Induced demand is not a useful concept
bensouthwood.co.uk
bensouthwood.co.uk
I did transportation research, and taught it at the masters level, for more than 10 years. His "arguments" against the concept of induced demand are pretty much part of the basic understanding of everyone in the field. There is none of the epiphanies of the author that are not part of a basic transportation planning class.
"Induced demand" is tightly linked with urban sprawl, which the author seems to have just discovered. The critique of induced demand is pretty much centered on the fact that urban sprawl is widely considered as bad, which the author does not seem to even aknowledge. I could write an answer long as a book, but this would be giving this article too much weight.
Do yourself a favor and just ignore this.
I would concede that the wording is not great, but this is unfortunately often the case with concepts that develop over decades.
Isn't this exactly what the author's point #2 ("More and better infrastructure lets us spread out and enjoy more space") was about?
They just take too much space
"More and better infrastructure lets us spread out and enjoy more space" only works to the point where you can still get to the centers of activity in your city within a reasonable time, and past a certain point you either have to bulldoze the center to make space for the vehicles of the suburbanites, or densify
It is insane to me that they decided to write an entire blog post about something like that if they didn't even address this
So honestly I agree, it's a trashy piece
What is there to enjoy with sprawl? Every place ends up being like every other place: (strip) malls, parking lots, stroads, highways, Nature bulldozed, etc.
Everywhere becomes nowhere:
> The Geography of Nowhere: The Rise and Decline of America's Man-Made Landscape is a book written in 1993 by James Howard Kunstler exploring the effects of suburban sprawl, civil planning, and the automobile on American society and is an attempt to discover how and why suburbia has ceased to be a credible human habitat, and what society might do about it.
* https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham'...
You say "His "arguments" against the concept of induced demand are pretty much part of the basic understanding of everyone in the field." That may all be well and true, but it is definitely not the understanding of many laypeople who frequently spout the phrase "induced demand" as some sort of evidence for an "if you don't build it, they won't come" mindset.
That is, I see all the time on the Internet (especially since I'm in Austin, TX, which has notoriously bad traffic, and tons of Austinites are trying to shut down the state-mandated expansion of the major highway through the city), people using an argument of induced demand as to why no more roads should be built.
Thus, you may differ on the exact definition, but I think an article like this is useful for pointing out the benefits of building additional road capacity, even if it does get "filled up".
I also have no problems with "laypeople" not being aware of the research and having only a half-informed opinion. Even experts cannot be familiar with everything. This is actually something I love about HN, that people with general curiosity come to discuss about topics they are not always experts in.
My problem is that, before boldly stating that everyone in the field is wrong, he does not seem to have taken the time to get familiar with what they actually say. But he can write, and _sounds_ informed. I consider this a dangerous combination.
I do not think anyone serious ever said "no more roads should be built". But no one builds roads just for the sake of it: one builds roads, in very broad terms, to the benefit of society and the economy. What transportation planning research is about is pretty much to try to understand (i) what is actually of benefit to society, as far as the transportation infrastructure is concerned, and (ii) how to actually achieve it. And to be honest, no one really agrees on either point.
At its core, the author argues that "induced demand" is strictly false, posits that it's all "latent demand" instead, and then from there effectively ignores the concept of "induced demand" entirely.
Now, for the sake of definitions, "latent demand" is demand that only exists when a given means is made more attractive. "induced demand" is demand that exists, but is using alternatives. In other words, "induced demand" are people using the best option of multiple choices, "latent demand" is people choosing no option because the best option is not worth choosing at all.
When doing things like improving infrastructure, the increase in usage is a mixture of both "latent" _and_ "induced" demand. At what ratio between the two is context dependent.
So, let's go through the examples:
(1) UK highway goes from 3 lanes to 4, sees 10% total increase in volume
The citation does not look at what ratio of that 10% are people that are changing their mode (or time of day) for their transport vs those that are not making the trip entirely. The author argues that the 10% is 100% latent demand, that every single one of those trips would not have happened otherwise. The citation does not provide that evidence, it just says 10%, but does not say why or where that 10% came from. This example does not disprove or prove induced demand.
(2) more subsidized housing would result in more subsidized housing being used
Arguably "living somewhere" is something that 100% of us do, unless we don't, in which case we are talking about a dead person. If we build more subsidized housing, and that means more people can choose to live there instead of in a tent - that's induced demand. This is an example of induced demand......
