20 ms·

A broken algorithm that affected American transportation

71 points by panic 6y ago

throwawaysea 6y ago
This article repeats a common flaw, which is citing the theory of “induced demand”. This is merely rhetorical framing. Demand isn’t induced, but fulfilled. And it is a good thing, because that’s what those drivers want - to make their trips easily, which is what road infrastructure enables. The notion that increased road infrastructure will magically hold congestion steady or worsen it is laughable. It just means demand hasn’t been satisfied yet. Clearly a 1000 lane highway would not be congested, so there is some finite and lower number where demand balances out with supply. This is no different than supply and demand in any other situation, which is why the label of “induced demand” is without meaning and simply a rhetorical device.
- adrianN 6y ago
  You're missing the fact that more space allocated to roads and parking moves the things people actually want to do farther apart, increasing the need for more roads and parking. People don't want to drive, they want to get to places. That's the actual demand that needs to be satisfied. Cars don't scale very well to do so. You can't realistically build roads in cities that can move the same number of people as a subway line. If you did you wouldn't have a city anymore, you'd have a parking lot with some buildings sprinkled across it.
  - AnthonyMouse 6y ago
    > You're missing the fact that more space allocated to roads and parking moves the things people actually want to do farther apart, increasing the need for more roads and parking. But if this is your concern then the thing that really moves the things people actually want to do farther apart is low density zoning requirements. Which is also the thing that keeps mass transit from being viable, because it needs enough population density to fill the vehicles while still offering frequent enough service to be competitive.
    - emn13 6y ago
      That's too simplistic; you can't pin the blame on a singular effect like that nor choose to disregard other factors to conveniently support some conclusion. It is incidentally clear that low density zoning requirements are not the singular driving factor for sprawl simply because the sprawl occurs even in places without those rules (e.g. houston). Furthermore, effects like these have complex feedback loops. Zoning laws are entirely politically motivated - so the public's support is critical. You can be sure that public support would be affected if it became clear they led to crippling congestion that would not be solved by more road infrastructure; and conversely sprawl-encouraging zoning laws also encourage sprawl-enabling transport investments. Other factors to consider are parking availability (and rules concerning that), and probably more. The correlation between these effects means that you should be careful blaming just one factor, and certainly cannot conclude anything meaningful if you intentionally and artificially exclude related factors from your analysis.
    - anonymoushn 6y ago
      In downtown Austin, many uses are placed next to each other and density is fairly high, but half of the blocks are allocated to parking. So somehow the things people actually want to do are moved far apart by factors other than low density zoning.
- wahern 6y ago
  > This is no different than supply and demand in any other situation It's different because highway usage is free. Demand is induced because you're giving away something for free. Demand plateaus when the costs (i.e. traffic) rise to the previous levels. Image if SpaceX started giving away free rides to Mars. Millions of people might go. But what if they charged a price equal to the actual costs--manufacture of the spaceship, fuel, etc? The cost would be ridiculously high and only a tiny handful of the richest people would go. Those handful of people represent actual demand where it meets the supply curve. The difference between those willing and able to pay, and all those willing to go if free, is the induced demand.
  - 01100011 6y ago
    That's not practically the case though. Road usage costs gas, including taxes, and maintenance.
    - jacobush 6y ago
      Depending on where you live, you might already eat most the car associated costs as part of living. EVs are only going to make it worse, with higher fixed costs and lower marginal.
      - TeMPOraL 6y ago
        A complete tangent, but when I read "you might already eat most the car" I mentally put a full stop here and realized that this is true to an extent: if you live close to a place with large traffic, you're quite literally eating (or at least breathing in) cars, in the form of tire and brake dust. So that's another, non-monetary, cost of living you have to pay.
    - wahern 6y ago
      Sure, and going to Mars has its own costs, like cancer risk or forgoing a trip to Disney Land, even if a ticket is free. The point is that to the extent people don't have to internalize the actual cost of the product or service, demand will be higher. And this difference is what's being referred to as induced demand in the context transportation policy. None of this means that new infrastructure can't create a richer, more productive environment.[1] Obviously the real world is more complex. But the pathological phenomena of induced demand in especially clear and substantial for highway construction because of the process for choosing, designing, and budgeting projects. And to the extent the actual costs are born by the individuals voting for and using a new highway, the linkage is particularly weak and distant and so the costs don't moderate the demand as should normally happen in well-functioning markets. When you try to bring them closer, say through tolling, people become apoplectic; "That's what my taxes are paying for!", etc, ignorant of the point that costs don't moderate consumption very well unless the relationship is clear and obvious--usually the more immediate, the better. [1] Though that's why the article criticizes reliance on modeling, because at the end of the day the choice is less about planning for an inevitable future than picking & choosing among potential futures, each with costs & benefits that are difficult to quantify independent of policy goals--equity, sustainability, mobility, etc.
- sideshowb 6y ago
  This isn't physics and it isn't an exact equilibrium, but within the range of highway sizes we actually have (not your 1000 lane hypothetical) it seems to hold. Not only do people drive more, but more origins and destinations get built to take advantage of new transport links.
  - AnthonyMouse 6y ago
