as how the article states that bigger roads do not make traffic worse, it stays the same: >> New roads will create new drivers, resulting in the intensity of traffic staying the same
- jusben1369 12y ago
  Good point. And it's still not completely clear that the roads are keeping up with the growth vs pulling it in. There were a couple of good points around larger interstate type services picking your town for HQ if you have extra capacity but in general it still seems too abstract.
- fulafel 12y ago
  Car traffic is harmful, so having more of it is bad.
tptacek 12y ago
There was more or less a whole EconTalk episode about this recently; one interesting point from it was the (bad) concept of STROADs: http://www.strongtowns.org/journal/2013/3/4/the-stroad.html#.U7GEXI1dUWs http://www.strongtowns.org/journal/2013/3/4/the-stroad.html#...
- maxerickson 12y ago
  The Stroad to street transition seems difficult to manage. The main street in my hometown underwent some of the transition, going from 2 lanes of parallel parking and 4 traffic lanes to diagonal parking with 2 traffic lanes and a turn lane, but the wide patch of asphalt is still there, and business isn't really thriving. I guess the general economic malaise there makes it hard to score development concepts on their own merits. It's interesting to look for the accidental victims of development, stuff like houses backed up against a road that probably started as a street. In areas where there is lots of room, the sensible thing is probably to just tear them down (or relocate them if that made sense), but people are too busy looking at the immediate impacts and ignore the needlessly low quality housing that will exist for decades (your link points out that the housing also makes the road less effective, which I hadn't considered).
- jessaustin 12y ago
  Thanks for this; it's a valuable concept I couldn't have articulated before. It seems I see stroads everywhere, and they do suck for pedestrians, cyclists, shoppers, businesses, and humans, but there isn't an obvious way to get from here to the improved future. At a certain population density, land simply is less valuable, no matter the road organization. I can imagine a town trying (and enforcing!) the street concept in a couple-block area, but how effective can that area be when everyone drives to get there? I almost suspect we'd need regular bus service, but at low population densities how does that work?
  - digikata 12y ago
    Use automated vehicles to supply an on-demand middle tier of transit. That layer could possibly provide transportation bridging low-density regions to a higher capacity fixed public transit nodes.
moron4hire 12y ago
I live inside the Washington D.C. beltway in Alexandria, VA. Traffic here in town is slightly better than what I had gotten used to in Philadelphia, but that's likely because A) I never have that far to go and B) I never drive during rush hour anymore. In the District, it's a fucking Boschian nightmare. DC typically ranks 2nd or 3rd worst traffic in the country, duking it out with LA and Miami. And all around me, as I look out my windows, all I see are skycranes build condo projects. On my walk to my local coffee shop, I see a political campaign poster touting the candidate will work to block some proposed parking garage project that I never understood why old people hated. There is a new metro station going in less than half a mile from my place. Except it won't be done for another 5 years or something. And really, the other nearest station is only a mile away over flat road. I don't understand putting metro stations less than half a mile from each other. That just seems more likely to cause traffic than it is to alleviate it, as it increases the latency of trips. There aren't any major road projects going on. There are one or two projects to fix up a few ramps that were crumbling. There is something about an express lane all the way to the Dulles airport. But nothing about the 95 expressway seems to be addressed. Clearly, someone is planning to pack a LOT more people into this area, but has given no thought whatsoever where to put their cars, either while in use or not. So I've just accepted that this is reality now. There is absolutely no reason to complain about traffic, because nobody is doing anything meaningful about it. I try to work my life to not be involved with it at all. I do most of my shopping online. I am a freelancer who works 100% from home. I live in walking distance of a bar and a coffee shop, and I'm even cutting back how often I go. Unless I can finally convince my wife to move out of this place, I'm not traveling anywhere during daylight hours.
jusben1369 12y ago
I'm not sure I'm a buyer of the congestion demand pricing. There's a very real cost already involved in traffic. Time lost in the car, quality of life, stress. Anybody who lives in the Bay Area, LA, NY, DC understand that timing your entire life around traffic is the regional pastime. So the argument then has to be an incremental one. If we then layer a more direct money tax of some kind on top of all the crap that already exists then that will be the straw that breaks the camels back and gets enough people off the road. Hmm.
- CanSpice 12y ago
  That's a sunk cost though. When someone gets in their car to drive somewhere, they don't think "this trip is going to cost me $7.50" because they pay for their gas at a different time, they pay for their insurance at a different time, they pay for repairs at a different time, and vehicle depreciation is largely invisible. They don't equate time lost to money lost either. However, if you have a big visual reminder that the road you're driving on will cost you money as soon as you drive on it, then people will be less likely to either take that route or drive altogether.
  - jusben1369 12y ago
    I hear you but I'm going to respectfully push back. When you live in a congested area you really do plan much of your professional and personal life around traffic. When to start work. When to leave work. When to schedule a meeting. When and where you'll go this weekend/vacation/kids. So this will make it more painful but it's hard to know how much this will be the final tipping point.
- revscat 12y ago
  We're about to see a large-scale experiment of demand pricing in a major metropolitan area: Dallas, Texas is implementing this very thing as part of the LBJ Express project.[1] It is scheduled to be fully completed by the end of 2015, but portions of it are already open to traffic, with the demand pricing in place. It will be interesting to see what happens. For the record, I can see the construction from my office window. I've used the express lanes a couple of times now, and traffic has always been clear on it when I did so. Whether this is due to pricing or simply because it is so new I am not sure. Either way, there was no traffic jams for me (during afternoon rush hour, mind) on the occasions I used them. [1] http://www.lbjexpress.com/FAQs.asp http://www.lbjexpress.com/FAQs.asp
moron4hire 12y ago
I wish there were a starter packet for using the metro. I hate it when people say, "where do you want to go? Oh, that's simple, you just take the Orange line to Such-and-such station. Why couldn't you figure that out? It's so simple." No, that is not simple. That's an insider's language designed to call out the outsiders. I get there and there isn't just an orange line. The orange and green lines overlap. Don't get on the wrong train at the right terminal! Or maybe it's like the purple line, where you have to take the orange line to get to it, and everyone else already knows this, but they don't tell you that, they just say "take the purple line" and I'm left standing there freaking out that I can't see a purple dot on a sign in a poorly-lit cavern. If I drive somewhere, all I need to know is where it is and where I am and I can eventually get there within 50% of the normal time to get there. Let's take this road that points towards where I want to go. That didn't work? Okay, let's take the next road that points to where I want to go. Unless you're driving around the Pentagon, which I'm fairly certain has had its road systems designed into the shape of a PENTAGRAM, then that will get you to where you want to go in the majority of the US. And grand total is still faster than walking to the metro, waiting in line for the train to show up, and waiting for it to stop at every spot in between.
- zaphoyd 12y ago
  Google maps / transit routing smartphone apps do a pretty good job of this. I've not had trouble coming into a new city, asking Google maps to give me mass transit directions and just following them. Most cities have real time bus/train trackers now that help you plan when to leave so you don't have to wait long.
  - moron4hire 12y ago
    Yes, Google Maps is how I manage it.
- skaevola 12y ago
  >I wish there were a starter packet for using the metro. A map? What else does a starter packet need to contain?
kenrikm 12y ago
I would contest that many roads are not built or expanded until they are needed and due to that the demand fills out the road on completion. If you were to take a 3 lane road that is at 70% capacity and make it 6 lanes I very highly doubt you would get a 6 lane road at 70% capacity. They reference a % thought an entire city, on a more Macro level a single bigger road can indeed ease congestion, though It may cause other roads leading into it to become congested. The only way out of the trap AFAIK would be to build excess capacity thought the entire system.
- ChuckMcM 12y ago
  Exactly this. Basically the 'demand' for driving is already > than the 'capacity' for driving, so adding capacity doesn't decrease congestion, it stays at 100%. This was made explicitly clear in the crash of 2000 when it felt like roughly 25% of the work force seems to have moved out of the Bay Area, traffic congestion got a lot less. If the theory of 'induced demand' was accurate, then traffic congestion would not have changed, and that would have been something worth writing about.
  - darkxanthos 12y ago
    This exactly. This article didn't even try to objectively validate the report. It's also provably false in other areas like already not very busy roads in the high desert in SoCal. Add a new road to Apple Valley and I bet it gets used but very little there's just no demand. This report was highly biased since I'm sure no one built a road where people didn't need one and looked if demand were the same. Instead this is only about building roads where they were deemed to be critical enough to warrant a ton of spending and where the built out supply probably lags demand.
- maxsilver 12y ago
  > The only way out of the trap AFAIK would be to build excess capacity thought the entire system. I agree. This makes a lot more since. The authors are taking good data, but making a big leap on their assumption to the cause. Roads don't "create" traffic. New roads in most major cities are never built until the old ones are already 300-500% over capacity. If you wait until your 500% over capacity, and then double the lanes, your still way over capacity, so the old and new roads are still "congested". This traffic isn't "new" -- it was always there, you just couldn't see it, because a 200% over capacity road, and a 500% over capacity road, looks like the same gridlock from the sky.
nawitus 12y ago
>This means raising the price of driving on a road when demand is high. During rush hour, drivers would have to pay a fee to use the most congested roads. Drivers already pay for the cost in lost time. It's a 'natural' market. The main problem with this article is the idea that the goal in traffic policy is to reduce congenstion. No, it should be to maximize utility. Sure, if you reduce roads, add congenstion charges then people will find alternatives to cars. That doesn't imply that utility is increased. Public transportation is typically worse than using a private car. You can't decide when to leave, you pretty much need to plan your trips around public transportation. They don't take you directly from A to B etc. Public transportation becomes effective only when population density becomes high enough.
- seizethecheese 12y ago
  'Drivers already pay the cost in lost time.' Yes, but not all of the cost. If each additional car adds 10 seconds to commutes, each driver will only pay a pittance more for her decision to hit the road. Meanwhile they are imposing large costs of 10 seconds * each driver on the road. Look up the economics of externalities again and you'll see that an additional congestion charge is well founded in theory.
  - kvb 12y ago
    I'm curious why this is being downvoted. Isn't congestion a textbook externality?
    - Dylan16807 12y ago
      Assume 100 drivers each cause 10 seconds of slowdown. Assume every driver is equally at fault. Each driver is causing 1000 person-seconds of slowdown. Each driver is receiving 1000 person-seconds of slowdown. Seems fair to me, and each driver is paying their exact cost. It's wrong to look at the externalities drivers output and ignore the externalities drivers input.
      - kvb 12y ago
larrydag 12y ago
Dallas is building a congested demand pricing project for the I-635 corridor. They are calling it managed toll lanes. http://www.txdot.gov/business/partnerships/current-cda/635-lbj-cda.html http://www.txdot.gov/business/partnerships/current-cda/635-l...
- alistairSH 12y ago
  I-495 through the VA side of the DC suburbs uses High-Occupany Toll lanes - demand pricing on top of HOV lanes. If you have passengers, you can use them for free. If you're solo, you pay the toll. They use a switchable EZ Pass transponder to make it work without toll booths at each end. Colloquially, they're referred to as "Lexus Lanes". As far as a I can tell, they haven't done much to reduce congestion on the non-toll lanes. But, if you can afford $12/day (peak rate, round trip) for a 10 mile stretch of interstate, you get to avoid the dirty, unwashed masses who are stuck in the poor lanes. :)
  - koenigdavidmj 12y ago
    The concern when this got deployed in the Seattle area is that it would be poorer people who are most likely to use these. Example: somebody trying to get to the daycare by 6PM so they don't get charged by the minute for being late.
    - crazy1van 12y ago
      Why is this a concern? It sounds like a completely rational decision for someone of any income level to pay money for a faster trip to avoid an even great amount of money in fines...
  - fataliss 12y ago
    Well, there is the same concept in LA, the 405 got "pool" lanes, usable for free when you got 2+ people in the car. The issue with this kind of lane is that it's the farthest left, and if your trip on the 405 is only a couple miles you gonna struggle most of your time to reach this lane and then leave it and reach the right lane before your exit when the road is jammed!
gweinberg 12y ago
Dolts like the article author completely miss the point. Yes, the number of people on the road will increase as we add lanes, but that doesn't mean that adding more lanes is useless. More people are able to get where they want to go, that's a good thing.
- gerbal 12y ago
  Building alternative high-volume modes of transportation is more effective than building larger roads. Adding more lanes is useless from a urban planing point of view because it doesn't alleviate congestion.
ehosca 12y ago
Yes, I’ve been stuck in traffic on 405, but it’s not like you never get through.
gldalmaso 12y ago
>> If we gave drivers some extra incentive to avoid the most congested hours, we could better utilize the roads’ capacities. There is already enough incentive, the incentive is to avoid seeing your hours waste away on traffic. Most people don't really get to choose their hours, with or without incentive, otherwise they already avoid the most congested hours. So the suggested incentive doesn't really make a difference when it's not a matter of choice, except by taking money away from people without adding any value.
- taejo 12y ago
  So we need to incentivise the people who set the hours.
cs702 12y ago
In addition to the correlation found by these researchers, I suspect the Braess Paradox[1] and other complex network phenomena are also at work. -- [1] Adding more roads to a network of roads can make traffic worse (and viceversa, closing roads can make traffic better). See http://en.wikipedia.org/wiki/Braess's_paradox http://en.wikipedia.org/wiki/Braess's_paradox or watch this friendly explanation: http://www.youtube.com/watch?v=ZiauQXIKs3U http://www.youtube.com/watch?v=ZiauQXIKs3U -- Edits: moved links and parenthesis to footnote, and added "In addition to the correlation found by these researchers" and "other complex network phenomena" to make my point clearer.
- bigdubs 12y ago
  The video doesn't do a good job of explaining this at all. Ultimately the reason why adding more roads to a system produces more traffic is more people take cars vs. public transit.
  - vitoreiji 12y ago
    > Ultimately the reason why adding more roads to a system produces more traffic is more people take cars vs. public transit. More precisely, more people take cars vs. not take cars. "Not take cars" can be public transit, human powered transport or even not moving at all.
    - mturmon 12y ago
      This correction might seem pedantic, but I think it is important. One of the lessons of these "paradoxes" (more roads = more congestion) is that one must take into account the whole traffic system. I'd add that another salient factor is people's housing choices relative to jobs and other destinations -- there is an interplay between road-building and housing construction.
  - cs702 12y ago
    bigdubs: that video explains the Braess paradox, not the correlation found by the researchers. I modified my comment to make that clearer. Thanks!
adamgravitis 12y ago
