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“Does induced demand apply to bike lanes?” and other questions

149 points by zck 5y ago

throwawaysea 5y ago
Induced demand as a concept just doesn’t make sense. If demand is “induced” it just means that the supply wasn’t adequate to meet demand. That’s it. It isn’t a large mystery, and there isn’t any logical argument or evidence that greater supply will keep “inducing” demand infinitely. There are a finite number of people and finite minutes in a day, and if they are able to derive value from driving more, then they will do so, but only up to a limit. In return for that driving, they will also gain something for it (the value that motivated them to drive). The phrase “induced demand” is simply a part of the rhetorical war waged by anti car activists. I’m also not sure why we need to create a false dichotomy between roads and bike lanes. I need driving to shuttle between home, work, schools, and other activities in a time efficient way. I also like biking for exercise and leisure, although bike commuting hasn’t been practical for me when I’ve tried it. Have cities considered elevated bike lane networks on pillars built into highway medians or sidewalks, so we don’t have to choose just one or the other? What about cantilevered elevated walk/bikeways? Or perhaps they can have an underground driving network like Chicago does.
- kevingadd 5y ago
  Do you have evidence to support this? The effect of widening highways used to support "induced demand" typically seems to hold up. You may also want to read up on induced demand in more depth, because it's about where the demand is, not about how many people are driving cars.
  - lupire 5y ago
    It's also about altering development patterns (suburbanizating) that spreads stuff out more and forcing everyone to drive more or even buy a car in the first place even if they'd prefer a walkable town.
  - sempron64 5y ago
    I'd like to see a study across all road construction whether excessive induced demand is a guaranteed effect. In all articles related to it I only see examples cherry-picked where induced demand negated the effects of adding lanes. However, it's not clear whether this is universally true, true enough to be a rule of thumb, or something that only occurs in specific situations. Anecdotally, removing toll plazas in favor of plate scanners and adding bridge lanes to the Goethals Bridge in Staten Island, as well as widening the Staten Island Expressway, has significantly reduced traffic delays and improved safety for several years. There _are_ more vehicles using the road but not enough more to significantly negate the improvements. https://www.panynj.gov/port-authority/en/press-room/press-release-archives/2020-press-releases/vehicle-crashes-decline-at-new-goethals-bridge-with-wider-lanes-.html https://www.panynj.gov/port-authority/en/press-room/press-re... To me, the case against improving roads is not nearly as open-and-shut as Strong Towns and similar one-sided policy-pushers make it out to be.
    - kiba 5y ago
      It would seems that removing the toll booths dramatically increases capacity and safety without the need to add additional lanes. Also, more vehicles are using the road, true, but you have to remember that it increases over time.
      - sempron64 5y ago
        How fast does demand grow? Does it ever stop or slow down? I know for a fact that far from every highway and road in America is congested: the majority are not. Even many if not most roads in metropolitan areas are not. So you can’t extrapolate demand increases ad infinitum for the current moment.
    - corin_ 5y ago
      I don't know the data (or this area particularly well generally), but intuitively I would expect induced demand to be seen in the majority of cases of roads being updated for increased capacity. Not because of a necessity that any capacity increase must always cause it, but because the decisions of which roads to expand are made by humans who, with the exception of edge cases (maybe the reason for rebuilding was because of the state of the road and increased capacity was a secondary affect rather than the main motivation; maybe corruption led to a poor choice being made; maybe forward looking expecting future demand to increase years later based on other factors like planned new buildings) wouldn't spend money increase capacity unless road traffic has been increasing and looks like it is't about to start trending in the opposite direction soon enough to make expanding the road a pointless short-sighted exercise. Aka if increasing road capacity wouldn't induce more demand, how likely is it to be in a situation where it's considered worthwhile expanding it?
- kiba 5y ago
  If you expand a road, there will be greater usage because demand soaks up supply. However, cars are big and takes up a lot of space, especially since people regularly drive sedans that seat only one individual with max capacity for four to five people. This requires a lot of space to support cars. Of course, you can continue to expand roads. Problem with that idea is that the roads displace other uses of land such as homes and businesses. Roads increase utility of cars, for sure, but that comes at the expense of everything else.
  - fearfulofview4 5y ago
    Don't forget bankrupting municipalities and states by misallocating untold sums of money toward road construction and maintenance and not investment in human capital: schools, healthcare, and other high-ROI public goods.
  - burlesona 5y ago
    Sedans? Try 5000lb, 7-8 passenger SUVs.
  - acdha 5y ago
    It’s easy for people to forget just how spatially inefficient cars are because we’re so used to 30-40% of city space being dedicated to roads and storage. We saw a dramatic example of this next to the bike path I ride to daycare/work: hundreds of new apartments, restaurants & other retail shops, outdoor public spaces, etc. next to a subway station. This was just part of a retail parking lot which broke 50% usage _maybe_ a couple of times a year. The number of people using the space when up by at least an order of magnitude and it’s a lot more consistent economic activity.
  - thereisnospork 5y ago
    > If you expand a road, there will be greater usage because demand soaks up supply. This can only occur when there is sufficient latent demand, or phrased differently, the supply of roads (and sufficiently fungible transit modes) is so insufficient that that moderate increases in supply do not create a surplus. This lack of surplus (traffic) representing an economic inefficiency which it can only be desirable to reduce[0]. What is stupifying is how 'induced demand' (read: building more roads will cause more people to perform economic activities facilitated by transit) is contorted into an argument against building roads. [0]Until such point that traffic inefficiency is in equilibrium with others. e.g. I can't see Manhattan widening 5th ave anytime soon, but most of America isn't pressed for real estate.
- jochakovsky 5y ago
  Based on your tone, it seems like you are critical of the article, but your critique is actually what the article is addressing. Specifically, "Effect 2" demonstrates a unique property of "induced demand" that doesn't fit into traditional discussions of supply and demand.
- crazygringo 5y ago
  > I’m also not sure why we need to create a false dichotomy between roads and bike lanes. Because there is finite width for existing roads between existing buildings, and so quite literally, adding a bike lane often requires removing a car lane. It's not a false dichotomy at all, it's literally measured in meters. > Have cities considered elevated bike lane networks on pillars... Do you have any idea how astronomically expensive that kind of stuff would be? It's just not even on the table, realistically speaking, for 99.9% of places.
  - CorrectHorseBat 5y ago
    Not disagreeing with you, but elevated bike lanes do exist and they are pretty cool.
    - crazygringo 5y ago
      Oh yeah. No, I've seen what that "0.1%" can look like, and they're so fun to ride too... I wish the kind of money was available to put those all over!
  - stephen_g 5y ago
    We have some of that in my city, alongside a big freeway (see [1]) and yes, it’s ridiculously expensive. It is great though, and one of the only options given the number of very busy intersections this popular route crosses. But in the inner city, it wouldn’t make any sense. Inside the CBD, they’ve been taking out on-street parking to put in separated bike lanes, and that‘s just as good. They completely removed car traffic from a bridge in the middle of the city also to add an extra bus land and a bike lane, and while some drivers were annoyed, it used to drop you in a extremely congested bit of the city so wasn’t very convenient in the car anyway. 1. https://www.tmr.qld.gov.au/projects/Veloway-1-Pacific-Motorway https://www.tmr.qld.gov.au/projects/Veloway-1-Pacific-Motorw...
- lupire 5y ago
  Here's a nice articlr thst explains how induced demand is different from latwnt demand: https://www.strongtowns.org/journal/2021/8/24/does-induced-demand-apply-to-bike-lanes-and-other-questions https://www.strongtowns.org/journal/2021/8/24/does-induced-d...
  - erik_seaberg 5y ago
    The article ought to do more to distinguish these. Latent demand: Driving more often because we can now actually get to places when we used to give up trying. Induced demand: Driving more miles per day because space for the roads pushed each building farther apart over time. Going to larger stores because small nearby stores failed to compete.
- willcipriano 5y ago
