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

The only difference here that I think is really meaningful is that bike lanes generally aren&#x27;t already fully built out and at full capacity.<p>If we didn&#x27;t believe bike lanes would induce demand for biking we wouldn&#x27;t say &quot;let&#x27;s get people out of cars&quot; 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.<p>But because we don&#x27;t have an already saturated, congested network of bike lanes, we aren&#x27;t going to be hitting the limits of &quot;why didn&#x27;t adding more parallel bike lanes reduce the amount of congestion?&quot; - the congestion just doesn&#x27;t exist, and we&#x27;d have to have a LOT more biking to make it exist. And if we get to that point, it&#x27;s a big win! Fears of future bike traffic should not stop us from building bike lanes.<p>Everything else about why &quot;they&#x27;re different&quot; seems like handwaving.

There are two other reasons bike lanes don&#x27;t have the kind of demand induction properties that roads do:<p>-Bike lanes (and ultimately, bike destinations) have way higher humans-per-square-foot of road &#x2F; 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.<p>-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.

One example : Paris<p>4 years ago, few bike lanes and very few bikes. Detractors of the newly created ones were arguing about the ressource waste.<p>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.<p>Millenia-old super dense city certainly helps too, nonetheless many thought it would be impossible. Would probably be harder in a less crowded place.<p>First and most recent english article I found about it : <a href="https:&#x2F;&#x2F;thewest.com.au&#x2F;travel&#x2F;europe&#x2F;parisian-pedal-power-ng-b881981342z" rel="nofollow">https:&#x2F;&#x2F;thewest.com.au&#x2F;travel&#x2F;europe&#x2F;parisian-pedal-power-ng...</a> Not the most precise, but describes well the feeling.<p>[edit] : typo and spacing

Interesting argument.<p>&gt; 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&#x27;t your choice: they tore down the old school and replaced it with a parking lot.<p>&gt; 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?<p>I would argue that utility _has_ increased; It&#x27;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.<p>I think perhaps a stronger version of the author&#x27;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&#x27;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.<p>I dislike the term &quot;induced demand&quot; for the same reason the author gave. &quot;Induced demand&quot; is really just &quot;demand&quot;; 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.

I would love to be able to bike to work. But I can&#x27;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.<p>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&#x27;ll have to go back to checking Google Maps every day, and they&#x27;ll start another road-widening project.<p>I&#x27;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&#x27;m sure a physical limit will be reached. Either we run out of space, or run out of money, or something else.

As a cyclist, I believe that bike lanes do induce demand, but there are some important differences.<p>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.<p>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.<p>So rather than talking about lanes, we should talk about lane networks and their density. And up until certain density the network won&#x27;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.<p>Let say a bike lane attracts traffic if the starting point and the destination are within w&#x2F;2 from the lane. Let&#x27;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&#x2F;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 &#x2F; km².

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.<p>It&#x27;s not the cars - they&#x27;re just tools. It&#x27;s the insatiable appetite for living space.<p>There&#x27;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&#x27;t get a mortgage for an apartment.<p>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&#x27;t help for long.<p>Was Warsaw hollowed-out by this? Hardly. What happened instead is that it started cannibalizing smaller (but still relatively large) cities.

I utterly despise the “induced demand” conversation.<p>Will building more lanes “solve” congestion? No! Will building more lanes allow more people to get to more places? Yes!!!<p>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.

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.<p>Bike lanes will not induce much demand if all you have is human-powered cycles. Maybe on sunny days, in flat areas.

Even as a cyclist, when I hear of new bike lane construction, my feelings on the matter are &quot;meh&quot; or even negative. I think we should instead just normalize cycling among the cars (mostly by educating drivers, who either get pissed or are <i>too</i> cautious to pass even when they have plenty of room). Bike lanes just create the mindset that bikes <i>should</i> 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).<p>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).

I think this covers a lot of good points and I&#x27;m happy to see it, but the final section seems like a just-so. I&#x27;ve wondered if the difference in bike-induced-demand=good;cars=bad follows these lines:<p>- Roads&#x2F;cars often leads to the phenomena of something like grid-lock. A network might be able to throughput 100 cars a minute when only &lt;=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.<p>- You can add more roads&#x2F;highways but if it doesn&#x27;t address certain chokepoints, that throughput will still start descending at some point (though maybe a bit higher now like 110 cars&#x2F;minute).<p>- 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.<p>- And then finally, maybe bikes are different in that they are small and agile with a congestion-failure-mode of being walked. It&#x27;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.<p>- 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).<p>- Ultimately I wish there as a bit more explained here, maybe by someone that designs traffic&#x2F;city simulations if that&#x27;s how the best cost&#x2F;benefits are tested now. It&#x27;s really confusing that urban planning advocates concentrate on the un-improving car-trip-time&#x2F;congestion KPIs like it&#x27;s a dunk when it really seems some throughput-capacity utility metric would be more important.

Induced demand is really interesting, and most people aren&#x27;t aware of it.<p>It applies to things like traffic, and yes, housing.<p>If building more housing lowered rents, I could finally afford a place in NYC, or LA, or SF. Unfortunately it doesn&#x27;t work that way. But I wish it did.

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:<p>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

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.<p>Thus, if you wish to decrease your commute as a driver, the best possible strategy is to advocate for increased alternatives.

I&#x27;m surprised they didn&#x27;t mention computing power when introducing induced demand.

More interesting question (for me) in the context of cities: Do <i>apartments</i> 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?

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?

yes, but the fixed and variable parameters to &quot;use&quot; and &quot;density&quot; are different.<p>And luckily, except for outside Amsterdam Centraal and a couple of other places, it doesn&#x27;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.<p>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&#x27;t toy.

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&#x27;t ruined by the bike lanes.

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.<p>I’d say induced demand applies to any kind of suitable way of commuting

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.<p>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.<p>I see that as a good thing, not a bad thing.

No one moves somewhere because the bike lane is wider.

Induced demand is a terrible argument anyway. It&#x27;s like arguing that capitalism is bad because material wealth induces demand for material things like homes and cars and good dentistry, etc.<p>And like, sure, on some level that&#x27;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.

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.<p>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&#x2F;bikeways? Or perhaps they can have an underground driving network like Chicago does.