Having done some grad work in this area, I'd say this is a fairly superficial take on the topic. This certainly describes one area on the supply/demand curve, and perhaps even a pervasive one given that we essentially stopped building highways 40 years ago, but it's not inherent to the problem. I think it's very possible to jump ahead of this effect, but the capital outlay would be impressive, and as a society we apparently aren't permitted to accomplish Big Things anymore, so it's likely we stay in this weird bit of the function for a long while.
- xenadu02 12y ago
  Who stopped building highways? In the Dallas area we've been building and expanding them non-stop for decades now. My experience is people have simply moved further out, increasing traffic flowing into the newly expanded/built roads, and overall congestion has remained constant. But I think many of us would agree about accomplishing Big Things. Here's the dirty little secret: the US Government has almost always funded those "Big Things" and taxed the rich heavily to do it. The Interstate highway system was funded by a massive (as a percentage of the price per gallon) gas tax, along with a 90% post-war income tax rate on the rich. Even the trans-continental railroad was funded thanks to guarantees, loans, etc from the US Federal government (including sending the Army out shoot Native Americans and bandits who attacked the railroads). No private entity was willing to take such a large risk - it could have bankrupted even JP Morgan if it went bad. Without "Big Government" support the line never would have been built. I'm all for bringing back much higher taxes on the rich - tax anything over $1 million income at 50%, over $10 million at 60%. Same for cap gains. Use that money to fund massive expansions of roads, build subways under every major city, heck start a government-funded bank that gives anyone who wants to start a business a loan (it's what the Chinese government does). We could do a ton of "Big Things" if we were willing to tax the uber-rich to pay for it.
  - ams6110 12y ago
    Taxing the rich simply incents them to behaviors that avoid the tax. Government revenues increased dramatically when the high marginal tax rates were cut. Unfortunately government expenditures increased even more dramatically.
frogpelt 12y ago
I'm a huge fan of toll roads. And I really like charging for use at certain times. Perhaps you could reduce rates for each passenger in the vehicle. Maybe a four-passenger vehicle gets to drive free anytime. This encourages car pooling for those who can't afford to pay the tolls. In fact it may create new jobs.
DINKDINK 12y ago
Driverless cars have the vast vast potential to fix traffic congestion problems. Traffic mainly results from humans' inability to gauge the spacial and speed based tolerances required to prevent braking and as a result sending a backward brake wave through the cars behind it. Add to that fact that there are no game theory advantages to a single driver to driving properly (other than an altruistic realization that if you decide to drive with better tolerances and other people do the same, the congestion is abated)
- nulltype 12y ago
  That seems dubious. There are a finite number of cars you can get on the road at a given speed. If the total travel time is roughly a constant as this article implies, autonomous cars will be equivalent to adding a few more lanes, meaning there will be no long-term change.
  - DINKDINK 12y ago
    Traffic results when car densities pass a certain threshold and the speed the cars are traveling at prevents humans from being able to react in time or appropriately. You might have even seen this phenomenon in real life: Driving on a highway, suddenly you get stuck in traffic. As you pass through the traffic zone, there are no cars pulled over, no accident, no disruption in the quality of road. What most likely happened was that someone accidentally slammed on their brakes which caused an increase in car density. If there are enough cars that are in bound to this traffic zone before the density can disperse, the traffic zone will persist. Also notice that traffic zones often appear in situation where there's a positive increase in elevation. What happens is that if people aren't using cruise control (or their cruise control, control system isn't tight enough) their speed will decrease as they ascend the hill, causing some congestion and as like if the density of traffic is high enough, the cars behind them will have to slow down. You may think that if the cars behind them are also ascending the hill they'll also slow down in the same way but some cars may use cruise control while others don't (resulting in congestion) or the differences in each car's torque, power-output, efficiency curves differ causing each to slow down at different rates (often leading to the least capable car governing the rate) Use a worst-case scenario to analyze. Assume you have a network of diverless cars all linked together that maintain equidistant space between each other. If a new cars needs to join their network / pack the minimum amount of delay that the cars (behind the entering car) need to encounter is the (Length of the incoming car + gap tolerance between the other car) / (the sustained speed of the pack) =25/5280/65*3600 ~= .25 seconds per car. Now do a thought experiment that the high way you drive on was completely full (like we said in our original problem statement) do you think if you added one additional car to the highway, would everyone's (who's downstream of the merge) commute time be only increase ~.25 seconds? I'm very confident it's be much more than that. Traffic management is a task that needs high coordination, cooperation and reaction times above what unassisted humans are capable of.
deleted 12y ago
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skriticos2 12y ago
Well yes, people are irrational. I personally think that a lot of jobs today don't justify driving around at all. What difference does it make if you code in the crowded building of your employer or at home and use tele-conferences to talk with each other? Maybe you would even be more productive if you got rid of all the stress caused by commuting around a substantial portion of the day. I guess a good chunk of the office work done today could be replaced by remote work, but employers insist on everyone to get into the car, commute and thereby congest roads and burn up non-renewable petrol. I am seriously wondering why the working population don't bill the time and expenses of commuting to the employers? Most entrepreneurs do. You pay $50-$100 for the plumber to come to your place (just to come there, work is billed extra). Why not office workers?
phkahler 12y ago
These guys are partially idiots. Obviously there is more demand than road if use is directly proportional to supply as they claim. The problem is the way we design cities and lay out the roads. A regular grid where we put STOP lights? seriously? Go, stop, go, stop. And then we put businesses right on the corners to increase congestion right where it's already bad. When cars get tested for EPA MPG ratings, the average speed on the city drive cycle is slightly under 20mph due to all the stop and go. Hybrid cars get better city mpg than highway by using regenerative braking to recover energy from all that stopping and making drag the dominant factor. I don't think traffic circles are relevant, but designing the layout to minimize disruptions to flow altogether. I've been contemplating this a lot, but can't write it all here right now. Imagine if every drive were 10-20 percent longer distance, but you could average twice the speed over the journey! You'd save gas and time. And if your journey takes less time, that's fewer car-minutes on the road which means less traffic and they could have fewer lanes. The problem is even if we could do the design correctly, nobody is going to build a city from scratch - except in China maybe.
- avn2109 12y ago
  Building a city from scratch and designing it primarily with private automobile traffic in mind is a textbook case of Doing It Wrong. The only sane approach would be to build a subway (or maybe streetcars that have right-of-way) and then stick a city on top of it.
- andys627 12y ago
  It seems like you're assuming that the only priority is moving cars around - not walkability or livability. In other words it seems you're assuming the only purpose of the built environment is to move cars. I argue that it isn't and in that case we should measure other stuff besides moving cars efficiently when building our cities.
  - phkahler 12y ago
    No, I advocate efficiency as a goal weather it be cars, public transit, or something else. Personally I'd like easy access to both. But public transit is only viable with high density and I don't like the way we do dense either.
sologoub 12y ago
This article seems like a gross oversimplification. There are a lot more variables at play here than just what people tend to do with extra capacity. Terrain and flow dynamics, as well as driver behavior, have a lot to do with it. Take 405 in West Los Angeles for example. On one side it has the Sepulvida pass with very steep decent going south and ascent going north. It is crossed by I-10 going to Santa Monica and Downtown, a little further in 90 goes to Marina del Rey, and then exits for LAX. If you examine this section as an example, you have number of people either trying to get in or pass through this section during commuting hours. From the north, the sepulvida pass makes people slow down as they climb the hill. Not exactly sure why, but many drivers seem to be afraid of it. This recoils through the rest of the traffic, as each incremental car slowing down results in the car behind it slowing down slightly more. Once you get down the hill, you have people exiting and entering with very short distances to decelerate or accelerate, causing more slow downs. On the other side, you have a similar dynamic, but people are also trying to merge to or from 90 and I-10. With majority of the traffic heading either to Santa Monica, West LA, Century City or Hollywood/Downtown/something in between. The city has recently completed a major expansion on the 405 in that area adding a carpool lane, but more importantly changing how you merge to/from several of the exits, including Wilshire blvd and I-10. In my observation, the carpool lane did relatively little, but the smoothed exiting/entering with enough time to accelerate shifted the bottleneck from before Wilshire blvd, frequently spilling past the 90, to no ending around Wilshire. The flow restriction now seems to be the dreaded 101 interchange, with a huge amount of traffic stuck in the Sepulvida pass. As the result, I can not get from the 90 to I-10 in about 10 mins, whereas before it was easily 30. Point being, that if you maintain road size (or marginally improve it) and optimize the flow, you get a lot better returns.
- gr3yh47 12y ago
  apparently, correlation is equal to causation[1] [1]entire article
  - moskie 12y ago
    I don't think that applies. Isn't the point (or one of the main points) of building more roads to make traffic congestion better? The study in this article shows that that doesn't pan out.
lelf 12y ago
The actual paper http://www.ademloos.be/sites/default/files/meccano_docs/The_Fundamental_Law_of_Road_Congestion_Evidence_from_US_Cities.pdf http://www.ademloos.be/sites/default/files/meccano_docs/The_...
chsonnu 12y ago
Unused road space is staring everyone in the face and only a small percentage of commuters are using it: motorcyclists. If you just took 10% of the cars off the road and had them riding and lane splitting instead, congestion would be reduced exponentially. The good news for Californians is that lane splitting is actually legal unlike every other backwards ass state.
DigitalJack 12y ago
I have only read the linked article, not the study, but it seems to me to be a bizarre conclusion that if capacity is increased and utilization remains at maximum, that the capacity caused the utilization. It seems to be a much simpler scenario that demand far outstrips capacity, and until you can meet the demand, saturation every lane added will continue to be saturated. I'm sure amdahl's law applies to lane adding here, on top of the fact that all the highways I've seen merge from one side or the other. I don't think I've seen any that merge in the middle, though I guess they probably exist.
logfromblammo 12y ago
This is exactly the sort of thing that I don't want a politician to read. A study finds a correlation between construction of new roads and increase in driver miles. A policy-maker, never one for logic, transmutes correlation to causation. Now, it may be that they assume that increased demand for travel causes road construction, and assign resources to reduce the total cost for each trip. Good for them. But they may also assume that more roads cause more travel, and decide to prevent trips by destroying roads. Boo. You could as easily prevent water from flowing downstream by building a dam. Then your stream becomes a reservoir, the downstream flow rate reduces while it fills, then the reservoir spills over the dam at the same rate it flowed before. People want to move around. They want to travel freely between the places they can earn money, the places they can spend it, and the places they enjoy keeping their stuff. Making the travel more difficult makes them unhappy, while making it easier makes them more content. For the most part, the desire to move minus the cost of the trip results in economic activity. If that number is zero or negative, people stay put, and don't add to economic circulation. Human movement is an economic engine. You can add friction to it and generate more heat, or you can remove friction and extract work instead Generally speaking, you want people to take more trips, and you want the cost per trip to be as low as possible. That doesn't necessarily mean building more, wider, and longer roads. You may be able to get better results by siting the popular destinations more closely to each other, and ensuring that the routes between them are direct, non-viscous, and non-turbulent. When you do something stupid like make 3000 people work in one building complex, far away from homes or other businesses, and have everyone sleep in a suburban bedroom community, far away from jobs and shopping, yes, the road that is the best available route between them will be packed every single day. You cannot economically reduce traffic by narrowing that road. The cars you see on it will go down, but that is because people quit their jobs or moved their households over the arduous commute. They went somewhere else, and will be earning and spending there, instead. It would be better to simply put the homes, businesses, and offices closer together, and diffuse the obvious trips onto roads in such a way that they are neither over or underutilized.
- bcoates 12y ago
  > But they may also assume that more roads cause more travel, and decide to prevent trips by destroying roads. Politicians in the city I live in are literally doing this, installing "traffic calming measures" (destroying perfectly good road lanes that were just resurfaced) I believe phase two involves generating clean energy by harnessing the power of Bastiat spinning in his grave.
cyphunk 12y ago
Finally, businesses that rely on roads will swoop into cities with many of them, bringing trucking and shipments. Indeed, roads are most often built to bring in new large corporations that create jobs. Depending on how one measures "quality of life" this could be considered a very good thing. I was expecting something more interesting such as the correlation to car driver behaviour and inefficiency with stop-go traffic when not leaving a buffer in front of the next car (something that was written up very well a year or so ago) and how this logic is effected with wider roads. Instead, got some pretty worn out theories.
transfire 12y ago
What a bunch phooey. Just more peddling of flawed studies to promote increased taxation. If you want to reduce congestion try the obvious. 1) Mixed zoning, allowing more residential and retail to be close together. So people have less distance to travel. 2) Raise speed limits where possible so people can get to their destinations faster. 3) Build for the future. Don't just add a lane or two, add six. 4) And yes trains, do help. The problem in the States is that we hardly have any. Only the major metro areas have any sort of adequate rail system and even they are fairly slow, limited and antiquated. Which brings me to my last point: 5) Consult with Elon Musk.
- smutticus 12y ago
  Can you please explain how taxation plays into this? Are you implying that decreased investment in roads coupled with increased investment in public transit would increase taxation? What's your argument?
- xenadu02 12y ago