  I have yet to receive a convincing answer why induced demand does not similarly apply to/or is not a concern for welfare programs, homeless shelters or public transportation. I find it suspect that this theory is apparently only applied to roads, and largely by people who commute by bike.
  - sofixa 5y ago
    The article literally discusses that in the second part.
    - willcipriano 5y ago
      I said convincing answer. My read is that by the theory of induced demand the best way to eliminate bike deaths is to eliminate bike lanes and therefore people on bikes.
      - crazygringo 5y ago
        The best way to eliminate car deaths is to eliminate cars, too. But obviously we're not doing that either. I'm not clear what you're trying to accomplish by juxtaposing induced demand with transportation fatalities, when the two concepts don't seem to have any special connection.
        willcipriano 5y ago
        > The best way to eliminate car deaths is to eliminate cars, too. But obviously we're not doing that either. As far as I can tell that is exactly the outcome the induced demand folks are hoping for, or something close to it.
        crazygringo 5y ago
        I'm sorry, who are "induced demand folks"? What does that even mean? And I'm unaware of anyone proposing the elimination of cars as serious policy. At most it's limiting vehicles in parts of dense pedestrian city centers. People who are generally "left-leaning" on transportation envision a healthy mix between public transportation, cycling, and cars. They simply want car usage to be balanced with alternatives, rather than cars dominating by default. Virtually everyone recognizes that cars are necessary for a wide variety of uses. They're not going away, so I don't think you need to worry about that.
- occz 5y ago
  Your entire comment leads me to believe that you did not even read the article.
- resoluteteeth 5y ago
  > Induced demand as a concept just doesn’t make sense. If demand is “induced” it just means that the supply wasn’t adequate to meet demand. That’s it. It isn’t a large mystery, and there isn’t any logical argument or evidence that greater supply will keep “inducing” demand infinitely. There are a finite number of people and finite minutes in a day, and if they are able to derive value from driving more, then they will do so, but only up to a limit. In return for that driving, they will also gain something for it (the value that motivated them to drive). The phrase “induced demand” is simply a part of the rhetorical war waged by anti car activists. Right, it's not surprising but highway expansions are often sold as "reducing congestion" rather than the reality of "causing more people to drive more miles with the same resulting level of congestion." If the actual goal of highway expansions is to make it efficient for people to drive more miles/have longer commutes then there isn't an issue with there being "induced demand," but there may be various reasons why this isn't actually a very good goal. Highway expansions do have benefits to people who end up moving further out (more affordable housing), but there may be better ways to achieve the goals of providing housing to more people around urban areas by increasing density, or to help people get around urban areas by transit, etc.
  - tuatoru 5y ago
    > There are a finite number of people and finite minutes in a day, and if they are able to derive value from driving more, then they will do so, but only up to a limit. This is the primary objection I have to self-driving cars. By enabling people to do other things while they are travelling, self-driving cars raise that limit considerably. When self-driving takes off, so will congestion.
    - njarboe 5y ago
      This is very true. Hopefully the Boring company can be successful in reducing tunneling costs by a factor of 10 or 100. Then cities will just have to fined the political will to allow them to be built. Maybe public, self-driving taxies can be made to travel close enough together so that they look like and can be called "trains". Then all the public transport supporters might not try and block them even if the tunnels are open to people's individually owned vehicles also.
- caturopath 5y ago
  > Induced demand as a concept just doesn’t make sense. If demand is “induced” it just means that the supply wasn’t adequate to meet demand Supply and demand aren't fixed -- they meet at an equilibrium price. There are latent trips that are canceled, change modes, or time-shifted to deal with traffic because of the high cost. > The phrase “induced demand” is simply a part of the rhetorical war waged by anti car activists. Induced demand is a standard transportation engineering concept. You might argue that it's been hijacked by the anti-car folks or whatever, but tramsportation engineers and planners who want to build car-heavy transportation systems are aware of and use it. They taught it to me in a very conservative civil engineering department.
- deleted 5y ago
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- tengbretson 5y ago
  Induced demand has never made sense. Does building a hospital create more sick people?
  - khrbrt 5y ago
    It increases the number of people getting treated for their sickness, who otherwise would not be.
    - tengbretson 5y ago
      You are describing latent demand.
  - martyvis 5y ago
    No, but it can make them visible and willing to be treated. If people cant afford private health care or are unwilling to travel long distances or wait for a long time on a public health waiting list, they might just put up with being untreated. This is quite common for things like joint replacement or chronic dental issues.
  - majormajor 5y ago
    If you're only thinking about the already-there population, no. But many hospitals have patients that travel to get there. Building a Mayo Clinic hospital in Arizona results in more sick people traveling there for care than otherwise would have. Seems like there are some natural ways this could cause a loop. Now we hire more doctors and train more new specialists. That burnishes the reputation even more. Now more people want to come! (One thing to note is that it's generally always a localized increase, not an absolute one. The people living in the new suburbs that you built a new shiny road to still would've lived SOMEWHERE in the country. You didn't increase that country's total demand for transit. You just redirected it into "road transit from this particular suburb" from wherever it would've gone in the absence of building that suburb.)
    - thereisnospork 5y ago
      The part I always miss, is how is this a bad thing when it comes to roads? Building 'hospitals'[0] for people to use until there are enough hospitals[0] that people no longer have incentive to flock to the new Mayo Clinic in Arizona seems pretty desirable. [0]Roads
kazinator 5y ago
I think that what will spur the use of bike lines is the surge in electric two-wheeled vehicles: e-bikes and e-scooters and such. Thanks, I suspect, to improved battery tech, those things are everywhere. Bike lanes will not induce much demand if all you have is human-powered cycles. Maybe on sunny days, in flat areas.
Lendal 5y ago
I would love to be able to bike to work. But I can't, even if there were bike lanes. I live in an American suburb, which by design is located far from industrial areas, where jobs are. Too far to bike. There are a few high-density residential buildings in the CBD, but they are only affordable for millionaires. The public transportation here is for show. Two years ago, the highway nearby completed a 5-year widening project. During that time, traffic was so bad I had to check Google Maps every day to find out which route I should use. Now that the project is complete, I never check Google Maps anymore. I just use the highway without even bothering, as the cost to drive on it is now clearly the cheapest. My life is better in the short term, but eventually more homes will be built, traffic will increase, at some point I'll have to go back to checking Google Maps every day, and they'll start another road-widening project. I've lived here long enough to experience this cycle first-hand, and nothing has changed logically that would stop this loop from executing again and again. At some point, I'm sure a physical limit will be reached. Either we run out of space, or run out of money, or something else.
- deleted 5y ago
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- breput 5y ago
  Electric bikes really change the "too far to bike" equation. Depending on your fitness level and the route, you could easily ride 10 miles (or more) and arrive with minimal sweat.
  - abfan1127 5y ago
    I agree about the "too far to bike". my current commute is 30+ miles. It still falls into the "too far" category. I do plan on moving within 10 mi which I'm very interested in the bike. Issues still stand that it limits my ability to run errands during the day. I don't run errands every day, but now I'd have to plan. Another downside is I live in Phoenix where summers are 110degF for 60-70 days. Winter is nice!
    - Lendal 5y ago
Lavery 5y ago
There are two other reasons bike lanes don't have the kind of demand induction properties that roads do: -Bike lanes (and ultimately, bike destinations) have way higher humans-per-square-foot of road / parking lot density than cars lanes. The throttling mechanism on behavior for the car example is ultimately drive time, and new lanes quickly become capacity constrained (first at the interchanges; later at the parking; last in the lanes themselves) in a way that slows ultimate travel back to the indifference equilibrium. The equivalent for bikes tolerates a way higher flow of humans. -Induced demand for cars is in part a function of the fact that you can (up to a point) drive at any speed, meaning that if roads are added that support commuting in from 30, 40, 60 miles away, that can be a doable commute. There is no amount of development that will create a 60 mile bicycle commute. Here, the demand induction mechanism with travel lanes and housing is reversed: you need convenient housing to drive the demand for bike lanes.