    That's because the existing demand is highly under-satisfied, as evidenced by the existing traffic congestion. In theory you could actually satisfy all of it by building a thirty lane triple-decker highway and it would work. Of course, that's still stupid, because what you should do is build a normal highway (e.g. add a lane or two) to absorb some of the demand, and absorb more of it in other ways, as with mass transit or increasing zoning density so that people can live closer to their destination.
    - anonymoushn 6y ago
      Increasing zoning density doesn't help much if it's still illegal to build a grocery store or a coffee shop anywhere near an apartment complex (and the other way around, too)
  - iso947 6y ago
    A 1000 line highway would take tens of minutes, maybe upto an hour, to drive to the outside lane, it would have its own interesting traffic problems.
    - TeMPOraL 6y ago
      I can imagine you'd want to split it e.g. into 250 4-lane tracks, with the leftmost track being reserved for people going all the way to the end of the highway, rightmost track for people who're about to exit the highway, and the middle tracks for people traveling to various points along the highway path, sorted left-to-right by distance, descending. Otherwise it would be just one huge mess.
- doktorhladnjak 6y ago
  This overlooks that roads take up space and other resources. If you build or expand a road, that's something else you can't build or expand (housing, offices, parks, schools, etc.) there. Moreover, who wants to live next to a busy freeway? Noise and air quality aren't great. In the 1000 lane situation, people can get where they want, but where is it that they're going to if the fraction of space is mostly roads? You can see the practical limits of pushing for more, wider roads at scale clearly in Los Angeles. A massive grid of wide freeways. Long commutes. Bad traffic even outside rush hour. Auto dependency. Air pollution. High household transportation costs.
sideshowb 6y ago
Pre 2000s transport planning is a textbook study of optimizing for the wrong thing. Although it failed to reduce congestion you could argue the extra trips contributed to GDP... but that's subject to the same problem... Ultimately what is the correct metric though? Well being? https://www.mdpi.com/2071-1050/12/8/3180/htm# https://www.mdpi.com/2071-1050/12/8/3180/htm#
KingMachiavelli 6y ago
As some others have mentioned, I don't think that induced demand or the failure to prevent congestion are failings of the model itself. A congested 5 lane road still has a higher throughput than a congested 2 lane road. However, the largest problem I see which the article briefly touches on is the failure to even consider building something besides a freeway. A `correct` model should be screaming to build public transport. However, consider the following circumstances: 1. As it is many people are forced to have a car even if public transport can serve their main commute but often public transport is more expensive than the marginal cost of driving a vehicle (i.e gas + upkeep) so they choose to drive unless the congestion is extreme (i.e one of the worst commutes in the US). 2. Even if public transport is pretty decent (commute + groceries), they just happen to already have a car because their previous location did not have public transport. So we are back at #1. Or I don't know if I'll move in a year or two so might as well keep the car. 3. OR now that I have a car , I would probably not want to have to pay for expensive parking (& housing) in an area with public transport plus now I'll have to pay a mechanic a premium to even change the oil. So instead I live further away thus reinforcing the need to keep the car. 4 & etc. I need to travel >50 miles (skiing, hiking), renting is a pain and long trip ride sharing is expensive. Groceries are easier to do with a car especially when buying in bulk (Although, if/when I can get Costco delivered same or 2-day with perishables at <=10% premium, then this is a moot point). Cars are pretty (at least marginally or per mile) cheap in America and we do a very poor job making the alternatives attractive if not impossible. Anyone who has a car seems to drive it even if public transport could be used (again outside of super specific commutes in a few cities). Until we can either make car ownership/use more expensive or greatly increase the practicality of not having a car at all, anticipate having a car and being stuck in traffic at least part of the time.
- lotsofpulp 6y ago
  Hence drastically raising taxes on fossil fuels. The environmental costs of fossil fuels are nowhere close to being represented in the cost of fuel people pay, therefore we have this massive misallocation of resources. But then society will have to vote for sacrificing luxury today for the benefit of future generations, which typically doesn’t go well.
mehrdadn 6y ago
Some more reading: https://en.wikipedia.org/wiki/Induced_demand https://en.wikipedia.org/wiki/Induced_demand > City planner Jeff Speck has called induced demand "the great intellectual black hole in city planning, the one professional certainty that everyone thoughtful seems to acknowledge, yet almost no one is willing to act upon."
- mattmcknight 6y ago
  That's bizarre, because I see it as the most overused argument over the past 25 years! People oppose any lane additions with induced demand.
ArkVark 6y ago
Hub and spoke public transport is dead. It relies on huge infrastructure investment and open access. The future is autonomous minibusses with algorithmically-derived live routes, served on a subscription basis by private companies to private individuals. This way people of similar socioeconomic status can rub shoulders with eachother and feel more comfortable, and receive a greater standard of service. It might very well be necessary to modify roads and road rules to facilitate autonomous vehicles - that's the kind of public investment we should be making.
- knolax 6y ago
  > This way people of similar socioeconomic status can rub shoulders with eachother and feel more comfortable, and receive a greater standard of service. That's a lot of work just so you can avoid being near poor people.
- pjc50 6y ago
  This ends up unreasonably expensive unless subsidised by loss-making VCs.
  - ArkVark 6y ago
    It ends up like an Uber, but cheaper since you have no driver and are sharing the vehicle with other passengers.
    - dmitriid 6y ago
      And Uber is endlessly subsidized by loss-making VCs. Uber has been losing billions of dollars every year.
      - colinmhayes 6y ago
        Uber made money this year if you take uber eats out of the equation.
        6y ago
sradman 6y ago