  I'm sorry but you are simply way off base. When a road is expanded, it does temporarily shorten commute times and reduce traffic. But that makes the cheap land farther away from everything more desirable, causing people to move out further, increasing traffic. Those new suburbs require a massive infrastructure investment to install water, sewer, gas, electricity, etc. Not to mention building surface streets, schools, libraries, shopping centers, etc. We've been building roads at a massive clip around the Dallas area, sprawling out over huge suburbs, many of which support mixed development (as does the city of Dallas itself). When I first moved here, the previous two lane highway had just been turned into a six lane toll road and there were no traffic jams, not even during rush hour. It's been 8 years and now we have stop and go traffic every day for about a 30 minute window and that window continues to grow larger. If you think about the design of roads it should become clear why this happens... You have many on-ramps dumping cars into a fixed set of lanes. If, at any point, there are more cars that want to enter than there is room traffic must slow to accommodate them. In reality it happens before the road is full as people leave space for braking, etc. When that happens at any point, it creates a wave of slowed traffic that begins to ripple backwards from that point, meaning anywhere further backward that is close to capacity begins to jam up, making it even more difficult for new vehicles to enter the roadway, amplifying the wave even more. Even if demand were 100% evenly spread out (which it never, never will be simply by the fact that brand new areas have empty fields or wooded lots - it takes time to build offices, start businesses, etc), the friction of merging & exiting the highway would eventually require more cars to exit than are entering, the exact opposite of rush hour conditions. Building more lanes merely delays the inevitable; that's assuming you can, which in Dallas is impossible - most of the current roads (and 100% of the worst congested ones) would require tearing down skyscrapers or 100% tunneling / elevated highways because there is no more space.
vermooten 12y ago
well duh
nardi 12y ago
So more lanes don't reduce congestion, but this article ignores the fact that they obviously DO increase quality of life, by giving people the freedom to live and work where they choose. We should build more lanes for that reason alone. The reason congestion doesn't get better is simply that there is pent-up demand for driving. The solution isn't "tough luck, adjust your life to fit the traffic." It's to build more lanes, so people can choose to live the life they want to live.
- stinos 12y ago
  they obviously DO increase quality of life If you only consider the aspect of freedom, maybe. But there are more aspects of quality life to consider imo. Spending hours in a car, practically standing still, causes stress. More lanes? More stressed people, higher volume of traffic jam - is that still freedom, sitting inside a metal cage while you can't go forward or backward? Increased number of cars driving means increased pollution. More lanes means less space for buildings and nature. Etc. I get your point, but I think there is more to it.
  - nardi 12y ago
    This argument boils down to: "People don't know what's best for themselves, so we shouldn't give them what they clearly want." I can sympathize with that somewhat, but I think that's a dangerous direction for a government to go in.
- Vik1ng 12y ago
  Short term maybe, but long term it is really just a waste of resources and certainly not a better life for the next generations. Promoting alternatives outside big cities and spending the money there to attract companies instead of spending it on roads would make much more sense.
- baddox 12y ago
  > they obviously DO increase quality of life Perhaps not, if you take into account the resource costs of road infrastructure (which are fairly hidden by government) and the health impact of automobile usage (from pollution, commuting hours, and obviously road accidents). The thing is, massive public subsidies for roads might be the reason that so many people need to travel far from their homes to their work. You're assuming that the causal relationship goes one way, but it could just as easily go the other way.
jrobbins 12y ago
I see it as basically Malthusian: people will keep driving until it is so unpleasant that they don't want to do it any more. The tipping point for most people is around 45 minutes. Here's a book with a footnote that mentions that the same 45-minute rule applies worldwide and though out history: http://books.google.com/books?id=uuqIA-ce1CoC&pg=PA408&lpg=PA408&dq=ancient+romans+commute+45+minutes&source=bl&ots=W_4--bDOo5&sig=uNYXKSxadR3pUeZ3epHuKgvI0GQ&hl=en&sa=X&ei=xLGxU-vIHoiTqgaUhIDYDQ&ved=0CDEQ6AEwAg#v=onepage&q=ancient%20romans%20commute%2045%20minutes&f=false http://books.google.com/books?id=uuqIA-ce1CoC&pg=PA408&lpg=P...
CamperBob2 12y ago
Then clearly we can make traffic flow more smoothly by shrinking existing roads. Right? What? No? It doesn't work that way? Hmm, what a coincidence, it appears we're already at the sweet spot on the traffic-flow Laffer curve. Either that, or what the authors of the study are trying to optimize is very different from what the typical driver is trying to optimize.
fataliss 12y ago
I wish, LA had a good public transportation network but it doesn't. I used to take the bus, I had to change twice and spend at least 1h traveling, while it takes me 12 to 20min using my car (20min on exceptionally busy days). It probably is one of biggest city that doesn't have an underground metro! I guess that's one of the rare thing I miss from NYC. Being able to move fast without owning a car!
baddox 12y ago
It's an interesting effect, and fairly obvious once you hear the explanation the first time. This article focuses primarily on the effect that roads have on their own congestion, but I think you can do similar analysis on the effects of roads on many other things. This sort of idea is discussed a lot in the libertarian community. I don't intend to make the conversation about that; I just want to mention the ideas because they're similar. Basically, a common and oft-parodied criticism of libertarianism is "but who will build the roads," implying that massive road infrastructure is something that can only be produced by government through taxation and eminent domain. One common retort by libertarians is to come up with a bunch of proposals for how private enterprise could create a very similar road system to what we have today. I think that's the wrong approach. I'm more interested in the ways that government roads, no matter how well-intended they are, can lead to inefficiency and perverse incentives. I think the biggest and easiest argument to make is an environmental one, which is somewhat ironic, considering that libertarians are generally considered (by themselves and others) as a threat to environmentalism. And yet, I wager that public road infrastructure is one of the most obvious cases where government programs lead to (probably unintended) environmental problems. The interstate highway system is a massive blow to railroads, which have a vastly smaller environmental impact than road freight. The public road funds essentially subsidize the price of fast shipping via truck. Big trucks are probably responsible for a disproportionately large portion of road wear relative to the funding of roads that they provide. Another interesting effect is that urban sprawl probably wouldn't happen without roads which are primarily produced by government. This is probably another big threat to the environment, since I would imagine that suburbs pollute much more per capita than urban areas because of the necessity to use automobiles.
- mjburgess 12y ago
  I think the "roads" problem is just a simple and easy example of the general class of collective action problems that require a single authority to manage. Here is another example: the design of a network cannot be modified arbitrarily. It's rational for a private company to insert a road into a system to benefit itself at the disadvantage to others (cf. negative externalities). Indeed it's rational for several to do this making ad-hoc modifications to the network, the net result of this is significant inefficiency. Collective action problems and (negative) externalities are the main cases where we require a single-point-of-trust / authority to coordinate a system. Libertarians say that private companies can do this, but when you ask "well what do these companies look like?" you invariably get something like a small government. The moral question then arises: we have these single-points-of-trust, do we have any democratic control over them? The answer, in a libterian system is No (money != vote). The libertarian solution to these problems then, seems to me, to hand them over to private tyrannies with no public accountability to perform largely the same function as a government. Its at this point the "NOPE!! LEAVE ME ALONE!" tends to come out.
dasil003 12y ago
I witnessed a nice microcosm of this demonstrating how fast the shift occurs. Every day I cycle commute up the London A24/A3 (CS7) corridor. On the first day of the first tube strikes early this year, the congestion was insane. I mean the worst traffic I've ever seen in my life. An ambulance was literally stuck in traffic and no one within earshot of the ambulance able to move their vehicle enough for it to get through. But then the second day of the strike traffic was a bit on the heavy side but mostly back to normal. I think a huge number of people realized that it was actually pointless to even attempt to go to work unless they were walking or biking. This effect even carried over to the second tube strike a month or two later.
tunesmith 12y ago
It's interesting that they make the point that congestion pricing will induce people to take alternate routes. The recent update to Google Maps seems to do the same thing. It's much more proactive now about suggesting alternate routes. Here in Seattle, I recently bypassed I-5 by taking an astonishingly complex and twisty route that was all prompted by Google Maps, and I got to my destination five minutes sooner than Google was estimating I would had I stayed on I-5 (although that's impossible to verify since traffic congestion changes throughout the duration of a drive). All that said, while it was fun (also especially when I avoided a Tacoma I-5 snarl that I hadn't previously known how to avoid), I don't think we actually want to redirect highway drivers onto local streets. Local streets aren't designed for highway overflow; they're designed for local traffic. Isn't the real answer to design more decentralized town areas so people have less reason to drive long distances, for reasons other than recreation?
- joeguilmette 12y ago
  sounds like a great solution to the problem if you have the luxury of solving it before it is a problem. i don't think that demolishing and rebuilding the metropolitan Seattle area is a viable solution to the traffic issues that area faces.
- judk 12y ago
  Try the math. For a given number of people, centralizing reduces everyone's commutes. The key is to not separate housing from commerce and business.
anoxic 12y ago
This actually makes sense in an unintuitive way.
legohead 12y ago
I've always thought something is definitely wrong with the way we think about roads when car pool lanes end up just as busy/gridlocked as the rest of the road.
zmmmmm 12y ago
Yet when I visit a small country town with a giant road through the middle, there is still no traffic there. If big roads induce traffic independent of any other factors then this should not be true - the mere presence of the big road should have created traffic. While I understand there's a really point to this paradox (it really happens), I hate the simplistic conclusion people reach that it is always wrong to make a road bigger. Sometimes you really do need a bigger road. Sometimes you really need more public transport or something else. It's complicated, and we need better models of it. But reducing it to one line slogans doesn't help that.
- nickonline 12y ago
  That's kind of the point made about halfway through the article where he states if you expand a road to 100 lanes you won't ever see any traffic. In those country towns with a population of 30,000 but a super road through the center that could carry 100,000 people a day the road _is_ the same as if that 100 lane highway had been built in a major city. In the article they state that there are more factors at work but they do need a title for the article that will draw people to read it.
  - astrodust 12y ago
    I think highways like the 401 in Toronto prove that the "100 lane" theory is pretty much bullshit. https://en.wikipedia.org/wiki/Ontario_Highway_401 https://en.wikipedia.org/wiki/Ontario_Highway_401 It's arguably the busiest highway in North America based on a number of metrics, even more volume than LA's perpetually busy Santa Monica Freeway. They've been expanding it ever since they've built it and in parts it is 25 lanes wide. It's slammed all the time. Traffic jams at 3am aren't unheard of if they're doing road work and it's slimmed down to half capacity. It was once merely an 8 lane highway, so the idea that tripling or quadrupling the size of a highway magically makes traffic jams go away is so far from the truth. There's a parallel highway running north of it that's paid by tolls which isn't as busy, but only because they can adjust pricing according to demand.
bane 12y ago
I feel like there's a cause and effect relationship being presented here that isn't necessarily true, even if the correlation is true.
uint32 12y ago
Also: bigger/faster computers makes programs bloated/slower.
aaron695 12y ago
This article is rubbish > What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse > For instance, Paris in recent decades has had a persistent policy to dramatically downsize and reduce roadways. “Driving in Paris was bad before,” said Duranton. “It’s just as bad, but it’s not much worse.” Bigger roads are worse, and smaller roads are worse? There's a point here somewhere but they've failed to make it.
- emj 12y ago
  I guess they get more foot traffic, and living streets (more shopping/social life etc). If you get that and less cars in traffic I guess I see a win there.
drawkbox 12y ago
Sounds a bit like Parkinson's Law: http://en.wikipedia.org/wiki/Parkinson's_law http://en.wikipedia.org/wiki/Parkinson's_law "The demand upon a resource tends to expand to match the supply of the resource."
brianstorms 12y ago
This is nothing new. Read Robert Caro's 1974 Pulitzer Prize-winning book THE POWER BROKER if you wanna know about roads and highways and freeways and how expanding them only makes traffic worse.
_Adam 12y ago
The article fails to follow the logical process to the very end. What isn't being asked is: why are humans using that road when they weren't using the smaller road before? Humans don't just drive for the sake of doing so. They drive because they have the need to do so. Building roads lowers the perceived time cost of driving, so more people drive, and more people drive at the time that is most desirable to do so. In some cases this results in increased congestion, but if the need of the population is met or exceeded, then the result is smooth traffic flow. Even if the bigger road is more congested, it may still have a greater net traffic flow, and that increased flow results in greater economic and societal good. For example, because of new highway XYZ, I can now work somewhere that was formerly too far a commute. The problem isn't solved by building smaller roads, it's solved by building even bigger roads, or building roads in a more optimal fashion (selecting a route for a new road that matches the transportation needs of the population).
Corrado 12y ago
What about a smartphone app that helped you avoid the most congested roads. I think Waze does something like this today and I'm sure that Google Maps can as well. We just need to have it integrated into the system so that we don't have to think about it. I think this is where projects like Andriod Auto & iOS CarPlay come into play. Just jump into your car and say "Take me to Julia's house" and the route will be mapped out for you. I would love to not have to figure out the best way to get to the mall on a busy Saturday afternoon! Even better, an auto-driving car will actually take care of the moving bits as well as planning your route.
peter_l_downs 12y ago
Funny to see this on the HN frontpage – the Downs who originally suggested the "fundamental law of highway congestion" being confirmed in the paper [0] is my grandfather. Thanks for submitting this, it's very interesting work. [0] http://www.nber.org/papers/w15376.pdf http://www.nber.org/papers/w15376.pdf
duncan_bayne 12y ago
Counterargument here: http://pc.blogspot.com.au/2014/06/more-roads-doesnt-mean-more-traffic-jams.html http://pc.blogspot.com.au/2014/06/more-roads-doesnt-mean-mor... "By comparison, building expensive transit systems aimed at getting people out of their less-expensive cars generates zero economic benefits if it generates no new travel. Only new travel generates economic benefits, so people who argue that new roads induce new travel are actually arguing that new roads create economic benefits. If congestion is the issue, then–as Mann briefly mentions–the solution is congestion pricing. But Mann doesn’t understand the difference between true congestion pricing and New York City’s proposal for cordon pricing. Cordon pricing is more a way of raising revenue to fund urban boondoggles than a way of relieving congestion. Even UC Berkeley planning professor Robert Cervero believes that the induced demand argument is “wrong headed.” “Road investments by themselves do not increase volumes,” he writes. “Only by conferring a benefit, like faster speeds, will traffic increase.” Provided that benefit is greater than the cost–something that could be assured, Cervero says, through proper pricing of roads–then it is a good thing."
StillBored 12y ago
I think studies which measure traffic congestion in the US based on road building over the last couple decades IMHO are flawed. That is because I believe how and where you build the road is more important than how much road you build. For example, where I live the main roads in the city proper haven't been upgraded in the last 40 years. Yet, new roads funneling drivers from farther and farther out are being constructed all the time. This simply means that the first 1/2 of many drivers commutes involves sailing along a new road until they hit the old roads, and then puttering around at 5mph (or worse) for the last 5-10 miles of the journey.