- sempron64 5y ago
  The reason bike lanes do not have demand induction effects is because there is inherently low demand. A majority of the population cannot use bicycles for long trips, and even those who can cannot use them for all trips. Bike lanes are ableist and classist. Only healthy citizens with an excess of time and energy are able to use them for trips. The elderly, children, those with heart conditions, asthma, or many other health conditions, and anyone needing to transport anything heavier than their own body cannot use the lane. In most cities this represents a minority of the population. Creating exclusionary space for bicycles is the opposite of progressive policy and efficient urban design.
  - Tijdreiziger 5y ago
    What a weird take. Bike lanes do not take away the possibility for those less able to use a car, they strictly add options. You might as well argue sidewalks are ableist.
    - burrows 5y ago
      > What a weird take. Agreed, like looking at the case inside out. > Bike lanes do not take away the possibility for those less able to use a car, they strictly add options. But, that is true only if the bike lanes are “free to build and maintain”. Otherwise, the city is allocating money toward bike lanes rather than something OP would argue is “less ableist”.
0wis 5y ago
One example : Paris 4 years ago, few bike lanes and very few bikes. Detractors of the newly created ones were arguing about the ressource waste. Today it is one continuous line at rush hour and some lanes are completely jammed. I am not an expert, but what a change. The pandemic may have helped but it is a true transformation. Many people who would have never bike in Paris a few months ago now bike daily to commute. It certainly took more than just laying lanes, planning and choosing the right places to create lanes has certainly a lot to do with it. But once the main places were connected by safe lanes, it began and never stopped. Millenia-old super dense city certainly helps too, nonetheless many thought it would be impossible. Would probably be harder in a less crowded place. First and most recent english article I found about it : https://thewest.com.au/travel/europe/parisian-pedal-power-ng-b881981342z https://thewest.com.au/travel/europe/parisian-pedal-power-ng... Not the most precise, but describes well the feeling. [edit] : typo and spacing
majormajor 5y ago
The only difference here that I think is really meaningful is that bike lanes generally aren't already fully built out and at full capacity. If we didn't believe bike lanes would induce demand for biking we wouldn't say "let's get people out of cars" as one of our major reasons for adding bike lanes. We accept - even hope! - from the start that more bike lanes will cause more biking. It has upsides compared to car commuting. But because we don't have an already saturated, congested network of bike lanes, we aren't going to be hitting the limits of "why didn't adding more parallel bike lanes reduce the amount of congestion?" - the congestion just doesn't exist, and we'd have to have a LOT more biking to make it exist. And if we get to that point, it's a big win! Fears of future bike traffic should not stop us from building bike lanes. Everything else about why "they're different" seems like handwaving.
- danhor 5y ago
  The point of the article is that bikes, by virtue of their limited speed, don't suffer the feedback loop of less density that cars do. The distance you can travel by bike in half an hour is not influenced that much by infrastructure.
  - newsclues 5y ago
    Stop and go traffic is much slower than bike trails with minimal interruptions. Good bike infrastructure can make or break a commute in speed and safety
    - meristohm 5y ago
      My bicycle commute (and walking and running commute, depending on weather and mood) is one of the highlights of my day due in part to minimal waiting for other vehicles.
    - u801e 5y ago
      Separated rail or river trails are definitely a plus for bike commuting. But infrastructure parallel to roads with frequent intersections and mid-block driveways isn't really that much different than riding on the sidewalk (with all the hazards that come with it).
Tade0 5y ago
While I believe the logic in the article is sound, I think it missed the mark on what actually transforms cities in such a way. It's not the cars - they're just tools. It's the insatiable appetite for living space. There's a trend in the city I grew up in(Warsaw, Poland) that started over 20 years ago and continues to this day - people grew tired of living in crammed, Plattenbau apartments, so they moved to smaller towns(in part inspired by their notion of how Americans live) adjacent to big cities where all the jobs were. Additionally at that time interest rates were so high that this was an option for those who couldn't get a mortgage for an apartment. Cars followed, but not everywhere. Places close to railways were an exception, but only up to a point, because over time commuters exhausted any spare capacity there was, so the remainder had to drive and bear the not insignificant costs of that. In the meantime a highway was built, but that didn't help for long. Was Warsaw hollowed-out by this? Hardly. What happened instead is that it started cannibalizing smaller (but still relatively large) cities.
RcouF1uZ4gsC 5y ago
I fail to see why induced demand is a bad thing. Faster CPUs also cause induce demand as then software either does more stuff or does stuff less efficiently. That does not mean the we should stop trying to make more powerful CPUs. Even with a constant amount of congestion, it means that more people are using the roads which means that having the road is optimizing for people’s choices. I see that as a good thing, not a bad thing.
- calt 5y ago
  > I see that as a good thing, not a bad thing. I believe that's exactly the point this article is trying to make. Inducing demand for cycling is ideal.
Ajedi32 5y ago
Interesting argument. > In 1941, your kid might have walked 15 minutes to the neighborhood school. In 2021, you drive your kid 15 minutes to school. Oh, and this isn't your choice: they tore down the old school and replaced it with a parking lot. > In 1961, you might have biked or driven a few blocks to a corner store for milk and eggs. In 2021, you drive 3 miles to Kroger for milk and eggs, and there is no corner store. Has your utility increased? Or are you mostly just consuming more resources? I would argue that utility _has_ increased; It's just that the market has re-organized itself such that the increased utility comes in the form of more flexible locations for houses and businesses rather than in the form of decreased commute times. One grocery store every 5 miles costs far less to maintain than 100 corner stores distributed evenly throughout the city, and you can get more house per dollar buying a house in the suburbs rather than if everyone were competing to buy housing smack-dab in the middle of a city. I think perhaps a stronger version of the author's argument would be to point out that road use is an externality. Building more efficient roads comes at a significant cost, but road users don't pay that cost in a manner proportional to their use of those roads. Therefore the market does not factor in road construction costs when deciding how to organize cities, only costs of the transportation itself like commute times and gas usage. I dislike the term "induced demand" for the same reason the author gave. "Induced demand" is really just "demand"; all economic systems work that way. The only thing different about roads is that our current system of road construction funded primarily by income taxes makes road use an externality.
- sudosysgen 5y ago
  A grocery store every 5 mile costs a ton of fuel to maintain as clients need to drive in. It requires much more roads to be built and bigger ones too. It's not clear at all that it's more efficient when considering the whole picture
- aqme28 5y ago
  > One grocery store every 5 miles costs far less to maintain than 100 corner stores distributed evenly throughout the city. I'm not at all convinced that this is true. It would make sense in a vacuum, but there are a lot of negatives from the road infrastructure necessary for large driving-only grocery stores. Dense cities have lots of smaller grocery stores rather than a few large ones. I'm sure there's a reason for that.
ggm 5y ago
yes, but the fixed and variable parameters to "use" and "density" are different. And luckily, except for outside Amsterdam Centraal and a couple of other places, it doesn't matter: The fixed and variable parameters of the model are far above where we want to be and far above where we would be, if we reduced single occupancy car-type vehicle use. If we include the crazy, semi-fatal Dutch microcar, I think we might get to the worst of both worlds: thousands of people old and young driving microcars like they are in Legoland on a toy road, but the road isn't toy.
notfbi 5y ago