> population and land-use patterns... are two of the most important variables in any TDM [Travel Demand Model] All models are based on assumptions. Revisiting those assumptions should be a continuous process that forms a tight feedback loop, especially given the long timelines and large capital costs involved with civil infrastructure projects. If population and land-use assumptions are the key factors then the important questions should be how these assumptions will be validated and how often. These questions seem to be missing from the article.
aaron695 6y ago
The article actually begrudgingly admits the model works fine. It's nice they are honest for a change, normally they just factoid it away. And concludes it's politics. Not sure if I read the same article as everyone else?
renewiltord 6y ago
These big projects aren't about actually solving problems. They're a combination of public works projects and returning money to your political investors. So you choose the project then construct the justification. Because the true confidence interval is really large, you can go either way. If you're good about it, you can drag the project out with delays but with milestones you can talk about politically. Then by the time the project has been discovered to have been unnecessary you're out of power and it's no longer a problem. And your investors have a good return to invest in the next guy to give them the next project.
- sthnblllII 6y ago
  I think a lot of Americans are still in the world war 2 generation mindset about the US being corruption-free. The truth is that corruption at every level has gotten steadily worse throughout the last century, but the culture hasn’t yet changed to be vigilant of it, probably because most Americans are very honest themselves.
  - renewiltord 6y ago
    I think that's it, honestly. I think this relatively high-trust culture that Americans have actually makes the society pretty efficient and it's much more pleasant to live in. But it has none of the anti-bodies to the kind of cynical corruption that many other countries find endemic. And so when it came here, America had no defence. Because the host is still so healthy, it still doesn't realize it is carrying this parasite. It'll be interesting to see what happens when the host becomes unhealthy.
massysett 6y ago
Ironically this article exposes the fallacy of “induced demand.” Proponents of this mindset, such as the author of this article, claim that more lanes inevitably lead to more traffic. But the article leads off with an example of a massive highway expansion project that is a “boondoggle” because traffic fell and the lanes are empty. I thought that lanes automatically fill up, because induced demand.
- deleted 6y ago
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- xsmasher 6y ago
  Travellers shift from other modes of transit until the "pain levels" even out again; that's independent of the travelers drying up altogether for other reasons though.
- nimbleal 6y ago
  Surely, unless the claim was that in all cases, everywhere a new road means new levels of traffic to fill it, a single counterexample does nothing to expose a fallacy? I feel like your “inevitably” here is a bit strawman-y
rikroots 6y ago
I met another faulty transport planning algorithm 30 years ago. Background: my first job in the UK Civil Service was as an admin assistant (I did the filing) in the Highways Contracts division, Dept of Transport. My team's job was to let the contracts for developing plans for new/improved national roads across England. The Algorithm: roads cost a lot of money to build; every proposed route had to demonstrate significant value for money through a cost-benefit analysis for each project, considering a number of different detailed options for the new or improved road. One of the main costs was how much money needed to be spent on buying and securing the land, and compensating the owners for loss of business, etc. In cities and towns, this favoured putting bypasses through the poorer parts of the (sub)urban environment. In more rural areas it favoured routing roads through less productive farmland. The least productive land was land that wasn't being farmed or mined. Routes put through these areas would be given an acquisition cost of £0/meter[1] ... Which is why in 1993 the Government settled on developing an improvement scheme for the A303 which put a new double-lane carriageway straight through the middle of Stonehenge. The proposal didn't go down too well. 30 years - and several administrations - later, the Government is still trying to get the proposal through planning[2] [1] - Though in fact highway lengths were still measured in 'chains' and 'links' back in the early 1990s: https://en.wikipedia.org/wiki/Chain_(unit) https://en.wikipedia.org/wiki/Chain_(unit) [2] - Current proposal for the project: https://assets.highwaysengland.co.uk/roads/road-projects/A303+Stonehenge/Environmental+Non+Technical+Summary.pdf https://assets.highwaysengland.co.uk/roads/road-projects/A30...
nicolaskruchten 6y ago
I broadly agree with the article, but one point where it falls short is that it doesn't mention that the 4 stages of the model can be (and sometimes even are!) iterated in various ways to account for the way real people actually behave: modellers in the 21st century aren't quite as naive as all that (and probably the ones in the 50s weren't either but they had less data/computer power). For reference, the four stages go like this: you start with "trip supply and demand" by zone, then inter-zone trips are generated by matching those up, then mode choice is computed per trip based on cost and travel time priors, then assignment to the network which results in actual trips and computed travel times based on route selection and congestion. The travel times can then be fed back into mode-choice and iterated on: people will make the transit-vs-car choice differently based on the relative costs (in time and money and inconvenience) so iterating the last two steps can go a ways towards modelling that equilibrium. Folks can exert some amount of choice around which trips they make (as mentioned in the article) and where they work, based on how easy it is to get there, so feeding the travel costs back into trip-generation can account for some of that, and over a longer horizon, both workers and employers can exert some control over where they live/site their facilities, so all 4 stages can be iterated as well. None of this is perfect, and it's not always done, and the rest of the article's points stand, but I just wanted to say the modelling is not all that primitive :) Edit: I studied this stuff in university 15 years ago with Professor Eric Miller, who wrote this book on how to integrate all this stuff in an iterative way... https://link.springer.com/article/10.1007/s11067-005-2630-5 https://link.springer.com/article/10.1007/s11067-005-2630-5
DoreenMichele 6y ago