212 points by data_scientist 12y ago

They're also an eyesore. Not to worry, over the next several decades large cities will build out effective mass transit systems. High-speed rail will eventually come to America after years of debate. Look to China to lead the way. What's this low-speed maglev that they're building now? http://usa.chinadaily.com.cn/epaper/2014-02/19/content_17291903.htm http://usa.chinadaily.com.cn/epaper/2014-02/19/content_17291...

pdonis 12y ago
over the next several decades large cities will build out effective mass transit systems Which, as the article points out, won't fix the traffic congestion, because as some people switch from driving to mass transit, other people will take their place by driving when they previously walked or just didn't make the trip at all. So mass transit can increase the total number of trips made, but it won't decrease road usage.
- personZ 12y ago
  http://www.theonion.com/articles/report-98-percent-of-us-commuters-favor-public-tra,1434/ http://www.theonion.com/articles/report-98-percent-of-us-com... It is the onion, and is flippant, but as a general belief it touches upon a basic truth -- everyone would love if everyone else used public transit, leaving the roads available for our use.
  - _delirium 12y ago
    This is occasionally used as an argument in favor of cheaper or free public transit: that even from a self-interest perspective, it makes sense for road users to subsidize public transit, as a way of effectively paying other people to get off the roads and out of their way. However most road users don't seem to see it that way.
  - TheCoelacanth 12y ago
    As with most articles from the Onion, there is an element of truth, but if you look at a city with good public transit options (NYC is the only one in the US) over 50% of commuters travel by public transit. If you look at cities with adequate but not great public transit options (DC, Boston or San Francisco) more than 30% of commuters travel by public transit.
- tormeh 12y ago
  People like me, who use mass transit, don't care about traffic congestion. Queue all you want. I just want more mass transit because travel by mass transit happens in constant time regardless of the amount of travelers (within reasonable bounds. Carriages do get full eventually).
  - martinald 12y ago
    The other benefit is being able to do something useful on the commute too. I can usually get through all my morning's emails on the train into work. This is much better than sitting behind a wheel for 1hr+ a day doing nothing.
- melling 12y ago
  People drive usually because it's either faster and/or cheaper. Right? I'd rather not intentionally make it expensive to drive so solve for X... Faster and cheaper... Everyone wants to save money and get home sooner.
  - pdonis 12y ago
    People drive usually because it's either faster and/or cheaper. Right? Or because it gives more freedom--you're not restricted to particular routes or particular times. Mass transit can beat driving on all these metrics (speed, price, and freedom of travel) when the population density is high enough that it's cost-effective for mass transit to have dense coverage, so that you're never more than a short walk from a train station or a bus stop. But many people (including me) don't want to live in a place with that high a population density. That's ultimately why mass transit hasn't caught on in the US the way it has in other countries.
    - melling 12y ago
      I thought that it went without saying that we were discussing mass transit in densely populated areas. If you don't live in such a place, you probably don't have 9 lanes of road either. As for why it hasn't caught on, it's because it's incomplete and inconvenient for most people. Even where it works, it's still not great. Ever take a slow bus across town in Manhattan? It's faster to walk.
      - pdonis 12y ago
        I thought that it went without saying that we were discussing mass transit in densely populated areas. If you don't live in such a place, you probably don't have 9 lanes of road either. The 9-lane roads in metropolitan areas aren't confined to the densely populated areas; in fact, many of them are there only because so many people commute from the less densely populated suburbs to the densely populated inner city to work, instead of living in the inner city where they could easily take mass transit.
    - ido 12y ago