I think this covers a lot of good points and I'm happy to see it, but the final section seems like a just-so. I've wondered if the difference in bike-induced-demand=good;cars=bad follows these lines: - Roads/cars often leads to the phenomena of something like grid-lock. A network might be able to throughput 100 cars a minute when only <=100 cars are trying to get through, but try 101 and it starts dropping: If 120 cars attempt passage at once, congestion actually causes the throughput to drop to like 80 (think of those backward-propagating traffic-wave videos). If 150, throughput drops to 70 etc. - You can add more roads/highways but if it doesn't address certain chokepoints, that throughput will still start descending at some point (though maybe a bit higher now like 110 cars/minute). - Sometimes you can address the chokepoints, but after some expansion the remaining chokepoints are essentially having the buildings and city intersections themselves, at which point you can only address the bottleneck by rebuilding buildings further apart, which leads to a cycle of worsening pedestrian access, local-depopulation, and more cars. - And then finally, maybe bikes are different in that they are small and agile with a congestion-failure-mode of being walked. It's hard or unlikely to get to a bike usage level that would lead you to want to move buildings very far apart to support them. - Or maybe bikes are just simply so small that the preferred distance between buildings anyway (for sun light, privacy) can support most realistic biking numbers (which would be limited by density limits anyways: elevators only practically go so high, commuting biking trips can only be so far). - Ultimately I wish there as a bit more explained here, maybe by someone that designs traffic/city simulations if that's how the best cost/benefits are tested now. It's really confusing that urban planning advocates concentrate on the un-improving car-trip-time/congestion KPIs like it's a dunk when it really seems some throughput-capacity utility metric would be more important.
ummonk 5y ago
Given the cost of housing in major cities, and the relatively lower cost in far away suburbs, doesn’t the argument about development patterns imply that building highways will help with cost of housing in the medium-long term?
- wpm 5y ago
  Not if I can only access that lower cost housing with a car shaped money pit of fuel, insurance, and maintenance. I only live in the city I do because with a car payment, it would have cost more for me to live in the suburbs. In the city I can ditch the car.
TedShiller 5y ago
Induced demand is really interesting, and most people aren't aware of it. It applies to things like traffic, and yes, housing. If building more housing lowered rents, I could finally afford a place in NYC, or LA, or SF. Unfortunately it doesn't work that way. But I wish it did.
alex_young 5y ago
No one moves somewhere because the bike lane is wider.
AbrahamParangi 5y ago
Induced demand is a terrible argument anyway. It's like arguing that capitalism is bad because material wealth induces demand for material things like homes and cars and good dentistry, etc. And like, sure, on some level that's kind of true and you can argue this but it completely misses the point that giving human beings the things they want - safety, privacy, freedom, mobility - is generally considered a good thing and the lack of it is called poverty.
- stephen_g 5y ago
  It’s all about what you want to encourage. Inducing demand by improving roads has few positives, and after a while can cause more congestion than before the road was improved! On the side, it causes more pollution (until most cars are electric), is more dangerous for pedestrians and bikes, is space inefficient, etc. etc. So cities should want to induce demand in other types of transport (trains, busses, bikes, walking) and try not to induce demand for cars.
freen 5y ago
Given that over a long enough timeline and in the aggregate humans are rational and humans also want to minimize commute times, it only makes sense that the average commute time across all substitutes converge. Thus, if you wish to decrease your commute as a driver, the best possible strategy is to advocate for increased alternatives.
choeger 5y ago
More interesting question (for me) in the context of cities: Do apartments induce demand similarly to roads? That is, does building more and more (and smaller and more expensive) apartments actually fuel the housing crisis in big cities?
d--b 5y ago
Obviously, bike lanes don’t alter much LA’s development, but I think Europe’s super bike highways must have an impact on where people choose to live. I’d say induced demand applies to any kind of suitable way of commuting
- PeterisP 5y ago
  "Europe’s super bike highways must have an impact on where people choose to live." What I'm seeing in a city with growing bike infrastructure is the increased attractiveness of city homes which are "mid-distance" from jobs i.e. places which are too far to be walkable but within biking distance - if you have to use a car anyway, then you might as well go a bit further and get a suburban home instead, but biking augments public transportation in allowing a bit larger "dense city" instead of a lot larger suburban sprawl.
forrestthewoods 5y ago
I utterly despise the “induced demand” conversation. Will building more lanes “solve” congestion? No! Will building more lanes allow more people to get to more places? Yes!!! Latency and throughout are two different metrics. Building more road does not necessarily reduce latency. However it does increase throughput. This means more people have more access to economic opportunity; and that’s a good thing.
exogen 5y ago
Even as a cyclist, when I hear of new bike lane construction, my feelings on the matter are "meh" or even negative. I think we should instead just normalize cycling among the cars (mostly by educating drivers, who either get pissed or are too cautious to pass even when they have plenty of room). Bike lanes just create the mindset that bikes should be separate traffic, and screw you over as soon as you need to take a left (now you need to merge into the cars on your left instead of already being between them). I rode my bike across the country and my favorite city for cycling is still Cleveland. Not a whole lot of bike lanes, but wide enough roads and flat terrain. And the only time I was ever struck by a vehicle was when I was riding in a bike lane (because they were trying to turn right).
- Scott_Sanderson 5y ago
  That's an old argument, the "vehicular cyclist." Only 1% of people are brave enough to do this. For bikes to have a significant mode share, it has to be more comfortable than "just mix in with the high speed SUVs." Plenty of examples of high mode share, Copenhagen and Amsterdam above 50%, and they do not ask bicyclists to mix with fast dangerous cars.
  - exogen 5y ago
    Surely not every road or destination is going to have bike lanes, so isn't everyone going to have to mix with traffic eventually anyway? Having them in some places but not others is just confusing for everyone involved.
    - deleted 5y ago
      [deleted]
    - Gwypaas 5y ago
      Watch the bicycle infrastructure get better as he get out into the Amsterdam suburbs. Cycling showdown, Amsterdam vs. Calgary https://youtu.be/M8F5hXqS-Ac https://youtu.be/M8F5hXqS-Ac
    - masklinn 5y ago
harpiaharpyja 5y ago
I'm surprised they didn't mention computing power when introducing induced demand.
locallost 5y ago
I ran into the second effect in a study about traffic I glanced at in a library. It was slightly different, but the result was the same. It went like this: 1) more roads means less space for houses 2) this means people live farther away from where they need to go 3) this means they are more dependent on their cars 4) this means there is inevitably congestion and you need more roads 5) go to 1
LordKano 5y ago
My experience is anecdotal but I have observed that in Pittsburgh, the thing that was accomplished by adding bike lanes was to increase traffic congestion on roads that weren't ruined by the bike lanes.
srg0 5y ago
As a cyclist, I believe that bike lanes do induce demand, but there are some important differences. A single road can attract travels which begin or end far away from the road. So its effect is felt on a larger territory and further away. A road needs only few exits to be connected to other roads. Bike lanes are more like capillary network than arteries. A single bike lane is almost useless, because it can serve only travels which begin and end in a narrow strip around the lane (maybe a block away). Two bike lanes which are not connected will be used much less than two connected lanes. Even a single discontinuity of the network can make bike travel unfeasible. So rather than talking about lanes, we should talk about lane networks and their density. And up until certain density the network won't be used much. Only after reaching that threshold we can talk about effects it may have on city development. Similarly, a car road will not generate induced demand nor attract much traffic if it is missing a bridge across the river. Let say a bike lane attracts traffic if the starting point and the destination are within w/2 from the lane. Let's assume uniform distribution of potential starting and destination points. Then in a city area A, a bike lane of length L will attract only Lw/A potential commutes (within a strip around the lane). There are two important observations to be made: 1) the induced demand is proportional to the length of the network L, 2) parameter w is probably small, likely ~ 200m, so 1 km of a bike lane will have a smaller and more local effect than 1 km of the road. To cover 1 km² of urban area, the well connected network would have to be a grid with the total density of bike lanes ~ 10 km / km².