The interstate system dates to 1956.[1] So it is part of the set of mental models that haunt the US and continue to poison our built environment. The post-WWII era is the same era that gave birth to the modern suburb and the Baby Boom, giving us the Baby Boomers. Americans have been basically brainwashed into thinking that patterns of development from that era are right and good and so forth and then we put those models on steroids and do more of that same. Our suburbs began as houses of around 1200 sq. ft. Last I saw stats, the average new home in the US was over 2400 sq. ft. (though a recent private conversation with a professional urban planner suggests those figures may finally be dropping). We need an entirely new set of mental models, something I think of as "the butterfly economy" based on a comment I made on HN once.[2] There is a potential path forward, but we aren't going to take it because that would involve listening to a woman and this will not happen. This is a hill our current world is eager to die upon, so we will remain haunted by the ghosts of Christmas past -- prisoners of mental models that served our parents and grandparents extremely well, so they got burned into our collective psyche as the only good way to do anything and never mind that the world has changed and all of that is very much out of date. I'm short of sleep, tired of getting zero respect, underfed (as is the norm late in the month), in a generally bad mood over how my crappy existence remains crappy largely due to sexist BS and no amount of pointing out the sexist BS causes it to really budge. So I think that's all I'm going to say here since I fully expect to get kicked in the teeth for saying anything and I've had quite enough abuse for one life. [1] https://www.fhwa.dot.gov/interstate/interstatemyths.cfm https://www.fhwa.dot.gov/interstate/interstatemyths.cfm [2] https://news.ycombinator.com/item?id=22028732 https://news.ycombinator.com/item?id=22028732
rmrfrmrf 6y ago
Not shocking at all that Vice would frame an algorithm designed to create construction jobs via federal funding as "broken" and "poisonous".
- deleted 6y ago
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thehappypm 6y ago
Public transportation should really just be bus-based. Every city that has a large public transit system — worldwide - spends an absolute fortune on trains, track maintenance, overhead lines, operators, and so on. Even shiny European systems are hugely hugely expensive. They often use a wide variety of approaches — Boston for example has about a half dozen completely incompatible rolling stock. Buses can be deployed and scaled cheaply, routes can adapt quickly, dedicated bus lanes can be built with paint and not tunnels. Choke points can use dedicated right-of-way and electric infrastructure can go into tunnels with far less ventilation need. Buses can handle a fallen tree by driving around it. Buses don’t need special tracks to take them to depots. A down bus doesn’t back up the buses behind it. The list goes on and on.
- currymj 6y ago
  do you have any thoughts on what causes these systems to stick to trains? to me, as a user of public transit, they just seem somehow more pleasant, in a way I can't really make sense of. I strongly dislike riding in buses and try to avoid it, whether part of transit systems, Greyhound/Peter Pan, or even high-end charter buses. maybe if you had electric (no exhaust, quiet) buses with frequent reliable service, dedicated lanes almost everywhere, nice bus stops without hostile architecture, I wouldn't feel such a strong preference, but I'm not sure. I'm wondering whether it's not just that I subconsciously dislike getting jostled around and feeling slightly carsick.
  - thehappypm 6y ago
    I think perception is the largest part. The word “bus” conjures up a dirty, homeless-guy horror show to a lot of people, compared to the quiet elegance of a train conductor peacefully snipping your ticket in a leather chair. Second, in many cities, trains actually predate the highways. Third, trains have super high capacity, as do subways and light rail. You need more buses to keep up. However, buses are cheap, and there are things like extra-long articulating buses and double-deckers that can be used on high-volume or long-haul routes. I think buses actually have a practical edge here: instead of trains coming every hour, you could have a big bus come every 10 minutes, which smoothes out load at end stations. And if one breaks down, the other buses can just drive around it. If a subway breaks down in New York, it can cause delays that ripple out to the whole system.
brundolf 6y ago
This kind of complex-system-optimization problem seems ripe for improvement via machine-learning. Cases where 1) precisely modeling the outcome is totally intractable, and 2) you really just need to get "close enough" to get good results. It also helps that this case is predictive in nature (so it's easy to go back and measure accuracy) and has an enormous set of available training data (all traffic happening everywhere across the country). It feels very similar in spirit to that story about Google reducing data center energy use by 40% via ML optimization: https://deepmind.com/blog/article/deepmind-ai-reduces-google-data-centre-cooling-bill-40 https://deepmind.com/blog/article/deepmind-ai-reduces-google... More broadly I've started wondering if there's a huge opportunity to apply software to civil improvement. Everything from detecting patterns of corruption, to aggregating data that can inform voters, to identifying sources of inefficient spending. I don't put much stock in things like digital voting/governance, but in the area of "data crunching and presentation" I think there's a lot that could be done.
- nicolaskruchten 6y ago
  > an enormous set of available training data (all traffic happening everywhere across the country). I'm not sure this is very helpful to predict traffic patterns over the next 20-30 years in a policy-sensitive way... All the historical data in the world wouldn't have predicted the rise of Uber, the pandemic, the maybe-eventual rise of self-driving cars etc.
  - brundolf 6y ago
    True, but it doesn't sound like the approach described in the article factors in extraordinary circumstances like that either
    - nicolaskruchten 6y ago
      The model won't tell you how likely these scenarios are, but one advantage of this class of model over black-box ML function-fitting is that you can do scenario planning. You can do models runs like "what happens if the price of oil shoots way up?" or "what happens if 50% of the cars are taxis?" (e.g. Uber-driven future) or "what happens if transit all of a sudden gains a huge perceived cost?" (e.g. respiratory-virus pandemic) in the third and fourth stages of the model. In the early stages of the model you can look at stuff like "what happens if firms abandon city centers?" or "what happens if 50% of white-collar work is done from home?" etc.