xvedejas 12y ago

A phenomenon very similar to "induced demand" was observed in 1865, when increased efficiency in coal consumption lead to increased demand for coal. It's called Jevon's paradox: http://en.wikipedia.org/wiki/Jevon%27s_paradox http://en.wikipedia.org/wiki/Jevon%27s_paradox

mcone 12y ago

It’s the roads themselves that cause traffic. The concept is called induced demand, which is economist-speak for when increasing the supply of something (like roads) makes people want that thing even more. So contrary to popular belief, invention is actually the mother of necessity. The question now is how best to take a systems approach to promoting alternative forms of transportation.

scarecrowbob 12y ago
"The question now is how best to take a systems approach to promoting alternative forms of transportation." If the principle, holds, obviously: build more.
- 33W 12y ago
  I think that it might hold, at least for me. The biggest obstacles to my use of public transportation is the first mile and last mile, and the regularity of trips. Using Google Maps as my source, a trip home will take between 1hr, 3min to 1hr, 30min, and still includes driving for the last mile. Granted, this is San Antonio, which is certainly a driving city. The same drive home is 14-17 minutes, depending on route. In my calculus, drive vs. public trans. is a balance of which sucks least. Right now, I would say that the cost and altruism aspect of public trans. would allow it 200% of the suckiness allotted to driving. All else being equal, I would need a public trans. trip of ~30minutes or less.

gtCameron 12y ago

Weird title, seeing as how the article states that bigger roads do not make traffic worse, it stays the same: >> New roads will create new drivers, resulting in the intensity of traffic staying the same

jusben1369 12y ago
Good point. And it's still not completely clear that the roads are keeping up with the growth vs pulling it in. There were a couple of good points around larger interstate type services picking your town for HQ if you have extra capacity but in general it still seems too abstract.
fulafel 12y ago
Car traffic is harmful, so having more of it is bad.

tptacek 12y ago

There was more or less a whole EconTalk episode about this recently; one interesting point from it was the (bad) concept of STROADs: http://www.strongtowns.org/journal/2013/3/4/the-stroad.html#.U7GEXI1dUWs http://www.strongtowns.org/journal/2013/3/4/the-stroad.html#...

maxerickson 12y ago
The Stroad to street transition seems difficult to manage. The main street in my hometown underwent some of the transition, going from 2 lanes of parallel parking and 4 traffic lanes to diagonal parking with 2 traffic lanes and a turn lane, but the wide patch of asphalt is still there, and business isn't really thriving. I guess the general economic malaise there makes it hard to score development concepts on their own merits. It's interesting to look for the accidental victims of development, stuff like houses backed up against a road that probably started as a street. In areas where there is lots of room, the sensible thing is probably to just tear them down (or relocate them if that made sense), but people are too busy looking at the immediate impacts and ignore the needlessly low quality housing that will exist for decades (your link points out that the housing also makes the road less effective, which I hadn't considered).
jessaustin 12y ago
Thanks for this; it's a valuable concept I couldn't have articulated before. It seems I see stroads everywhere, and they do suck for pedestrians, cyclists, shoppers, businesses, and humans, but there isn't an obvious way to get from here to the improved future. At a certain population density, land simply is less valuable, no matter the road organization. I can imagine a town trying (and enforcing!) the street concept in a couple-block area, but how effective can that area be when everyone drives to get there? I almost suspect we'd need regular bus service, but at low population densities how does that work?
- digikata 12y ago
  Use automated vehicles to supply an on-demand middle tier of transit. That layer could possibly provide transportation bridging low-density regions to a higher capacity fixed public transit nodes.

moron4hire 12y ago

I live inside the Washington D.C. beltway in Alexandria, VA. Traffic here in town is slightly better than what I had gotten used to in Philadelphia, but that's likely because A) I never have that far to go and B) I never drive during rush hour anymore. In the District, it's a fucking Boschian nightmare. DC typically ranks 2nd or 3rd worst traffic in the country, duking it out with LA and Miami. And all around me, as I look out my windows, all I see are skycranes build condo projects. On my walk to my local coffee shop, I see a political campaign poster touting the candidate will work to block some proposed parking garage project that I never understood why old people hated. There is a new metro station going in less than half a mile from my place. Except it won't be done for another 5 years or something. And really, the other nearest station is only a mile away over flat road. I don't understand putting metro stations less than half a mile from each other. That just seems more likely to cause traffic than it is to alleviate it, as it increases the latency of trips. There aren't any major road projects going on. There are one or two projects to fix up a few ramps that were crumbling. There is something about an express lane all the way to the Dulles airport. But nothing about the 95 expressway seems to be addressed. Clearly, someone is planning to pack a LOT more people into this area, but has given no thought whatsoever where to put their cars, either while in use or not. So I've just accepted that this is reality now. There is absolutely no reason to complain about traffic, because nobody is doing anything meaningful about it. I try to work my life to not be involved with it at all. I do most of my shopping online. I am a freelancer who works 100% from home. I live in walking distance of a bar and a coffee shop, and I'm even cutting back how often I go. Unless I can finally convince my wife to move out of this place, I'm not traveling anywhere during daylight hours.

jusben1369 12y ago

I'm not sure I'm a buyer of the congestion demand pricing. There's a very real cost already involved in traffic. Time lost in the car, quality of life, stress. Anybody who lives in the Bay Area, LA, NY, DC understand that timing your entire life around traffic is the regional pastime. So the argument then has to be an incremental one. If we then layer a more direct money tax of some kind on top of all the crap that already exists then that will be the straw that breaks the camels back and gets enough people off the road. Hmm.

CanSpice 12y ago
That's a sunk cost though. When someone gets in their car to drive somewhere, they don't think "this trip is going to cost me $7.50" because they pay for their gas at a different time, they pay for their insurance at a different time, they pay for repairs at a different time, and vehicle depreciation is largely invisible. They don't equate time lost to money lost either. However, if you have a big visual reminder that the road you're driving on will cost you money as soon as you drive on it, then people will be less likely to either take that route or drive altogether.
- jusben1369 12y ago
  I hear you but I'm going to respectfully push back. When you live in a congested area you really do plan much of your professional and personal life around traffic. When to start work. When to leave work. When to schedule a meeting. When and where you'll go this weekend/vacation/kids. So this will make it more painful but it's hard to know how much this will be the final tipping point.
revscat 12y ago
We're about to see a large-scale experiment of demand pricing in a major metropolitan area: Dallas, Texas is implementing this very thing as part of the LBJ Express project.[1] It is scheduled to be fully completed by the end of 2015, but portions of it are already open to traffic, with the demand pricing in place. It will be interesting to see what happens. For the record, I can see the construction from my office window. I've used the express lanes a couple of times now, and traffic has always been clear on it when I did so. Whether this is due to pricing or simply because it is so new I am not sure. Either way, there was no traffic jams for me (during afternoon rush hour, mind) on the occasions I used them. [1] http://www.lbjexpress.com/FAQs.asp http://www.lbjexpress.com/FAQs.asp

moron4hire 12y ago

I wish there were a starter packet for using the metro. I hate it when people say, "where do you want to go? Oh, that's simple, you just take the Orange line to Such-and-such station. Why couldn't you figure that out? It's so simple." No, that is not simple. That's an insider's language designed to call out the outsiders. I get there and there isn't just an orange line. The orange and green lines overlap. Don't get on the wrong train at the right terminal! Or maybe it's like the purple line, where you have to take the orange line to get to it, and everyone else already knows this, but they don't tell you that, they just say "take the purple line" and I'm left standing there freaking out that I can't see a purple dot on a sign in a poorly-lit cavern. If I drive somewhere, all I need to know is where it is and where I am and I can eventually get there within 50% of the normal time to get there. Let's take this road that points towards where I want to go. That didn't work? Okay, let's take the next road that points to where I want to go. Unless you're driving around the Pentagon, which I'm fairly certain has had its road systems designed into the shape of a PENTAGRAM, then that will get you to where you want to go in the majority of the US. And grand total is still faster than walking to the metro, waiting in line for the train to show up, and waiting for it to stop at every spot in between.

zaphoyd 12y ago
Google maps / transit routing smartphone apps do a pretty good job of this. I've not had trouble coming into a new city, asking Google maps to give me mass transit directions and just following them. Most cities have real time bus/train trackers now that help you plan when to leave so you don't have to wait long.
- moron4hire 12y ago
  Yes, Google Maps is how I manage it.
skaevola 12y ago
>I wish there were a starter packet for using the metro. A map? What else does a starter packet need to contain?

kenrikm 12y ago

I would contest that many roads are not built or expanded until they are needed and due to that the demand fills out the road on completion. If you were to take a 3 lane road that is at 70% capacity and make it 6 lanes I very highly doubt you would get a 6 lane road at 70% capacity. They reference a % thought an entire city, on a more Macro level a single bigger road can indeed ease congestion, though It may cause other roads leading into it to become congested. The only way out of the trap AFAIK would be to build excess capacity thought the entire system.