149 points by zck 5y ago

Induced demand as a concept just doesn’t make sense. If demand is “induced” it just means that the supply wasn’t adequate to meet demand. That’s it. It isn’t a large mystery, and there isn’t any logical argument or evidence that greater supply will keep “inducing” demand infinitely. There are a finite number of people and finite minutes in a day, and if they are able to derive value from driving more, then they will do so, but only up to a limit. In return for that driving, they will also gain something for it (the value that motivated them to drive). The phrase “induced demand” is simply a part of the rhetorical war waged by anti car activists. I’m also not sure why we need to create a false dichotomy between roads and bike lanes. I need driving to shuttle between home, work, schools, and other activities in a time efficient way. I also like biking for exercise and leisure, although bike commuting hasn’t been practical for me when I’ve tried it. Have cities considered elevated bike lane networks on pillars built into highway medians or sidewalks, so we don’t have to choose just one or the other? What about cantilevered elevated walk/bikeways? Or perhaps they can have an underground driving network like Chicago does.

kevingadd 5y ago
Do you have evidence to support this? The effect of widening highways used to support "induced demand" typically seems to hold up. You may also want to read up on induced demand in more depth, because it's about where the demand is, not about how many people are driving cars.
- lupire 5y ago
  It's also about altering development patterns (suburbanizating) that spreads stuff out more and forcing everyone to drive more or even buy a car in the first place even if they'd prefer a walkable town.
- sempron64 5y ago
  I'd like to see a study across all road construction whether excessive induced demand is a guaranteed effect. In all articles related to it I only see examples cherry-picked where induced demand negated the effects of adding lanes. However, it's not clear whether this is universally true, true enough to be a rule of thumb, or something that only occurs in specific situations. Anecdotally, removing toll plazas in favor of plate scanners and adding bridge lanes to the Goethals Bridge in Staten Island, as well as widening the Staten Island Expressway, has significantly reduced traffic delays and improved safety for several years. There _are_ more vehicles using the road but not enough more to significantly negate the improvements. https://www.panynj.gov/port-authority/en/press-room/press-release-archives/2020-press-releases/vehicle-crashes-decline-at-new-goethals-bridge-with-wider-lanes-.html https://www.panynj.gov/port-authority/en/press-room/press-re... To me, the case against improving roads is not nearly as open-and-shut as Strong Towns and similar one-sided policy-pushers make it out to be.
  - kiba 5y ago
    It would seems that removing the toll booths dramatically increases capacity and safety without the need to add additional lanes. Also, more vehicles are using the road, true, but you have to remember that it increases over time.
    - sempron64 5y ago
      How fast does demand grow? Does it ever stop or slow down? I know for a fact that far from every highway and road in America is congested: the majority are not. Even many if not most roads in metropolitan areas are not. So you can’t extrapolate demand increases ad infinitum for the current moment.
  - corin_ 5y ago
    I don't know the data (or this area particularly well generally), but intuitively I would expect induced demand to be seen in the majority of cases of roads being updated for increased capacity. Not because of a necessity that any capacity increase must always cause it, but because the decisions of which roads to expand are made by humans who, with the exception of edge cases (maybe the reason for rebuilding was because of the state of the road and increased capacity was a secondary affect rather than the main motivation; maybe corruption led to a poor choice being made; maybe forward looking expecting future demand to increase years later based on other factors like planned new buildings) wouldn't spend money increase capacity unless road traffic has been increasing and looks like it is't about to start trending in the opposite direction soon enough to make expanding the road a pointless short-sighted exercise. Aka if increasing road capacity wouldn't induce more demand, how likely is it to be in a situation where it's considered worthwhile expanding it?
kiba 5y ago
If you expand a road, there will be greater usage because demand soaks up supply. However, cars are big and takes up a lot of space, especially since people regularly drive sedans that seat only one individual with max capacity for four to five people. This requires a lot of space to support cars. Of course, you can continue to expand roads. Problem with that idea is that the roads displace other uses of land such as homes and businesses. Roads increase utility of cars, for sure, but that comes at the expense of everything else.
- fearfulofview4 5y ago
  Don't forget bankrupting municipalities and states by misallocating untold sums of money toward road construction and maintenance and not investment in human capital: schools, healthcare, and other high-ROI public goods.
- burlesona 5y ago
  Sedans? Try 5000lb, 7-8 passenger SUVs.
- acdha 5y ago
  It’s easy for people to forget just how spatially inefficient cars are because we’re so used to 30-40% of city space being dedicated to roads and storage. We saw a dramatic example of this next to the bike path I ride to daycare/work: hundreds of new apartments, restaurants & other retail shops, outdoor public spaces, etc. next to a subway station. This was just part of a retail parking lot which broke 50% usage _maybe_ a couple of times a year. The number of people using the space when up by at least an order of magnitude and it’s a lot more consistent economic activity.
- thereisnospork 5y ago
  > If you expand a road, there will be greater usage because demand soaks up supply. This can only occur when there is sufficient latent demand, or phrased differently, the supply of roads (and sufficiently fungible transit modes) is so insufficient that that moderate increases in supply do not create a surplus. This lack of surplus (traffic) representing an economic inefficiency which it can only be desirable to reduce[0]. What is stupifying is how 'induced demand' (read: building more roads will cause more people to perform economic activities facilitated by transit) is contorted into an argument against building roads. [0]Until such point that traffic inefficiency is in equilibrium with others. e.g. I can't see Manhattan widening 5th ave anytime soon, but most of America isn't pressed for real estate.
jochakovsky 5y ago
Based on your tone, it seems like you are critical of the article, but your critique is actually what the article is addressing. Specifically, "Effect 2" demonstrates a unique property of "induced demand" that doesn't fit into traditional discussions of supply and demand.
crazygringo 5y ago
> I’m also not sure why we need to create a false dichotomy between roads and bike lanes. Because there is finite width for existing roads between existing buildings, and so quite literally, adding a bike lane often requires removing a car lane. It's not a false dichotomy at all, it's literally measured in meters. > Have cities considered elevated bike lane networks on pillars... Do you have any idea how astronomically expensive that kind of stuff would be? It's just not even on the table, realistically speaking, for 99.9% of places.
- CorrectHorseBat 5y ago
  Not disagreeing with you, but elevated bike lanes do exist and they are pretty cool.
  - crazygringo 5y ago
    Oh yeah. No, I've seen what that "0.1%" can look like, and they're so fun to ride too... I wish the kind of money was available to put those all over!
- stephen_g 5y ago