71 points by panic 6y ago

This article repeats a common flaw, which is citing the theory of “induced demand”. This is merely rhetorical framing. Demand isn’t induced, but fulfilled. And it is a good thing, because that’s what those drivers want - to make their trips easily, which is what road infrastructure enables. The notion that increased road infrastructure will magically hold congestion steady or worsen it is laughable. It just means demand hasn’t been satisfied yet. Clearly a 1000 lane highway would not be congested, so there is some finite and lower number where demand balances out with supply. This is no different than supply and demand in any other situation, which is why the label of “induced demand” is without meaning and simply a rhetorical device.

adrianN 6y ago
You're missing the fact that more space allocated to roads and parking moves the things people actually want to do farther apart, increasing the need for more roads and parking. People don't want to drive, they want to get to places. That's the actual demand that needs to be satisfied. Cars don't scale very well to do so. You can't realistically build roads in cities that can move the same number of people as a subway line. If you did you wouldn't have a city anymore, you'd have a parking lot with some buildings sprinkled across it.
- AnthonyMouse 6y ago
  > You're missing the fact that more space allocated to roads and parking moves the things people actually want to do farther apart, increasing the need for more roads and parking. But if this is your concern then the thing that really moves the things people actually want to do farther apart is low density zoning requirements. Which is also the thing that keeps mass transit from being viable, because it needs enough population density to fill the vehicles while still offering frequent enough service to be competitive.
  - emn13 6y ago
    That's too simplistic; you can't pin the blame on a singular effect like that nor choose to disregard other factors to conveniently support some conclusion. It is incidentally clear that low density zoning requirements are not the singular driving factor for sprawl simply because the sprawl occurs even in places without those rules (e.g. houston). Furthermore, effects like these have complex feedback loops. Zoning laws are entirely politically motivated - so the public's support is critical. You can be sure that public support would be affected if it became clear they led to crippling congestion that would not be solved by more road infrastructure; and conversely sprawl-encouraging zoning laws also encourage sprawl-enabling transport investments. Other factors to consider are parking availability (and rules concerning that), and probably more. The correlation between these effects means that you should be careful blaming just one factor, and certainly cannot conclude anything meaningful if you intentionally and artificially exclude related factors from your analysis.
  - anonymoushn 6y ago
    In downtown Austin, many uses are placed next to each other and density is fairly high, but half of the blocks are allocated to parking. So somehow the things people actually want to do are moved far apart by factors other than low density zoning.
wahern 6y ago
> This is no different than supply and demand in any other situation It's different because highway usage is free. Demand is induced because you're giving away something for free. Demand plateaus when the costs (i.e. traffic) rise to the previous levels. Image if SpaceX started giving away free rides to Mars. Millions of people might go. But what if they charged a price equal to the actual costs--manufacture of the spaceship, fuel, etc? The cost would be ridiculously high and only a tiny handful of the richest people would go. Those handful of people represent actual demand where it meets the supply curve. The difference between those willing and able to pay, and all those willing to go if free, is the induced demand.
- 01100011 6y ago
  That's not practically the case though. Road usage costs gas, including taxes, and maintenance.
  - jacobush 6y ago
    Depending on where you live, you might already eat most the car associated costs as part of living. EVs are only going to make it worse, with higher fixed costs and lower marginal.
    - TeMPOraL 6y ago
      A complete tangent, but when I read "you might already eat most the car" I mentally put a full stop here and realized that this is true to an extent: if you live close to a place with large traffic, you're quite literally eating (or at least breathing in) cars, in the form of tire and brake dust. So that's another, non-monetary, cost of living you have to pay.
  - wahern 6y ago
    Sure, and going to Mars has its own costs, like cancer risk or forgoing a trip to Disney Land, even if a ticket is free. The point is that to the extent people don't have to internalize the actual cost of the product or service, demand will be higher. And this difference is what's being referred to as induced demand in the context transportation policy. None of this means that new infrastructure can't create a richer, more productive environment.[1] Obviously the real world is more complex. But the pathological phenomena of induced demand in especially clear and substantial for highway construction because of the process for choosing, designing, and budgeting projects. And to the extent the actual costs are born by the individuals voting for and using a new highway, the linkage is particularly weak and distant and so the costs don't moderate the demand as should normally happen in well-functioning markets. When you try to bring them closer, say through tolling, people become apoplectic; "That's what my taxes are paying for!", etc, ignorant of the point that costs don't moderate consumption very well unless the relationship is clear and obvious--usually the more immediate, the better. [1] Though that's why the article criticizes reliance on modeling, because at the end of the day the choice is less about planning for an inevitable future than picking & choosing among potential futures, each with costs & benefits that are difficult to quantify independent of policy goals--equity, sustainability, mobility, etc.
sideshowb 6y ago
This isn't physics and it isn't an exact equilibrium, but within the range of highway sizes we actually have (not your 1000 lane hypothetical) it seems to hold. Not only do people drive more, but more origins and destinations get built to take advantage of new transport links.
- AnthonyMouse 6y ago
  That's because the existing demand is highly under-satisfied, as evidenced by the existing traffic congestion. In theory you could actually satisfy all of it by building a thirty lane triple-decker highway and it would work. Of course, that's still stupid, because what you should do is build a normal highway (e.g. add a lane or two) to absorb some of the demand, and absorb more of it in other ways, as with mass transit or increasing zoning density so that people can live closer to their destination.
  - anonymoushn 6y ago
    Increasing zoning density doesn't help much if it's still illegal to build a grocery store or a coffee shop anywhere near an apartment complex (and the other way around, too)
- iso947 6y ago
  A 1000 line highway would take tens of minutes, maybe upto an hour, to drive to the outside lane, it would have its own interesting traffic problems.
  - TeMPOraL 6y ago
    I can imagine you'd want to split it e.g. into 250 4-lane tracks, with the leftmost track being reserved for people going all the way to the end of the highway, rightmost track for people who're about to exit the highway, and the middle tracks for people traveling to various points along the highway path, sorted left-to-right by distance, descending. Otherwise it would be just one huge mess.
doktorhladnjak 6y ago
This overlooks that roads take up space and other resources. If you build or expand a road, that's something else you can't build or expand (housing, offices, parks, schools, etc.) there. Moreover, who wants to live next to a busy freeway? Noise and air quality aren't great. In the 1000 lane situation, people can get where they want, but where is it that they're going to if the fraction of space is mostly roads? You can see the practical limits of pushing for more, wider roads at scale clearly in Los Angeles. A massive grid of wide freeways. Long commutes. Bad traffic even outside rush hour. Auto dependency. Air pollution. High household transportation costs.