ChuckMcM 12y ago
Exactly this. Basically the 'demand' for driving is already > than the 'capacity' for driving, so adding capacity doesn't decrease congestion, it stays at 100%. This was made explicitly clear in the crash of 2000 when it felt like roughly 25% of the work force seems to have moved out of the Bay Area, traffic congestion got a lot less. If the theory of 'induced demand' was accurate, then traffic congestion would not have changed, and that would have been something worth writing about.
- darkxanthos 12y ago
  This exactly. This article didn't even try to objectively validate the report. It's also provably false in other areas like already not very busy roads in the high desert in SoCal. Add a new road to Apple Valley and I bet it gets used but very little there's just no demand. This report was highly biased since I'm sure no one built a road where people didn't need one and looked if demand were the same. Instead this is only about building roads where they were deemed to be critical enough to warrant a ton of spending and where the built out supply probably lags demand.
maxsilver 12y ago
> The only way out of the trap AFAIK would be to build excess capacity thought the entire system. I agree. This makes a lot more since. The authors are taking good data, but making a big leap on their assumption to the cause. Roads don't "create" traffic. New roads in most major cities are never built until the old ones are already 300-500% over capacity. If you wait until your 500% over capacity, and then double the lanes, your still way over capacity, so the old and new roads are still "congested". This traffic isn't "new" -- it was always there, you just couldn't see it, because a 200% over capacity road, and a 500% over capacity road, looks like the same gridlock from the sky.

nawitus 12y ago

>This means raising the price of driving on a road when demand is high. During rush hour, drivers would have to pay a fee to use the most congested roads. Drivers already pay for the cost in lost time. It's a 'natural' market. The main problem with this article is the idea that the goal in traffic policy is to reduce congenstion. No, it should be to maximize utility. Sure, if you reduce roads, add congenstion charges then people will find alternatives to cars. That doesn't imply that utility is increased. Public transportation is typically worse than using a private car. You can't decide when to leave, you pretty much need to plan your trips around public transportation. They don't take you directly from A to B etc. Public transportation becomes effective only when population density becomes high enough.

seizethecheese 12y ago
'Drivers already pay the cost in lost time.' Yes, but not all of the cost. If each additional car adds 10 seconds to commutes, each driver will only pay a pittance more for her decision to hit the road. Meanwhile they are imposing large costs of 10 seconds * each driver on the road. Look up the economics of externalities again and you'll see that an additional congestion charge is well founded in theory.
- kvb 12y ago
  I'm curious why this is being downvoted. Isn't congestion a textbook externality?
  - Dylan16807 12y ago
    Assume 100 drivers each cause 10 seconds of slowdown. Assume every driver is equally at fault. Each driver is causing 1000 person-seconds of slowdown. Each driver is receiving 1000 person-seconds of slowdown. Seems fair to me, and each driver is paying their exact cost. It's wrong to look at the externalities drivers output and ignore the externalities drivers input.
    - kvb 12y ago

larrydag 12y ago

Dallas is building a congested demand pricing project for the I-635 corridor. They are calling it managed toll lanes. http://www.txdot.gov/business/partnerships/current-cda/635-lbj-cda.html http://www.txdot.gov/business/partnerships/current-cda/635-l...

alistairSH 12y ago
I-495 through the VA side of the DC suburbs uses High-Occupany Toll lanes - demand pricing on top of HOV lanes. If you have passengers, you can use them for free. If you're solo, you pay the toll. They use a switchable EZ Pass transponder to make it work without toll booths at each end. Colloquially, they're referred to as "Lexus Lanes". As far as a I can tell, they haven't done much to reduce congestion on the non-toll lanes. But, if you can afford $12/day (peak rate, round trip) for a 10 mile stretch of interstate, you get to avoid the dirty, unwashed masses who are stuck in the poor lanes. :)
- koenigdavidmj 12y ago
  The concern when this got deployed in the Seattle area is that it would be poorer people who are most likely to use these. Example: somebody trying to get to the daycare by 6PM so they don't get charged by the minute for being late.
  - crazy1van 12y ago
    Why is this a concern? It sounds like a completely rational decision for someone of any income level to pay money for a faster trip to avoid an even great amount of money in fines...
- fataliss 12y ago
  Well, there is the same concept in LA, the 405 got "pool" lanes, usable for free when you got 2+ people in the car. The issue with this kind of lane is that it's the farthest left, and if your trip on the 405 is only a couple miles you gonna struggle most of your time to reach this lane and then leave it and reach the right lane before your exit when the road is jammed!

gweinberg 12y ago

Dolts like the article author completely miss the point. Yes, the number of people on the road will increase as we add lanes, but that doesn't mean that adding more lanes is useless. More people are able to get where they want to go, that's a good thing.

gerbal 12y ago
Building alternative high-volume modes of transportation is more effective than building larger roads. Adding more lanes is useless from a urban planing point of view because it doesn't alleviate congestion.

ehosca 12y ago

Yes, I’ve been stuck in traffic on 405, but it’s not like you never get through.

gldalmaso 12y ago

>> If we gave drivers some extra incentive to avoid the most congested hours, we could better utilize the roads’ capacities. There is already enough incentive, the incentive is to avoid seeing your hours waste away on traffic. Most people don't really get to choose their hours, with or without incentive, otherwise they already avoid the most congested hours. So the suggested incentive doesn't really make a difference when it's not a matter of choice, except by taking money away from people without adding any value.

taejo 12y ago
So we need to incentivise the people who set the hours.

cs702 12y ago

In addition to the correlation found by these researchers, I suspect the Braess Paradox[1] and other complex network phenomena are also at work. -- [1] Adding more roads to a network of roads can make traffic worse (and viceversa, closing roads can make traffic better). See http://en.wikipedia.org/wiki/Braess's_paradox http://en.wikipedia.org/wiki/Braess's_paradox or watch this friendly explanation: http://www.youtube.com/watch?v=ZiauQXIKs3U http://www.youtube.com/watch?v=ZiauQXIKs3U -- Edits: moved links and parenthesis to footnote, and added "In addition to the correlation found by these researchers" and "other complex network phenomena" to make my point clearer.

bigdubs 12y ago
The video doesn't do a good job of explaining this at all. Ultimately the reason why adding more roads to a system produces more traffic is more people take cars vs. public transit.
- vitoreiji 12y ago
  > Ultimately the reason why adding more roads to a system produces more traffic is more people take cars vs. public transit. More precisely, more people take cars vs. not take cars. "Not take cars" can be public transit, human powered transport or even not moving at all.
  - mturmon 12y ago
    This correction might seem pedantic, but I think it is important. One of the lessons of these "paradoxes" (more roads = more congestion) is that one must take into account the whole traffic system. I'd add that another salient factor is people's housing choices relative to jobs and other destinations -- there is an interplay between road-building and housing construction.
- cs702 12y ago
  bigdubs: that video explains the Braess paradox, not the correlation found by the researchers. I modified my comment to make that clearer. Thanks!

adamgravitis 12y ago

Having done some grad work in this area, I'd say this is a fairly superficial take on the topic. This certainly describes one area on the supply/demand curve, and perhaps even a pervasive one given that we essentially stopped building highways 40 years ago, but it's not inherent to the problem. I think it's very possible to jump ahead of this effect, but the capital outlay would be impressive, and as a society we apparently aren't permitted to accomplish Big Things anymore, so it's likely we stay in this weird bit of the function for a long while.

xenadu02 12y ago
Who stopped building highways? In the Dallas area we've been building and expanding them non-stop for decades now. My experience is people have simply moved further out, increasing traffic flowing into the newly expanded/built roads, and overall congestion has remained constant. But I think many of us would agree about accomplishing Big Things. Here's the dirty little secret: the US Government has almost always funded those "Big Things" and taxed the rich heavily to do it. The Interstate highway system was funded by a massive (as a percentage of the price per gallon) gas tax, along with a 90% post-war income tax rate on the rich. Even the trans-continental railroad was funded thanks to guarantees, loans, etc from the US Federal government (including sending the Army out shoot Native Americans and bandits who attacked the railroads). No private entity was willing to take such a large risk - it could have bankrupted even JP Morgan if it went bad. Without "Big Government" support the line never would have been built. I'm all for bringing back much higher taxes on the rich - tax anything over $1 million income at 50%, over $10 million at 60%. Same for cap gains. Use that money to fund massive expansions of roads, build subways under every major city, heck start a government-funded bank that gives anyone who wants to start a business a loan (it's what the Chinese government does). We could do a ton of "Big Things" if we were willing to tax the uber-rich to pay for it.
- ams6110 12y ago
  Taxing the rich simply incents them to behaviors that avoid the tax. Government revenues increased dramatically when the high marginal tax rates were cut. Unfortunately government expenditures increased even more dramatically.

frogpelt 12y ago

I'm a huge fan of toll roads. And I really like charging for use at certain times. Perhaps you could reduce rates for each passenger in the vehicle. Maybe a four-passenger vehicle gets to drive free anytime. This encourages car pooling for those who can't afford to pay the tolls. In fact it may create new jobs.

DINKDINK 12y ago

Driverless cars have the vast vast potential to fix traffic congestion problems. Traffic mainly results from humans' inability to gauge the spacial and speed based tolerances required to prevent braking and as a result sending a backward brake wave through the cars behind it. Add to that fact that there are no game theory advantages to a single driver to driving properly (other than an altruistic realization that if you decide to drive with better tolerances and other people do the same, the congestion is abated)

nulltype 12y ago
That seems dubious. There are a finite number of cars you can get on the road at a given speed. If the total travel time is roughly a constant as this article implies, autonomous cars will be equivalent to adding a few more lanes, meaning there will be no long-term change.
- DINKDINK 12y ago
  Traffic results when car densities pass a certain threshold and the speed the cars are traveling at prevents humans from being able to react in time or appropriately. You might have even seen this phenomenon in real life: Driving on a highway, suddenly you get stuck in traffic. As you pass through the traffic zone, there are no cars pulled over, no accident, no disruption in the quality of road. What most likely happened was that someone accidentally slammed on their brakes which caused an increase in car density. If there are enough cars that are in bound to this traffic zone before the density can disperse, the traffic zone will persist. Also notice that traffic zones often appear in situation where there's a positive increase in elevation. What happens is that if people aren't using cruise control (or their cruise control, control system isn't tight enough) their speed will decrease as they ascend the hill, causing some congestion and as like if the density of traffic is high enough, the cars behind them will have to slow down. You may think that if the cars behind them are also ascending the hill they'll also slow down in the same way but some cars may use cruise control while others don't (resulting in congestion) or the differences in each car's torque, power-output, efficiency curves differ causing each to slow down at different rates (often leading to the least capable car governing the rate) Use a worst-case scenario to analyze. Assume you have a network of diverless cars all linked together that maintain equidistant space between each other. If a new cars needs to join their network / pack the minimum amount of delay that the cars (behind the entering car) need to encounter is the (Length of the incoming car + gap tolerance between the other car) / (the sustained speed of the pack) =25/5280/65*3600 ~= .25 seconds per car. Now do a thought experiment that the high way you drive on was completely full (like we said in our original problem statement) do you think if you added one additional car to the highway, would everyone's (who's downstream of the merge) commute time be only increase ~.25 seconds? I'm very confident it's be much more than that. Traffic management is a task that needs high coordination, cooperation and reaction times above what unassisted humans are capable of.

deleted 12y ago

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skriticos2 12y ago

Well yes, people are irrational. I personally think that a lot of jobs today don't justify driving around at all. What difference does it make if you code in the crowded building of your employer or at home and use tele-conferences to talk with each other? Maybe you would even be more productive if you got rid of all the stress caused by commuting around a substantial portion of the day. I guess a good chunk of the office work done today could be replaced by remote work, but employers insist on everyone to get into the car, commute and thereby congest roads and burn up non-renewable petrol. I am seriously wondering why the working population don't bill the time and expenses of commuting to the employers? Most entrepreneurs do. You pay $50-$100 for the plumber to come to your place (just to come there, work is billed extra). Why not office workers?