  We have some of that in my city, alongside a big freeway (see [1]) and yes, it’s ridiculously expensive. It is great though, and one of the only options given the number of very busy intersections this popular route crosses. But in the inner city, it wouldn’t make any sense. Inside the CBD, they’ve been taking out on-street parking to put in separated bike lanes, and that‘s just as good. They completely removed car traffic from a bridge in the middle of the city also to add an extra bus land and a bike lane, and while some drivers were annoyed, it used to drop you in a extremely congested bit of the city so wasn’t very convenient in the car anyway. 1. https://www.tmr.qld.gov.au/projects/Veloway-1-Pacific-Motorway https://www.tmr.qld.gov.au/projects/Veloway-1-Pacific-Motorw...
lupire 5y ago
Here's a nice articlr thst explains how induced demand is different from latwnt demand: https://www.strongtowns.org/journal/2021/8/24/does-induced-demand-apply-to-bike-lanes-and-other-questions https://www.strongtowns.org/journal/2021/8/24/does-induced-d...
- erik_seaberg 5y ago
  The article ought to do more to distinguish these. Latent demand: Driving more often because we can now actually get to places when we used to give up trying. Induced demand: Driving more miles per day because space for the roads pushed each building farther apart over time. Going to larger stores because small nearby stores failed to compete.
willcipriano 5y ago
I have yet to receive a convincing answer why induced demand does not similarly apply to/or is not a concern for welfare programs, homeless shelters or public transportation. I find it suspect that this theory is apparently only applied to roads, and largely by people who commute by bike.
- sofixa 5y ago
  The article literally discusses that in the second part.
  - willcipriano 5y ago
    I said convincing answer. My read is that by the theory of induced demand the best way to eliminate bike deaths is to eliminate bike lanes and therefore people on bikes.
    - crazygringo 5y ago
      The best way to eliminate car deaths is to eliminate cars, too. But obviously we're not doing that either. I'm not clear what you're trying to accomplish by juxtaposing induced demand with transportation fatalities, when the two concepts don't seem to have any special connection.
      - willcipriano 5y ago
        > The best way to eliminate car deaths is to eliminate cars, too. But obviously we're not doing that either. As far as I can tell that is exactly the outcome the induced demand folks are hoping for, or something close to it.
        crazygringo 5y ago
        I'm sorry, who are "induced demand folks"? What does that even mean? And I'm unaware of anyone proposing the elimination of cars as serious policy. At most it's limiting vehicles in parts of dense pedestrian city centers. People who are generally "left-leaning" on transportation envision a healthy mix between public transportation, cycling, and cars. They simply want car usage to be balanced with alternatives, rather than cars dominating by default. Virtually everyone recognizes that cars are necessary for a wide variety of uses. They're not going away, so I don't think you need to worry about that.
occz 5y ago
Your entire comment leads me to believe that you did not even read the article.
resoluteteeth 5y ago
> Induced demand as a concept just doesn’t make sense. If demand is “induced” it just means that the supply wasn’t adequate to meet demand. That’s it. It isn’t a large mystery, and there isn’t any logical argument or evidence that greater supply will keep “inducing” demand infinitely. There are a finite number of people and finite minutes in a day, and if they are able to derive value from driving more, then they will do so, but only up to a limit. In return for that driving, they will also gain something for it (the value that motivated them to drive). The phrase “induced demand” is simply a part of the rhetorical war waged by anti car activists. Right, it's not surprising but highway expansions are often sold as "reducing congestion" rather than the reality of "causing more people to drive more miles with the same resulting level of congestion." If the actual goal of highway expansions is to make it efficient for people to drive more miles/have longer commutes then there isn't an issue with there being "induced demand," but there may be various reasons why this isn't actually a very good goal. Highway expansions do have benefits to people who end up moving further out (more affordable housing), but there may be better ways to achieve the goals of providing housing to more people around urban areas by increasing density, or to help people get around urban areas by transit, etc.
- tuatoru 5y ago
  > There are a finite number of people and finite minutes in a day, and if they are able to derive value from driving more, then they will do so, but only up to a limit. This is the primary objection I have to self-driving cars. By enabling people to do other things while they are travelling, self-driving cars raise that limit considerably. When self-driving takes off, so will congestion.
  - njarboe 5y ago
    This is very true. Hopefully the Boring company can be successful in reducing tunneling costs by a factor of 10 or 100. Then cities will just have to fined the political will to allow them to be built. Maybe public, self-driving taxies can be made to travel close enough together so that they look like and can be called "trains". Then all the public transport supporters might not try and block them even if the tunnels are open to people's individually owned vehicles also.
caturopath 5y ago
> Induced demand as a concept just doesn’t make sense. If demand is “induced” it just means that the supply wasn’t adequate to meet demand Supply and demand aren't fixed -- they meet at an equilibrium price. There are latent trips that are canceled, change modes, or time-shifted to deal with traffic because of the high cost. > The phrase “induced demand” is simply a part of the rhetorical war waged by anti car activists. Induced demand is a standard transportation engineering concept. You might argue that it's been hijacked by the anti-car folks or whatever, but tramsportation engineers and planners who want to build car-heavy transportation systems are aware of and use it. They taught it to me in a very conservative civil engineering department.
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tengbretson 5y ago
Induced demand has never made sense. Does building a hospital create more sick people?
- khrbrt 5y ago
  It increases the number of people getting treated for their sickness, who otherwise would not be.
  - tengbretson 5y ago
    You are describing latent demand.
- martyvis 5y ago
  No, but it can make them visible and willing to be treated. If people cant afford private health care or are unwilling to travel long distances or wait for a long time on a public health waiting list, they might just put up with being untreated. This is quite common for things like joint replacement or chronic dental issues.
- majormajor 5y ago
  If you're only thinking about the already-there population, no. But many hospitals have patients that travel to get there. Building a Mayo Clinic hospital in Arizona results in more sick people traveling there for care than otherwise would have. Seems like there are some natural ways this could cause a loop. Now we hire more doctors and train more new specialists. That burnishes the reputation even more. Now more people want to come! (One thing to note is that it's generally always a localized increase, not an absolute one. The people living in the new suburbs that you built a new shiny road to still would've lived SOMEWHERE in the country. You didn't increase that country's total demand for transit. You just redirected it into "road transit from this particular suburb" from wherever it would've gone in the absence of building that suburb.)
  - thereisnospork 5y ago
    The part I always miss, is how is this a bad thing when it comes to roads? Building 'hospitals'[0] for people to use until there are enough hospitals[0] that people no longer have incentive to flock to the new Mayo Clinic in Arizona seems pretty desirable. [0]Roads