sideshowb 6y ago

Pre 2000s transport planning is a textbook study of optimizing for the wrong thing. Although it failed to reduce congestion you could argue the extra trips contributed to GDP... but that's subject to the same problem... Ultimately what is the correct metric though? Well being? https://www.mdpi.com/2071-1050/12/8/3180/htm# https://www.mdpi.com/2071-1050/12/8/3180/htm#

KingMachiavelli 6y ago

As some others have mentioned, I don't think that induced demand or the failure to prevent congestion are failings of the model itself. A congested 5 lane road still has a higher throughput than a congested 2 lane road. However, the largest problem I see which the article briefly touches on is the failure to even consider building something besides a freeway. A `correct` model should be screaming to build public transport. However, consider the following circumstances: 1. As it is many people are forced to have a car even if public transport can serve their main commute but often public transport is more expensive than the marginal cost of driving a vehicle (i.e gas + upkeep) so they choose to drive unless the congestion is extreme (i.e one of the worst commutes in the US). 2. Even if public transport is pretty decent (commute + groceries), they just happen to already have a car because their previous location did not have public transport. So we are back at #1. Or I don't know if I'll move in a year or two so might as well keep the car. 3. OR now that I have a car , I would probably not want to have to pay for expensive parking (& housing) in an area with public transport plus now I'll have to pay a mechanic a premium to even change the oil. So instead I live further away thus reinforcing the need to keep the car. 4 & etc. I need to travel >50 miles (skiing, hiking), renting is a pain and long trip ride sharing is expensive. Groceries are easier to do with a car especially when buying in bulk (Although, if/when I can get Costco delivered same or 2-day with perishables at <=10% premium, then this is a moot point). Cars are pretty (at least marginally or per mile) cheap in America and we do a very poor job making the alternatives attractive if not impossible. Anyone who has a car seems to drive it even if public transport could be used (again outside of super specific commutes in a few cities). Until we can either make car ownership/use more expensive or greatly increase the practicality of not having a car at all, anticipate having a car and being stuck in traffic at least part of the time.

lotsofpulp 6y ago
Hence drastically raising taxes on fossil fuels. The environmental costs of fossil fuels are nowhere close to being represented in the cost of fuel people pay, therefore we have this massive misallocation of resources. But then society will have to vote for sacrificing luxury today for the benefit of future generations, which typically doesn’t go well.

mehrdadn 6y ago

Some more reading: https://en.wikipedia.org/wiki/Induced_demand https://en.wikipedia.org/wiki/Induced_demand > City planner Jeff Speck has called induced demand "the great intellectual black hole in city planning, the one professional certainty that everyone thoughtful seems to acknowledge, yet almost no one is willing to act upon."

mattmcknight 6y ago
That's bizarre, because I see it as the most overused argument over the past 25 years! People oppose any lane additions with induced demand.

ArkVark 6y ago

Hub and spoke public transport is dead. It relies on huge infrastructure investment and open access. The future is autonomous minibusses with algorithmically-derived live routes, served on a subscription basis by private companies to private individuals. This way people of similar socioeconomic status can rub shoulders with eachother and feel more comfortable, and receive a greater standard of service. It might very well be necessary to modify roads and road rules to facilitate autonomous vehicles - that's the kind of public investment we should be making.

knolax 6y ago
> This way people of similar socioeconomic status can rub shoulders with eachother and feel more comfortable, and receive a greater standard of service. That's a lot of work just so you can avoid being near poor people.
pjc50 6y ago
This ends up unreasonably expensive unless subsidised by loss-making VCs.
- ArkVark 6y ago
  It ends up like an Uber, but cheaper since you have no driver and are sharing the vehicle with other passengers.
  - dmitriid 6y ago
    And Uber is endlessly subsidized by loss-making VCs. Uber has been losing billions of dollars every year.
    - colinmhayes 6y ago
      Uber made money this year if you take uber eats out of the equation.
      - 6y ago

sradman 6y ago

> population and land-use patterns... are two of the most important variables in any TDM [Travel Demand Model] All models are based on assumptions. Revisiting those assumptions should be a continuous process that forms a tight feedback loop, especially given the long timelines and large capital costs involved with civil infrastructure projects. If population and land-use assumptions are the key factors then the important questions should be how these assumptions will be validated and how often. These questions seem to be missing from the article.