phkahler 12y ago

These guys are partially idiots. Obviously there is more demand than road if use is directly proportional to supply as they claim. The problem is the way we design cities and lay out the roads. A regular grid where we put STOP lights? seriously? Go, stop, go, stop. And then we put businesses right on the corners to increase congestion right where it's already bad. When cars get tested for EPA MPG ratings, the average speed on the city drive cycle is slightly under 20mph due to all the stop and go. Hybrid cars get better city mpg than highway by using regenerative braking to recover energy from all that stopping and making drag the dominant factor. I don't think traffic circles are relevant, but designing the layout to minimize disruptions to flow altogether. I've been contemplating this a lot, but can't write it all here right now. Imagine if every drive were 10-20 percent longer distance, but you could average twice the speed over the journey! You'd save gas and time. And if your journey takes less time, that's fewer car-minutes on the road which means less traffic and they could have fewer lanes. The problem is even if we could do the design correctly, nobody is going to build a city from scratch - except in China maybe.

avn2109 12y ago
Building a city from scratch and designing it primarily with private automobile traffic in mind is a textbook case of Doing It Wrong. The only sane approach would be to build a subway (or maybe streetcars that have right-of-way) and then stick a city on top of it.
andys627 12y ago
It seems like you're assuming that the only priority is moving cars around - not walkability or livability. In other words it seems you're assuming the only purpose of the built environment is to move cars. I argue that it isn't and in that case we should measure other stuff besides moving cars efficiently when building our cities.
- phkahler 12y ago
  No, I advocate efficiency as a goal weather it be cars, public transit, or something else. Personally I'd like easy access to both. But public transit is only viable with high density and I don't like the way we do dense either.

sologoub 12y ago

This article seems like a gross oversimplification. There are a lot more variables at play here than just what people tend to do with extra capacity. Terrain and flow dynamics, as well as driver behavior, have a lot to do with it. Take 405 in West Los Angeles for example. On one side it has the Sepulvida pass with very steep decent going south and ascent going north. It is crossed by I-10 going to Santa Monica and Downtown, a little further in 90 goes to Marina del Rey, and then exits for LAX. If you examine this section as an example, you have number of people either trying to get in or pass through this section during commuting hours. From the north, the sepulvida pass makes people slow down as they climb the hill. Not exactly sure why, but many drivers seem to be afraid of it. This recoils through the rest of the traffic, as each incremental car slowing down results in the car behind it slowing down slightly more. Once you get down the hill, you have people exiting and entering with very short distances to decelerate or accelerate, causing more slow downs. On the other side, you have a similar dynamic, but people are also trying to merge to or from 90 and I-10. With majority of the traffic heading either to Santa Monica, West LA, Century City or Hollywood/Downtown/something in between. The city has recently completed a major expansion on the 405 in that area adding a carpool lane, but more importantly changing how you merge to/from several of the exits, including Wilshire blvd and I-10. In my observation, the carpool lane did relatively little, but the smoothed exiting/entering with enough time to accelerate shifted the bottleneck from before Wilshire blvd, frequently spilling past the 90, to no ending around Wilshire. The flow restriction now seems to be the dreaded 101 interchange, with a huge amount of traffic stuck in the Sepulvida pass. As the result, I can not get from the 90 to I-10 in about 10 mins, whereas before it was easily 30. Point being, that if you maintain road size (or marginally improve it) and optimize the flow, you get a lot better returns.

gr3yh47 12y ago
apparently, correlation is equal to causation[1] [1]entire article
- moskie 12y ago
  I don't think that applies. Isn't the point (or one of the main points) of building more roads to make traffic congestion better? The study in this article shows that that doesn't pan out.

lelf 12y ago

The actual paper http://www.ademloos.be/sites/default/files/meccano_docs/The_Fundamental_Law_of_Road_Congestion_Evidence_from_US_Cities.pdf http://www.ademloos.be/sites/default/files/meccano_docs/The_...

chsonnu 12y ago

Unused road space is staring everyone in the face and only a small percentage of commuters are using it: motorcyclists. If you just took 10% of the cars off the road and had them riding and lane splitting instead, congestion would be reduced exponentially. The good news for Californians is that lane splitting is actually legal unlike every other backwards ass state.

DigitalJack 12y ago

I have only read the linked article, not the study, but it seems to me to be a bizarre conclusion that if capacity is increased and utilization remains at maximum, that the capacity caused the utilization. It seems to be a much simpler scenario that demand far outstrips capacity, and until you can meet the demand, saturation every lane added will continue to be saturated. I'm sure amdahl's law applies to lane adding here, on top of the fact that all the highways I've seen merge from one side or the other. I don't think I've seen any that merge in the middle, though I guess they probably exist.

logfromblammo 12y ago

This is exactly the sort of thing that I don't want a politician to read. A study finds a correlation between construction of new roads and increase in driver miles. A policy-maker, never one for logic, transmutes correlation to causation. Now, it may be that they assume that increased demand for travel causes road construction, and assign resources to reduce the total cost for each trip. Good for them. But they may also assume that more roads cause more travel, and decide to prevent trips by destroying roads. Boo. You could as easily prevent water from flowing downstream by building a dam. Then your stream becomes a reservoir, the downstream flow rate reduces while it fills, then the reservoir spills over the dam at the same rate it flowed before. People want to move around. They want to travel freely between the places they can earn money, the places they can spend it, and the places they enjoy keeping their stuff. Making the travel more difficult makes them unhappy, while making it easier makes them more content. For the most part, the desire to move minus the cost of the trip results in economic activity. If that number is zero or negative, people stay put, and don't add to economic circulation. Human movement is an economic engine. You can add friction to it and generate more heat, or you can remove friction and extract work instead Generally speaking, you want people to take more trips, and you want the cost per trip to be as low as possible. That doesn't necessarily mean building more, wider, and longer roads. You may be able to get better results by siting the popular destinations more closely to each other, and ensuring that the routes between them are direct, non-viscous, and non-turbulent. When you do something stupid like make 3000 people work in one building complex, far away from homes or other businesses, and have everyone sleep in a suburban bedroom community, far away from jobs and shopping, yes, the road that is the best available route between them will be packed every single day. You cannot economically reduce traffic by narrowing that road. The cars you see on it will go down, but that is because people quit their jobs or moved their households over the arduous commute. They went somewhere else, and will be earning and spending there, instead. It would be better to simply put the homes, businesses, and offices closer together, and diffuse the obvious trips onto roads in such a way that they are neither over or underutilized.

bcoates 12y ago
> But they may also assume that more roads cause more travel, and decide to prevent trips by destroying roads. Politicians in the city I live in are literally doing this, installing "traffic calming measures" (destroying perfectly good road lanes that were just resurfaced) I believe phase two involves generating clean energy by harnessing the power of Bastiat spinning in his grave.

cyphunk 12y ago

Finally, businesses that rely on roads will swoop into cities with many of them, bringing trucking and shipments. Indeed, roads are most often built to bring in new large corporations that create jobs. Depending on how one measures "quality of life" this could be considered a very good thing. I was expecting something more interesting such as the correlation to car driver behaviour and inefficiency with stop-go traffic when not leaving a buffer in front of the next car (something that was written up very well a year or so ago) and how this logic is effected with wider roads. Instead, got some pretty worn out theories.

transfire 12y ago

What a bunch phooey. Just more peddling of flawed studies to promote increased taxation. If you want to reduce congestion try the obvious. 1) Mixed zoning, allowing more residential and retail to be close together. So people have less distance to travel. 2) Raise speed limits where possible so people can get to their destinations faster. 3) Build for the future. Don't just add a lane or two, add six. 4) And yes trains, do help. The problem in the States is that we hardly have any. Only the major metro areas have any sort of adequate rail system and even they are fairly slow, limited and antiquated. Which brings me to my last point: 5) Consult with Elon Musk.

smutticus 12y ago
Can you please explain how taxation plays into this? Are you implying that decreased investment in roads coupled with increased investment in public transit would increase taxation? What's your argument?
xenadu02 12y ago
I'm sorry but you are simply way off base. When a road is expanded, it does temporarily shorten commute times and reduce traffic. But that makes the cheap land farther away from everything more desirable, causing people to move out further, increasing traffic. Those new suburbs require a massive infrastructure investment to install water, sewer, gas, electricity, etc. Not to mention building surface streets, schools, libraries, shopping centers, etc. We've been building roads at a massive clip around the Dallas area, sprawling out over huge suburbs, many of which support mixed development (as does the city of Dallas itself). When I first moved here, the previous two lane highway had just been turned into a six lane toll road and there were no traffic jams, not even during rush hour. It's been 8 years and now we have stop and go traffic every day for about a 30 minute window and that window continues to grow larger. If you think about the design of roads it should become clear why this happens... You have many on-ramps dumping cars into a fixed set of lanes. If, at any point, there are more cars that want to enter than there is room traffic must slow to accommodate them. In reality it happens before the road is full as people leave space for braking, etc. When that happens at any point, it creates a wave of slowed traffic that begins to ripple backwards from that point, meaning anywhere further backward that is close to capacity begins to jam up, making it even more difficult for new vehicles to enter the roadway, amplifying the wave even more. Even if demand were 100% evenly spread out (which it never, never will be simply by the fact that brand new areas have empty fields or wooded lots - it takes time to build offices, start businesses, etc), the friction of merging & exiting the highway would eventually require more cars to exit than are entering, the exact opposite of rush hour conditions. Building more lanes merely delays the inevitable; that's assuming you can, which in Dallas is impossible - most of the current roads (and 100% of the worst congested ones) would require tearing down skyscrapers or 100% tunneling / elevated highways because there is no more space.

vermooten 12y ago

well duh

nardi 12y ago

So more lanes don't reduce congestion, but this article ignores the fact that they obviously DO increase quality of life, by giving people the freedom to live and work where they choose. We should build more lanes for that reason alone. The reason congestion doesn't get better is simply that there is pent-up demand for driving. The solution isn't "tough luck, adjust your life to fit the traffic." It's to build more lanes, so people can choose to live the life they want to live.

stinos 12y ago
they obviously DO increase quality of life If you only consider the aspect of freedom, maybe. But there are more aspects of quality life to consider imo. Spending hours in a car, practically standing still, causes stress. More lanes? More stressed people, higher volume of traffic jam - is that still freedom, sitting inside a metal cage while you can't go forward or backward? Increased number of cars driving means increased pollution. More lanes means less space for buildings and nature. Etc. I get your point, but I think there is more to it.
- nardi 12y ago
  This argument boils down to: "People don't know what's best for themselves, so we shouldn't give them what they clearly want." I can sympathize with that somewhat, but I think that's a dangerous direction for a government to go in.
Vik1ng 12y ago
Short term maybe, but long term it is really just a waste of resources and certainly not a better life for the next generations. Promoting alternatives outside big cities and spending the money there to attract companies instead of spending it on roads would make much more sense.
baddox 12y ago
> they obviously DO increase quality of life Perhaps not, if you take into account the resource costs of road infrastructure (which are fairly hidden by government) and the health impact of automobile usage (from pollution, commuting hours, and obviously road accidents). The thing is, massive public subsidies for roads might be the reason that so many people need to travel far from their homes to their work. You're assuming that the causal relationship goes one way, but it could just as easily go the other way.

jrobbins 12y ago

I see it as basically Malthusian: people will keep driving until it is so unpleasant that they don't want to do it any more. The tipping point for most people is around 45 minutes. Here's a book with a footnote that mentions that the same 45-minute rule applies worldwide and though out history: http://books.google.com/books?id=uuqIA-ce1CoC&pg=PA408&lpg=PA408&dq=ancient+romans+commute+45+minutes&source=bl&ots=W_4--bDOo5&sig=uNYXKSxadR3pUeZ3epHuKgvI0GQ&hl=en&sa=X&ei=xLGxU-vIHoiTqgaUhIDYDQ&ved=0CDEQ6AEwAg#v=onepage&q=ancient%20romans%20commute%2045%20minutes&f=false http://books.google.com/books?id=uuqIA-ce1CoC&pg=PA408&lpg=P...