kazinator 5y ago

I think that what will spur the use of bike lines is the surge in electric two-wheeled vehicles: e-bikes and e-scooters and such. Thanks, I suspect, to improved battery tech, those things are everywhere. Bike lanes will not induce much demand if all you have is human-powered cycles. Maybe on sunny days, in flat areas.

Lendal 5y ago

I would love to be able to bike to work. But I can't, even if there were bike lanes. I live in an American suburb, which by design is located far from industrial areas, where jobs are. Too far to bike. There are a few high-density residential buildings in the CBD, but they are only affordable for millionaires. The public transportation here is for show. Two years ago, the highway nearby completed a 5-year widening project. During that time, traffic was so bad I had to check Google Maps every day to find out which route I should use. Now that the project is complete, I never check Google Maps anymore. I just use the highway without even bothering, as the cost to drive on it is now clearly the cheapest. My life is better in the short term, but eventually more homes will be built, traffic will increase, at some point I'll have to go back to checking Google Maps every day, and they'll start another road-widening project. I've lived here long enough to experience this cycle first-hand, and nothing has changed logically that would stop this loop from executing again and again. At some point, I'm sure a physical limit will be reached. Either we run out of space, or run out of money, or something else.

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breput 5y ago
Electric bikes really change the "too far to bike" equation. Depending on your fitness level and the route, you could easily ride 10 miles (or more) and arrive with minimal sweat.
- abfan1127 5y ago
  I agree about the "too far to bike". my current commute is 30+ miles. It still falls into the "too far" category. I do plan on moving within 10 mi which I'm very interested in the bike. Issues still stand that it limits my ability to run errands during the day. I don't run errands every day, but now I'd have to plan. Another downside is I live in Phoenix where summers are 110degF for 60-70 days. Winter is nice!
  - Lendal 5y ago

Lavery 5y ago

There are two other reasons bike lanes don't have the kind of demand induction properties that roads do: -Bike lanes (and ultimately, bike destinations) have way higher humans-per-square-foot of road / parking lot density than cars lanes. The throttling mechanism on behavior for the car example is ultimately drive time, and new lanes quickly become capacity constrained (first at the interchanges; later at the parking; last in the lanes themselves) in a way that slows ultimate travel back to the indifference equilibrium. The equivalent for bikes tolerates a way higher flow of humans. -Induced demand for cars is in part a function of the fact that you can (up to a point) drive at any speed, meaning that if roads are added that support commuting in from 30, 40, 60 miles away, that can be a doable commute. There is no amount of development that will create a 60 mile bicycle commute. Here, the demand induction mechanism with travel lanes and housing is reversed: you need convenient housing to drive the demand for bike lanes.

sempron64 5y ago
The reason bike lanes do not have demand induction effects is because there is inherently low demand. A majority of the population cannot use bicycles for long trips, and even those who can cannot use them for all trips. Bike lanes are ableist and classist. Only healthy citizens with an excess of time and energy are able to use them for trips. The elderly, children, those with heart conditions, asthma, or many other health conditions, and anyone needing to transport anything heavier than their own body cannot use the lane. In most cities this represents a minority of the population. Creating exclusionary space for bicycles is the opposite of progressive policy and efficient urban design.
- Tijdreiziger 5y ago
  What a weird take. Bike lanes do not take away the possibility for those less able to use a car, they strictly add options. You might as well argue sidewalks are ableist.
  - burrows 5y ago
    > What a weird take. Agreed, like looking at the case inside out. > Bike lanes do not take away the possibility for those less able to use a car, they strictly add options. But, that is true only if the bike lanes are “free to build and maintain”. Otherwise, the city is allocating money toward bike lanes rather than something OP would argue is “less ableist”.

0wis 5y ago

One example : Paris 4 years ago, few bike lanes and very few bikes. Detractors of the newly created ones were arguing about the ressource waste. Today it is one continuous line at rush hour and some lanes are completely jammed. I am not an expert, but what a change. The pandemic may have helped but it is a true transformation. Many people who would have never bike in Paris a few months ago now bike daily to commute. It certainly took more than just laying lanes, planning and choosing the right places to create lanes has certainly a lot to do with it. But once the main places were connected by safe lanes, it began and never stopped. Millenia-old super dense city certainly helps too, nonetheless many thought it would be impossible. Would probably be harder in a less crowded place. First and most recent english article I found about it : https://thewest.com.au/travel/europe/parisian-pedal-power-ng-b881981342z https://thewest.com.au/travel/europe/parisian-pedal-power-ng... Not the most precise, but describes well the feeling. [edit] : typo and spacing

majormajor 5y ago

The only difference here that I think is really meaningful is that bike lanes generally aren't already fully built out and at full capacity. If we didn't believe bike lanes would induce demand for biking we wouldn't say "let's get people out of cars" as one of our major reasons for adding bike lanes. We accept - even hope! - from the start that more bike lanes will cause more biking. It has upsides compared to car commuting. But because we don't have an already saturated, congested network of bike lanes, we aren't going to be hitting the limits of "why didn't adding more parallel bike lanes reduce the amount of congestion?" - the congestion just doesn't exist, and we'd have to have a LOT more biking to make it exist. And if we get to that point, it's a big win! Fears of future bike traffic should not stop us from building bike lanes. Everything else about why "they're different" seems like handwaving.

danhor 5y ago
The point of the article is that bikes, by virtue of their limited speed, don't suffer the feedback loop of less density that cars do. The distance you can travel by bike in half an hour is not influenced that much by infrastructure.
- newsclues 5y ago
  Stop and go traffic is much slower than bike trails with minimal interruptions. Good bike infrastructure can make or break a commute in speed and safety
  - meristohm 5y ago
    My bicycle commute (and walking and running commute, depending on weather and mood) is one of the highlights of my day due in part to minimal waiting for other vehicles.
  - u801e 5y ago
    Separated rail or river trails are definitely a plus for bike commuting. But infrastructure parallel to roads with frequent intersections and mid-block driveways isn't really that much different than riding on the sidewalk (with all the hazards that come with it).

Tade0 5y ago

While I believe the logic in the article is sound, I think it missed the mark on what actually transforms cities in such a way. It's not the cars - they're just tools. It's the insatiable appetite for living space. There's a trend in the city I grew up in(Warsaw, Poland) that started over 20 years ago and continues to this day - people grew tired of living in crammed, Plattenbau apartments, so they moved to smaller towns(in part inspired by their notion of how Americans live) adjacent to big cities where all the jobs were. Additionally at that time interest rates were so high that this was an option for those who couldn't get a mortgage for an apartment. Cars followed, but not everywhere. Places close to railways were an exception, but only up to a point, because over time commuters exhausted any spare capacity there was, so the remainder had to drive and bear the not insignificant costs of that. In the meantime a highway was built, but that didn't help for long. Was Warsaw hollowed-out by this? Hardly. What happened instead is that it started cannibalizing smaller (but still relatively large) cities.

RcouF1uZ4gsC 5y ago

I fail to see why induced demand is a bad thing. Faster CPUs also cause induce demand as then software either does more stuff or does stuff less efficiently. That does not mean the we should stop trying to make more powerful CPUs. Even with a constant amount of congestion, it means that more people are using the roads which means that having the road is optimizing for people’s choices. I see that as a good thing, not a bad thing.

calt 5y ago
> I see that as a good thing, not a bad thing. I believe that's exactly the point this article is trying to make. Inducing demand for cycling is ideal.

Ajedi32 5y ago

Interesting argument. > In 1941, your kid might have walked 15 minutes to the neighborhood school. In 2021, you drive your kid 15 minutes to school. Oh, and this isn't your choice: they tore down the old school and replaced it with a parking lot. > In 1961, you might have biked or driven a few blocks to a corner store for milk and eggs. In 2021, you drive 3 miles to Kroger for milk and eggs, and there is no corner store. Has your utility increased? Or are you mostly just consuming more resources? I would argue that utility _has_ increased; It's just that the market has re-organized itself such that the increased utility comes in the form of more flexible locations for houses and businesses rather than in the form of decreased commute times. One grocery store every 5 miles costs far less to maintain than 100 corner stores distributed evenly throughout the city, and you can get more house per dollar buying a house in the suburbs rather than if everyone were competing to buy housing smack-dab in the middle of a city. I think perhaps a stronger version of the author's argument would be to point out that road use is an externality. Building more efficient roads comes at a significant cost, but road users don't pay that cost in a manner proportional to their use of those roads. Therefore the market does not factor in road construction costs when deciding how to organize cities, only costs of the transportation itself like commute times and gas usage. I dislike the term "induced demand" for the same reason the author gave. "Induced demand" is really just "demand"; all economic systems work that way. The only thing different about roads is that our current system of road construction funded primarily by income taxes makes road use an externality.

sudosysgen 5y ago
A grocery store every 5 mile costs a ton of fuel to maintain as clients need to drive in. It requires much more roads to be built and bigger ones too. It's not clear at all that it's more efficient when considering the whole picture
aqme28 5y ago
> One grocery store every 5 miles costs far less to maintain than 100 corner stores distributed evenly throughout the city. I'm not at all convinced that this is true. It would make sense in a vacuum, but there are a lot of negatives from the road infrastructure necessary for large driving-only grocery stores. Dense cities have lots of smaller grocery stores rather than a few large ones. I'm sure there's a reason for that.

ggm 5y ago

yes, but the fixed and variable parameters to "use" and "density" are different. And luckily, except for outside Amsterdam Centraal and a couple of other places, it doesn't matter: The fixed and variable parameters of the model are far above where we want to be and far above where we would be, if we reduced single occupancy car-type vehicle use. If we include the crazy, semi-fatal Dutch microcar, I think we might get to the worst of both worlds: thousands of people old and young driving microcars like they are in Legoland on a toy road, but the road isn't toy.