Let's be more charitable though and say those living in a tent are completely unhoused (and thus represent latent demand). Is there any data that more subsidized housing would not also lead to people switching their non-subsidized apartment for a subsidized one?
Arguably housing is 100% induced demand, you live somewhere and are choosing the best of several options. Being more charitable, again, we are not seeing an example that says anything one way or another about induced demand.
(3) Length of a line for subsidized bread
Let's consider this example a bit differently. Let's say the bread is free, and the line is non-existent. At that point, I would probably go and get some bread. Though, at some point the long will be long enough where I'd just buy some bread instead of waiting for it (an example of induced demand). Alternatively, I might choose to go without bread entirely because I do not want to wait for it, and maybe there is none available to be purchased (this would now be an example of latent demand).
That's the last example, in all cases the examples don't support the hypothesis that induced demand is strictly false. I think the fatal flaw of the article is that it does not go on to address induced demand at all, basically takes the hypothesis as a given. I would expect there to be refutation of the explanations that induced demand is at play. Basically something along the lines of "if this were induced demand at play, then we should see X, but we see Y instead, which fits better with an explanation of 100% latent demand."
> people using an argument of induced demand as to why no more roads should be built.
I suspect people are using induced demand as an example of why some roads should not be built. The reason for expanding many roads is that it will reduce travel time. That reason does not always hold water, specifically induced demand. If all things were taken into account, then perhaps spending 50% of that road expansion money on say better buses - would be more effective for reducing travel times. It depends on context, generally though US civil engineers do not take into account induced demand (AFAIK; my impression is US civil engineers treat traffic as if it were purely 100% a flow of water, a fixed amount that is independent of the piping).
> Thus, you may differ on the exact definition, but I think an article like this is useful for pointing out the benefits of building additional road capacity, even if it does get "filled up".
While that could be very well true in some cases, there could be even greater benefits for committing those resources to alternative means of transport than additional road capacity. It is context dependent. At the same time, when the "benefits" are not as great as claimed, at some point it becomes snake-oil and we are left stuck in a traffic jam.
Obligatory Not Just Bikes video: https://youtu.be/CHZwOAIect4?si=BR9sFwxYDJSAWYLG
Even if you phase it in you risk simply forcing people to move into the city exacerbating existing housing prices. It feels like you need a very very substantial increase in housing prior to increase in taxes. For instance in cities that have excessive single family housing bulldozing houses to build substantial apartments then phasing in taxes.
The alternative is probably pretty ugly because people have a seemingly very high tolerance for bad traffic. They will keep moving to the city and keep driving until driving in the city is beyond untenable.
I think punishing drivers is a bad idea. It'd be much better to provide alternatives to driving that are attractive enough that people choose to use them because it actually benefits them to do so. Not many people are looking for their city to hurt them until they have no choice but to make do with things that are worse and less convenient for them. Give people a better option and they'll flock to it naturally. I've spent enough time in places with amazing public transportation that I know it can be the preferred option for 80-90% of my needs. That's what we should strive for.
I think we have the ability to give people better, less isolated, housing options that many would find preferable to cookie cutter houses in labyrinth-like subdivisions that cut them off from the rest of the city unless they can drive, but those options will have to minimize the downsides of living in close proximity to many others and come with additional benefits that more than make up for what you're asking people to give up.
https://www.usnews.com/news/us/articles/2023-05-08/washingto...
Separately some areas like shoreline have decided to allow upzoning near transit. 4 neighbors got together and sold realizing a 75% premium over home value.
https://www.kiro7.com/news/local/neighbors-selling-homes-as-...
For example charging smokers more for health insurance.
If it isn't hurting them then it isn't incentivizing them to change their behavior, and any tax painful enough to drive wealthier people to change is going to disproportionately impact the poorer people who can least afford it and who are also more likely have the least opportunity/ability to change.
Charging smokers more for health insurance wouldn't be any better if we'd structured our entire society around forcing people to smoke in order to function and while many were still left with no other viable alternatives besides smoking. People generations before we were born allowed the auto industry to shape our cities in ways that made their products essential to our day to day lives and it doesn't do much good to punish people today.
For most people, the entire idea that it's "their decision" to drive cars is questionable at best. Many people would already prefer for things to be different. Give people an alternative solution that meets their needs and actually improves their situation and there'll be no need for flagellation.