CamperBob2 12y ago

Then clearly we can make traffic flow more smoothly by shrinking existing roads. Right? What? No? It doesn't work that way? Hmm, what a coincidence, it appears we're already at the sweet spot on the traffic-flow Laffer curve. Either that, or what the authors of the study are trying to optimize is very different from what the typical driver is trying to optimize.

fataliss 12y ago

I wish, LA had a good public transportation network but it doesn't. I used to take the bus, I had to change twice and spend at least 1h traveling, while it takes me 12 to 20min using my car (20min on exceptionally busy days). It probably is one of biggest city that doesn't have an underground metro! I guess that's one of the rare thing I miss from NYC. Being able to move fast without owning a car!

baddox 12y ago

It's an interesting effect, and fairly obvious once you hear the explanation the first time. This article focuses primarily on the effect that roads have on their own congestion, but I think you can do similar analysis on the effects of roads on many other things. This sort of idea is discussed a lot in the libertarian community. I don't intend to make the conversation about that; I just want to mention the ideas because they're similar. Basically, a common and oft-parodied criticism of libertarianism is "but who will build the roads," implying that massive road infrastructure is something that can only be produced by government through taxation and eminent domain. One common retort by libertarians is to come up with a bunch of proposals for how private enterprise could create a very similar road system to what we have today. I think that's the wrong approach. I'm more interested in the ways that government roads, no matter how well-intended they are, can lead to inefficiency and perverse incentives. I think the biggest and easiest argument to make is an environmental one, which is somewhat ironic, considering that libertarians are generally considered (by themselves and others) as a threat to environmentalism. And yet, I wager that public road infrastructure is one of the most obvious cases where government programs lead to (probably unintended) environmental problems. The interstate highway system is a massive blow to railroads, which have a vastly smaller environmental impact than road freight. The public road funds essentially subsidize the price of fast shipping via truck. Big trucks are probably responsible for a disproportionately large portion of road wear relative to the funding of roads that they provide. Another interesting effect is that urban sprawl probably wouldn't happen without roads which are primarily produced by government. This is probably another big threat to the environment, since I would imagine that suburbs pollute much more per capita than urban areas because of the necessity to use automobiles.

mjburgess 12y ago
I think the "roads" problem is just a simple and easy example of the general class of collective action problems that require a single authority to manage. Here is another example: the design of a network cannot be modified arbitrarily. It's rational for a private company to insert a road into a system to benefit itself at the disadvantage to others (cf. negative externalities). Indeed it's rational for several to do this making ad-hoc modifications to the network, the net result of this is significant inefficiency. Collective action problems and (negative) externalities are the main cases where we require a single-point-of-trust / authority to coordinate a system. Libertarians say that private companies can do this, but when you ask "well what do these companies look like?" you invariably get something like a small government. The moral question then arises: we have these single-points-of-trust, do we have any democratic control over them? The answer, in a libterian system is No (money != vote). The libertarian solution to these problems then, seems to me, to hand them over to private tyrannies with no public accountability to perform largely the same function as a government. Its at this point the "NOPE!! LEAVE ME ALONE!" tends to come out.

dasil003 12y ago

I witnessed a nice microcosm of this demonstrating how fast the shift occurs. Every day I cycle commute up the London A24/A3 (CS7) corridor. On the first day of the first tube strikes early this year, the congestion was insane. I mean the worst traffic I've ever seen in my life. An ambulance was literally stuck in traffic and no one within earshot of the ambulance able to move their vehicle enough for it to get through. But then the second day of the strike traffic was a bit on the heavy side but mostly back to normal. I think a huge number of people realized that it was actually pointless to even attempt to go to work unless they were walking or biking. This effect even carried over to the second tube strike a month or two later.

tunesmith 12y ago

It's interesting that they make the point that congestion pricing will induce people to take alternate routes. The recent update to Google Maps seems to do the same thing. It's much more proactive now about suggesting alternate routes. Here in Seattle, I recently bypassed I-5 by taking an astonishingly complex and twisty route that was all prompted by Google Maps, and I got to my destination five minutes sooner than Google was estimating I would had I stayed on I-5 (although that's impossible to verify since traffic congestion changes throughout the duration of a drive). All that said, while it was fun (also especially when I avoided a Tacoma I-5 snarl that I hadn't previously known how to avoid), I don't think we actually want to redirect highway drivers onto local streets. Local streets aren't designed for highway overflow; they're designed for local traffic. Isn't the real answer to design more decentralized town areas so people have less reason to drive long distances, for reasons other than recreation?

joeguilmette 12y ago
sounds like a great solution to the problem if you have the luxury of solving it before it is a problem. i don't think that demolishing and rebuilding the metropolitan Seattle area is a viable solution to the traffic issues that area faces.
judk 12y ago
Try the math. For a given number of people, centralizing reduces everyone's commutes. The key is to not separate housing from commerce and business.

anoxic 12y ago

This actually makes sense in an unintuitive way.

legohead 12y ago

I've always thought something is definitely wrong with the way we think about roads when car pool lanes end up just as busy/gridlocked as the rest of the road.

zmmmmm 12y ago

Yet when I visit a small country town with a giant road through the middle, there is still no traffic there. If big roads induce traffic independent of any other factors then this should not be true - the mere presence of the big road should have created traffic. While I understand there's a really point to this paradox (it really happens), I hate the simplistic conclusion people reach that it is always wrong to make a road bigger. Sometimes you really do need a bigger road. Sometimes you really need more public transport or something else. It's complicated, and we need better models of it. But reducing it to one line slogans doesn't help that.

nickonline 12y ago
That's kind of the point made about halfway through the article where he states if you expand a road to 100 lanes you won't ever see any traffic. In those country towns with a population of 30,000 but a super road through the center that could carry 100,000 people a day the road _is_ the same as if that 100 lane highway had been built in a major city. In the article they state that there are more factors at work but they do need a title for the article that will draw people to read it.
- astrodust 12y ago
  I think highways like the 401 in Toronto prove that the "100 lane" theory is pretty much bullshit. https://en.wikipedia.org/wiki/Ontario_Highway_401 https://en.wikipedia.org/wiki/Ontario_Highway_401 It's arguably the busiest highway in North America based on a number of metrics, even more volume than LA's perpetually busy Santa Monica Freeway. They've been expanding it ever since they've built it and in parts it is 25 lanes wide. It's slammed all the time. Traffic jams at 3am aren't unheard of if they're doing road work and it's slimmed down to half capacity. It was once merely an 8 lane highway, so the idea that tripling or quadrupling the size of a highway magically makes traffic jams go away is so far from the truth. There's a parallel highway running north of it that's paid by tolls which isn't as busy, but only because they can adjust pricing according to demand.

bane 12y ago

I feel like there's a cause and effect relationship being presented here that isn't necessarily true, even if the correlation is true.

uint32 12y ago

Also: bigger/faster computers makes programs bloated/slower.

aaron695 12y ago

This article is rubbish > What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse > For instance, Paris in recent decades has had a persistent policy to dramatically downsize and reduce roadways. “Driving in Paris was bad before,” said Duranton. “It’s just as bad, but it’s not much worse.” Bigger roads are worse, and smaller roads are worse? There's a point here somewhere but they've failed to make it.

emj 12y ago
I guess they get more foot traffic, and living streets (more shopping/social life etc). If you get that and less cars in traffic I guess I see a win there.

drawkbox 12y ago

Sounds a bit like Parkinson's Law: http://en.wikipedia.org/wiki/Parkinson's_law http://en.wikipedia.org/wiki/Parkinson's_law "The demand upon a resource tends to expand to match the supply of the resource."

brianstorms 12y ago

This is nothing new. Read Robert Caro's 1974 Pulitzer Prize-winning book THE POWER BROKER if you wanna know about roads and highways and freeways and how expanding them only makes traffic worse.

_Adam 12y ago

The article fails to follow the logical process to the very end. What isn't being asked is: why are humans using that road when they weren't using the smaller road before? Humans don't just drive for the sake of doing so. They drive because they have the need to do so. Building roads lowers the perceived time cost of driving, so more people drive, and more people drive at the time that is most desirable to do so. In some cases this results in increased congestion, but if the need of the population is met or exceeded, then the result is smooth traffic flow. Even if the bigger road is more congested, it may still have a greater net traffic flow, and that increased flow results in greater economic and societal good. For example, because of new highway XYZ, I can now work somewhere that was formerly too far a commute. The problem isn't solved by building smaller roads, it's solved by building even bigger roads, or building roads in a more optimal fashion (selecting a route for a new road that matches the transportation needs of the population).

Corrado 12y ago

What about a smartphone app that helped you avoid the most congested roads. I think Waze does something like this today and I'm sure that Google Maps can as well. We just need to have it integrated into the system so that we don't have to think about it. I think this is where projects like Andriod Auto & iOS CarPlay come into play. Just jump into your car and say "Take me to Julia's house" and the route will be mapped out for you. I would love to not have to figure out the best way to get to the mall on a busy Saturday afternoon! Even better, an auto-driving car will actually take care of the moving bits as well as planning your route.

peter_l_downs 12y ago

Funny to see this on the HN frontpage – the Downs who originally suggested the "fundamental law of highway congestion" being confirmed in the paper [0] is my grandfather. Thanks for submitting this, it's very interesting work. [0] http://www.nber.org/papers/w15376.pdf http://www.nber.org/papers/w15376.pdf

duncan_bayne 12y ago

Counterargument here: http://pc.blogspot.com.au/2014/06/more-roads-doesnt-mean-more-traffic-jams.html http://pc.blogspot.com.au/2014/06/more-roads-doesnt-mean-mor... "By comparison, building expensive transit systems aimed at getting people out of their less-expensive cars generates zero economic benefits if it generates no new travel. Only new travel generates economic benefits, so people who argue that new roads induce new travel are actually arguing that new roads create economic benefits. If congestion is the issue, then–as Mann briefly mentions–the solution is congestion pricing. But Mann doesn’t understand the difference between true congestion pricing and New York City’s proposal for cordon pricing. Cordon pricing is more a way of raising revenue to fund urban boondoggles than a way of relieving congestion. Even UC Berkeley planning professor Robert Cervero believes that the induced demand argument is “wrong headed.” “Road investments by themselves do not increase volumes,” he writes. “Only by conferring a benefit, like faster speeds, will traffic increase.” Provided that benefit is greater than the cost–something that could be assured, Cervero says, through proper pricing of roads–then it is a good thing."

StillBored 12y ago

I think studies which measure traffic congestion in the US based on road building over the last couple decades IMHO are flawed. That is because I believe how and where you build the road is more important than how much road you build. For example, where I live the main roads in the city proper haven't been upgraded in the last 40 years. Yet, new roads funneling drivers from farther and farther out are being constructed all the time. This simply means that the first 1/2 of many drivers commutes involves sailing along a new road until they hit the old roads, and then puttering around at 5mph (or worse) for the last 5-10 miles of the journey.