notfbi 5y ago

I think this covers a lot of good points and I'm happy to see it, but the final section seems like a just-so. I've wondered if the difference in bike-induced-demand=good;cars=bad follows these lines: - Roads/cars often leads to the phenomena of something like grid-lock. A network might be able to throughput 100 cars a minute when only <=100 cars are trying to get through, but try 101 and it starts dropping: If 120 cars attempt passage at once, congestion actually causes the throughput to drop to like 80 (think of those backward-propagating traffic-wave videos). If 150, throughput drops to 70 etc. - You can add more roads/highways but if it doesn't address certain chokepoints, that throughput will still start descending at some point (though maybe a bit higher now like 110 cars/minute). - Sometimes you can address the chokepoints, but after some expansion the remaining chokepoints are essentially having the buildings and city intersections themselves, at which point you can only address the bottleneck by rebuilding buildings further apart, which leads to a cycle of worsening pedestrian access, local-depopulation, and more cars. - And then finally, maybe bikes are different in that they are small and agile with a congestion-failure-mode of being walked. It's hard or unlikely to get to a bike usage level that would lead you to want to move buildings very far apart to support them. - Or maybe bikes are just simply so small that the preferred distance between buildings anyway (for sun light, privacy) can support most realistic biking numbers (which would be limited by density limits anyways: elevators only practically go so high, commuting biking trips can only be so far). - Ultimately I wish there as a bit more explained here, maybe by someone that designs traffic/city simulations if that's how the best cost/benefits are tested now. It's really confusing that urban planning advocates concentrate on the un-improving car-trip-time/congestion KPIs like it's a dunk when it really seems some throughput-capacity utility metric would be more important.

ummonk 5y ago

Given the cost of housing in major cities, and the relatively lower cost in far away suburbs, doesn’t the argument about development patterns imply that building highways will help with cost of housing in the medium-long term?

wpm 5y ago
Not if I can only access that lower cost housing with a car shaped money pit of fuel, insurance, and maintenance. I only live in the city I do because with a car payment, it would have cost more for me to live in the suburbs. In the city I can ditch the car.

TedShiller 5y ago

Induced demand is really interesting, and most people aren't aware of it. It applies to things like traffic, and yes, housing. If building more housing lowered rents, I could finally afford a place in NYC, or LA, or SF. Unfortunately it doesn't work that way. But I wish it did.

alex_young 5y ago

No one moves somewhere because the bike lane is wider.

AbrahamParangi 5y ago

Induced demand is a terrible argument anyway. It's like arguing that capitalism is bad because material wealth induces demand for material things like homes and cars and good dentistry, etc. And like, sure, on some level that's kind of true and you can argue this but it completely misses the point that giving human beings the things they want - safety, privacy, freedom, mobility - is generally considered a good thing and the lack of it is called poverty.

stephen_g 5y ago
It’s all about what you want to encourage. Inducing demand by improving roads has few positives, and after a while can cause more congestion than before the road was improved! On the side, it causes more pollution (until most cars are electric), is more dangerous for pedestrians and bikes, is space inefficient, etc. etc. So cities should want to induce demand in other types of transport (trains, busses, bikes, walking) and try not to induce demand for cars.

freen 5y ago

Given that over a long enough timeline and in the aggregate humans are rational and humans also want to minimize commute times, it only makes sense that the average commute time across all substitutes converge. Thus, if you wish to decrease your commute as a driver, the best possible strategy is to advocate for increased alternatives.

choeger 5y ago

More interesting question (for me) in the context of cities: Do apartments induce demand similarly to roads? That is, does building more and more (and smaller and more expensive) apartments actually fuel the housing crisis in big cities?

d--b 5y ago

Obviously, bike lanes don’t alter much LA’s development, but I think Europe’s super bike highways must have an impact on where people choose to live. I’d say induced demand applies to any kind of suitable way of commuting

PeterisP 5y ago
"Europe’s super bike highways must have an impact on where people choose to live." What I'm seeing in a city with growing bike infrastructure is the increased attractiveness of city homes which are "mid-distance" from jobs i.e. places which are too far to be walkable but within biking distance - if you have to use a car anyway, then you might as well go a bit further and get a suburban home instead, but biking augments public transportation in allowing a bit larger "dense city" instead of a lot larger suburban sprawl.

forrestthewoods 5y ago

I utterly despise the “induced demand” conversation. Will building more lanes “solve” congestion? No! Will building more lanes allow more people to get to more places? Yes!!! Latency and throughout are two different metrics. Building more road does not necessarily reduce latency. However it does increase throughput. This means more people have more access to economic opportunity; and that’s a good thing.

exogen 5y ago

Even as a cyclist, when I hear of new bike lane construction, my feelings on the matter are "meh" or even negative. I think we should instead just normalize cycling among the cars (mostly by educating drivers, who either get pissed or are too cautious to pass even when they have plenty of room). Bike lanes just create the mindset that bikes should be separate traffic, and screw you over as soon as you need to take a left (now you need to merge into the cars on your left instead of already being between them). I rode my bike across the country and my favorite city for cycling is still Cleveland. Not a whole lot of bike lanes, but wide enough roads and flat terrain. And the only time I was ever struck by a vehicle was when I was riding in a bike lane (because they were trying to turn right).

Scott_Sanderson 5y ago
That's an old argument, the "vehicular cyclist." Only 1% of people are brave enough to do this. For bikes to have a significant mode share, it has to be more comfortable than "just mix in with the high speed SUVs." Plenty of examples of high mode share, Copenhagen and Amsterdam above 50%, and they do not ask bicyclists to mix with fast dangerous cars.
- exogen 5y ago
  Surely not every road or destination is going to have bike lanes, so isn't everyone going to have to mix with traffic eventually anyway? Having them in some places but not others is just confusing for everyone involved.
  - deleted 5y ago
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  - Gwypaas 5y ago
    Watch the bicycle infrastructure get better as he get out into the Amsterdam suburbs. Cycling showdown, Amsterdam vs. Calgary https://youtu.be/M8F5hXqS-Ac https://youtu.be/M8F5hXqS-Ac
  - masklinn 5y ago

harpiaharpyja 5y ago

I'm surprised they didn't mention computing power when introducing induced demand.

locallost 5y ago

I ran into the second effect in a study about traffic I glanced at in a library. It was slightly different, but the result was the same. It went like this: 1) more roads means less space for houses 2) this means people live farther away from where they need to go 3) this means they are more dependent on their cars 4) this means there is inevitably congestion and you need more roads 5) go to 1

LordKano 5y ago

My experience is anecdotal but I have observed that in Pittsburgh, the thing that was accomplished by adding bike lanes was to increase traffic congestion on roads that weren't ruined by the bike lanes.

srg0 5y ago

As a cyclist, I believe that bike lanes do induce demand, but there are some important differences. A single road can attract travels which begin or end far away from the road. So its effect is felt on a larger territory and further away. A road needs only few exits to be connected to other roads. Bike lanes are more like capillary network than arteries. A single bike lane is almost useless, because it can serve only travels which begin and end in a narrow strip around the lane (maybe a block away). Two bike lanes which are not connected will be used much less than two connected lanes. Even a single discontinuity of the network can make bike travel unfeasible. So rather than talking about lanes, we should talk about lane networks and their density. And up until certain density the network won't be used much. Only after reaching that threshold we can talk about effects it may have on city development. Similarly, a car road will not generate induced demand nor attract much traffic if it is missing a bridge across the river. Let say a bike lane attracts traffic if the starting point and the destination are within w/2 from the lane. Let's assume uniform distribution of potential starting and destination points. Then in a city area A, a bike lane of length L will attract only Lw/A potential commutes (within a strip around the lane). There are two important observations to be made: 1) the induced demand is proportional to the length of the network L, 2) parameter w is probably small, likely ~ 200m, so 1 km of a bike lane will have a smaller and more local effect than 1 km of the road. To cover 1 km² of urban area, the well connected network would have to be a grid with the total density of bike lanes ~ 10 km / km².