aaron695 6y ago

The article actually begrudgingly admits the model works fine. It's nice they are honest for a change, normally they just factoid it away. And concludes it's politics. Not sure if I read the same article as everyone else?

renewiltord 6y ago

These big projects aren't about actually solving problems. They're a combination of public works projects and returning money to your political investors. So you choose the project then construct the justification. Because the true confidence interval is really large, you can go either way. If you're good about it, you can drag the project out with delays but with milestones you can talk about politically. Then by the time the project has been discovered to have been unnecessary you're out of power and it's no longer a problem. And your investors have a good return to invest in the next guy to give them the next project.

sthnblllII 6y ago
I think a lot of Americans are still in the world war 2 generation mindset about the US being corruption-free. The truth is that corruption at every level has gotten steadily worse throughout the last century, but the culture hasn’t yet changed to be vigilant of it, probably because most Americans are very honest themselves.
- renewiltord 6y ago
  I think that's it, honestly. I think this relatively high-trust culture that Americans have actually makes the society pretty efficient and it's much more pleasant to live in. But it has none of the anti-bodies to the kind of cynical corruption that many other countries find endemic. And so when it came here, America had no defence. Because the host is still so healthy, it still doesn't realize it is carrying this parasite. It'll be interesting to see what happens when the host becomes unhealthy.

massysett 6y ago

Ironically this article exposes the fallacy of “induced demand.” Proponents of this mindset, such as the author of this article, claim that more lanes inevitably lead to more traffic. But the article leads off with an example of a massive highway expansion project that is a “boondoggle” because traffic fell and the lanes are empty. I thought that lanes automatically fill up, because induced demand.

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xsmasher 6y ago
Travellers shift from other modes of transit until the "pain levels" even out again; that's independent of the travelers drying up altogether for other reasons though.
nimbleal 6y ago
Surely, unless the claim was that in all cases, everywhere a new road means new levels of traffic to fill it, a single counterexample does nothing to expose a fallacy? I feel like your “inevitably” here is a bit strawman-y

rikroots 6y ago

I met another faulty transport planning algorithm 30 years ago. Background: my first job in the UK Civil Service was as an admin assistant (I did the filing) in the Highways Contracts division, Dept of Transport. My team's job was to let the contracts for developing plans for new/improved national roads across England. The Algorithm: roads cost a lot of money to build; every proposed route had to demonstrate significant value for money through a cost-benefit analysis for each project, considering a number of different detailed options for the new or improved road. One of the main costs was how much money needed to be spent on buying and securing the land, and compensating the owners for loss of business, etc. In cities and towns, this favoured putting bypasses through the poorer parts of the (sub)urban environment. In more rural areas it favoured routing roads through less productive farmland. The least productive land was land that wasn't being farmed or mined. Routes put through these areas would be given an acquisition cost of £0/meter[1] ... Which is why in 1993 the Government settled on developing an improvement scheme for the A303 which put a new double-lane carriageway straight through the middle of Stonehenge. The proposal didn't go down too well. 30 years - and several administrations - later, the Government is still trying to get the proposal through planning[2] [1] - Though in fact highway lengths were still measured in 'chains' and 'links' back in the early 1990s: https://en.wikipedia.org/wiki/Chain_(unit) https://en.wikipedia.org/wiki/Chain_(unit) [2] - Current proposal for the project: https://assets.highwaysengland.co.uk/roads/road-projects/A303+Stonehenge/Environmental+Non+Technical+Summary.pdf https://assets.highwaysengland.co.uk/roads/road-projects/A30...

nicolaskruchten 6y ago

I broadly agree with the article, but one point where it falls short is that it doesn't mention that the 4 stages of the model can be (and sometimes even are!) iterated in various ways to account for the way real people actually behave: modellers in the 21st century aren't quite as naive as all that (and probably the ones in the 50s weren't either but they had less data/computer power). For reference, the four stages go like this: you start with "trip supply and demand" by zone, then inter-zone trips are generated by matching those up, then mode choice is computed per trip based on cost and travel time priors, then assignment to the network which results in actual trips and computed travel times based on route selection and congestion. The travel times can then be fed back into mode-choice and iterated on: people will make the transit-vs-car choice differently based on the relative costs (in time and money and inconvenience) so iterating the last two steps can go a ways towards modelling that equilibrium. Folks can exert some amount of choice around which trips they make (as mentioned in the article) and where they work, based on how easy it is to get there, so feeding the travel costs back into trip-generation can account for some of that, and over a longer horizon, both workers and employers can exert some control over where they live/site their facilities, so all 4 stages can be iterated as well. None of this is perfect, and it's not always done, and the rest of the article's points stand, but I just wanted to say the modelling is not all that primitive :) Edit: I studied this stuff in university 15 years ago with Professor Eric Miller, who wrote this book on how to integrate all this stuff in an iterative way... https://link.springer.com/article/10.1007/s11067-005-2630-5 https://link.springer.com/article/10.1007/s11067-005-2630-5