I'm not suggesting we get rid of all street parking, but it's currently at absurd levels. It would be great if some of those subsidies went to something else that lessened the need to own a car in the first place.
I mean, the traditional answer is pretty clear. Roads are public transportation infrastructure. Parking cars (and bikes and scooters) is allowed, because cars move the public around. All these other things are not transportation for the public. People think of parking spots along the streets as "landed property", but they're not, they're more like the overhead bins in a bus or plane.
But also, from a practical sense, no one cares about public transportation anymore, so you actually can now park random crap in the street, anytime you'd like?
At least in Michigan, restaurants routinely do the "park a picnic table with a BBQ on the side of the road" thing all the time (see https://www.giffelswebster.com/dining-platforms-and-parklets...) -- many of which still persist since COVID assistance ended.
And residential/commercial construction workers routinely do get to block off street parking for a tablesaw or any other construction usage at job sites all the time.
You don't have to pay to do those other things either. You might not be able to because of safety reasons (e.g. a BBQ in some places) but the "for free" isn't relevant.
It's like thinking that people pay income tax but companies pay employment tax. Companies would happily pay you the employment tax, as they've already budgeted paying that much for you anyway. Thinking this is some free money that doesn't affect people is incorrect.
No you can't. If you try you will find yourself voted out of office and replaced with someone who immediately removes those taxes - and everything else you were doing to make alternatives better.
If you want to make people not drive you need to start with a better option. Start building great transit. Great transit isn't possible without quantity, so build a lot of it. Make it fast and frequent. Once people have a good (not always better, but it needs to be good) we can talk about how to get the stragglers still driving out of their cars. However very few places in the world have this problem and so it isn't worth talking about.
Ideas like this disproportionately affects poor people and minorities. Sure, you've reduced traffic, but now only the Right Kind Of People can afford to drive. Not a great look.
Very clever, you sure got me.
> 4 in 5 citizen lives in an urban area where one could with sufficient investment live without a car.
Most definitely not. Americans living in a typical suburb have no option except to drive or walk for perhaps hours (often with no sidewalks) to get basic necessities. Even within the vast majority of US cities, typically it's a minority of neighborhoods well serviced by walkable amenities and transit, and the rest are still car-dependent.
Again, walking 45+ minutes for basic errands is not a reasonable ask. Bike infrastructure is usually lacking or absent and is forbiddingly dangerous to people who aren't strong and confident bicyclists.
Yes, being able to get to the only grocery store several miles away is a luxury. Driving 45 minutes to work because there's no jobs in walking distance other than fast food is a luxury. Going to the only doctor that takes your insurance/medicaid on the other side of town is a luxury.
You're either not from the US or you're so privileged that you cannot conceive the kind of life anyone less fortunate than you leads. Our entire society is built around the assumption that everyone drives. If you don't, then fuck you, get a car you bum. It's your own fault you're suffering. Get some bootstraps and buy a car already, you're just lazy.
If you are in the US, just try going without a car for a month. You won't last more than three days. Then come back and tell me what a luxury it is.
I lived in SF without a car for 7 months. Getting out of the city was a pain in the neck because the weekend Caltrain schedule is terrible (going from Paris to Brussels is faster than San Francisco to Mountain View), getting groceries was inconvenient because I was in the outer sunset, where it is only residential (it hadn't occurred to me that there wouldn't be a suoermarket withing walking distance when looking for housing), and commuting downtown had a monthly delay because of some car getting stuck trying to go into the tunnel in west portal. All of those things are problems that need solving. I now still live in SF, on the other side of GGP, with a supermarket a block away, multiple restaurants and a direct bus line to downtown with a dedicated bus lane. The difference is night and day. I still use the car once a day, but never use it to commute. Cities can be improved. If you live in a suburb and work on an office park, nothing in this conversation will ever affect you, except maybe a potential future where the most radical changes to the city cause you to park on the outskirts and take transit, or pay a premium to drive in in order to go to some event or night out.
Unless you live in the downtown proper, you must have a car to survive.
I agree that cars are bad and we need public transit, but that is not the reality we are in right now. Today in the real world in most of the country, you're fucked if you don't have access to a car. Which is why we need public transit.
Cars are expensive, so poor people usually rely more on public transit like busses, which get stuck in traffic behind cars. Driving more is positively correlated with higher income.