DoreenMichele 6y ago

The interstate system dates to 1956.[1] So it is part of the set of mental models that haunt the US and continue to poison our built environment. The post-WWII era is the same era that gave birth to the modern suburb and the Baby Boom, giving us the Baby Boomers. Americans have been basically brainwashed into thinking that patterns of development from that era are right and good and so forth and then we put those models on steroids and do more of that same. Our suburbs began as houses of around 1200 sq. ft. Last I saw stats, the average new home in the US was over 2400 sq. ft. (though a recent private conversation with a professional urban planner suggests those figures may finally be dropping). We need an entirely new set of mental models, something I think of as "the butterfly economy" based on a comment I made on HN once.[2] There is a potential path forward, but we aren't going to take it because that would involve listening to a woman and this will not happen. This is a hill our current world is eager to die upon, so we will remain haunted by the ghosts of Christmas past -- prisoners of mental models that served our parents and grandparents extremely well, so they got burned into our collective psyche as the only good way to do anything and never mind that the world has changed and all of that is very much out of date. I'm short of sleep, tired of getting zero respect, underfed (as is the norm late in the month), in a generally bad mood over how my crappy existence remains crappy largely due to sexist BS and no amount of pointing out the sexist BS causes it to really budge. So I think that's all I'm going to say here since I fully expect to get kicked in the teeth for saying anything and I've had quite enough abuse for one life. [1] https://www.fhwa.dot.gov/interstate/interstatemyths.cfm https://www.fhwa.dot.gov/interstate/interstatemyths.cfm [2] https://news.ycombinator.com/item?id=22028732 https://news.ycombinator.com/item?id=22028732

rmrfrmrf 6y ago

Not shocking at all that Vice would frame an algorithm designed to create construction jobs via federal funding as "broken" and "poisonous".

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thehappypm 6y ago

Public transportation should really just be bus-based. Every city that has a large public transit system — worldwide - spends an absolute fortune on trains, track maintenance, overhead lines, operators, and so on. Even shiny European systems are hugely hugely expensive. They often use a wide variety of approaches — Boston for example has about a half dozen completely incompatible rolling stock. Buses can be deployed and scaled cheaply, routes can adapt quickly, dedicated bus lanes can be built with paint and not tunnels. Choke points can use dedicated right-of-way and electric infrastructure can go into tunnels with far less ventilation need. Buses can handle a fallen tree by driving around it. Buses don’t need special tracks to take them to depots. A down bus doesn’t back up the buses behind it. The list goes on and on.

currymj 6y ago
do you have any thoughts on what causes these systems to stick to trains? to me, as a user of public transit, they just seem somehow more pleasant, in a way I can't really make sense of. I strongly dislike riding in buses and try to avoid it, whether part of transit systems, Greyhound/Peter Pan, or even high-end charter buses. maybe if you had electric (no exhaust, quiet) buses with frequent reliable service, dedicated lanes almost everywhere, nice bus stops without hostile architecture, I wouldn't feel such a strong preference, but I'm not sure. I'm wondering whether it's not just that I subconsciously dislike getting jostled around and feeling slightly carsick.
- thehappypm 6y ago
  I think perception is the largest part. The word “bus” conjures up a dirty, homeless-guy horror show to a lot of people, compared to the quiet elegance of a train conductor peacefully snipping your ticket in a leather chair. Second, in many cities, trains actually predate the highways. Third, trains have super high capacity, as do subways and light rail. You need more buses to keep up. However, buses are cheap, and there are things like extra-long articulating buses and double-deckers that can be used on high-volume or long-haul routes. I think buses actually have a practical edge here: instead of trains coming every hour, you could have a big bus come every 10 minutes, which smoothes out load at end stations. And if one breaks down, the other buses can just drive around it. If a subway breaks down in New York, it can cause delays that ripple out to the whole system.

brundolf 6y ago

This kind of complex-system-optimization problem seems ripe for improvement via machine-learning. Cases where 1) precisely modeling the outcome is totally intractable, and 2) you really just need to get "close enough" to get good results. It also helps that this case is predictive in nature (so it's easy to go back and measure accuracy) and has an enormous set of available training data (all traffic happening everywhere across the country). It feels very similar in spirit to that story about Google reducing data center energy use by 40% via ML optimization: https://deepmind.com/blog/article/deepmind-ai-reduces-google-data-centre-cooling-bill-40 https://deepmind.com/blog/article/deepmind-ai-reduces-google... More broadly I've started wondering if there's a huge opportunity to apply software to civil improvement. Everything from detecting patterns of corruption, to aggregating data that can inform voters, to identifying sources of inefficient spending. I don't put much stock in things like digital voting/governance, but in the area of "data crunching and presentation" I think there's a lot that could be done.

nicolaskruchten 6y ago
> an enormous set of available training data (all traffic happening everywhere across the country). I'm not sure this is very helpful to predict traffic patterns over the next 20-30 years in a policy-sensitive way... All the historical data in the world wouldn't have predicted the rise of Uber, the pandemic, the maybe-eventual rise of self-driving cars etc.
- brundolf 6y ago
  True, but it doesn't sound like the approach described in the article factors in extraordinary circumstances like that either
  - nicolaskruchten 6y ago
    The model won't tell you how likely these scenarios are, but one advantage of this class of model over black-box ML function-fitting is that you can do scenario planning. You can do models runs like "what happens if the price of oil shoots way up?" or "what happens if 50% of the cars are taxis?" (e.g. Uber-driven future) or "what happens if transit all of a sudden gains a huge perceived cost?" (e.g. respiratory-virus pandemic) in the third and fourth stages of the model. In the early stages of the model you can look at stuff like "what happens if firms abandon city centers?" or "what happens if 50% of white-collar work is done from home?" etc.