Lower income people disproportionately suffer the consequences of the current car-centric system like air pollution, noise pollution, traffic violence, etc.
This feels like a totally theoretical idea, or one from a place very different from the US. I think a lot of posters here are from the US where having a car is almost mandatory and you'll only take the bus if you're literally too poor for a car. Most low income people in most US cities can afford cars, it's just a massive burden, but without a car they would have so much less time because transit is bad.
Alternate modes of transportation don't even have to be faster, it just can't be substantially worse. I'd gladly add an extra 10-15 to my travel time if I can spend that trip relaxing in a comfortable and well-maintained train and not have to deal with traffic, other drivers, parking, etc.
People will still want cars, and in many cases still need them, but a huge percentage of our driving could be eliminated as long as public transportation was made the more attractive option.
As you say, better can mean a little slower, but not a lot slower. Creating a better transit system is expensive, but still cheaper than cars.
Overall for society yes, but in most places where transit is widely used, it is quite costly. E.g. a season ticket between Reading and London is 512UKP/mo. For the individual traveler it may not be cheaper especially if they already need to own a car to go to Tesco etc.
That plus a bike made for great urban transportation.
I have a truck I almost never drive (the fuel gauge is broke so I fill it 2x year just to ensure I never run out). Between taxes, insurance, fuel, and maintenance I'm still spending $100/month just to keep it in my driveway - that is about as low as you can possibly get for a car.
That trip it is about 40 miles (plus distance to/from the stations, but lets assume you live next to the station and are going to the other station). At 20mpg, going to/from work every day you are using a bit over $200 of gas per month (In Europe fuel prices are a lot higher than the US, I don't know must how but $600 would not surprise me)
Of course realistic if you are driving that much you are not going to be able to keep a paid off car on the road for very long, plus you have maintenance. Between payments when the car isn't paid off and maintenance you are probably averaging $200/month - for the cheapest car. (you can lease new cars for $900/month).
I'm already at $500/month to drive a car, and I'm assuming the cheapest reasonable prices. Realistically people making that trip every day are likely to have more expensive cars. And of course I used US prices while UK prices would be very different.
Cars are expensive, and so even when you pick a transit trip much more expensive than I think is reasonable cars still come up expensive.
Or perhaps (also?) at least consistent.
While there are trips that can be 'too long', I think what a lot of people hate a lot (maybe even most) is variability. If a trip is (e.g.) 43 minutes for >95% of the time, then they'll probably accept it. But if sometimes it is 30 minutes, sometimes 43, sometimes 57, and everything in between, then it's hard to plan your life around that.
A related behaviour I've observed is how some drivers prefer to be moving very slowly rather than being in stop-and-go traffic, even if both end up getting you to the same destination.
Although, admittedly, waiting on a delayed train or bus in inclement weather can be pretty lousy. Having sheltered bus stops or indoor spaces (like a cafe) near stops/stations can make that experience much more comfortable.
But then, with driving, traffic presents you with similar dilemma, along with the added "fun" of much higher injury/fatality rates, the direct expenses of gas and insurance and maintenance and repairs, and the chances of people pulled over by a cop with a bad attitude.
To my mind, very little is as important as the ability to get up and move when you see fit. Cars actually suck for this without a lot of support and a lot of Americans' hard-earned money being sunk into resources and infrastructure that just sits there the vast majority of the time. I'd rather empty busses and trains I can count on to be there (and be safe) versus my experience with owning my personal vehicle (dangerous and expensive).
Other places I have lived in I need a car, but a small hatchback is fine, and the next time I plan to get a smaller one - cheaper to run, easier to park, better for the environment and the roads.
This is mentioned in the latest NJB video, "More Lanes are (Still) a Bad Thing":
> The difference for induced demand for cars, and induced for other modes of travel, is that cars are a extremely space inefficient. You can absorb a lot more induced travel demand on a subway line, tram line, or bicycle path, than you can in a car lane.
* https://www.youtube.com/watch?v=CHZwOAIect4&t=15m54s
The Oh The Urbanity! channel has a good video on this, "What People Get Wrong About Induced Demand":
* https://www.youtube.com/watch?v=8wlld3Z9wRc
Cars have (AFAICT) the lowest hourly through-put of any transportation mode:
* https://en.wikipedia.org/wiki/Passengers_per_hour_per_direct...
Meanwhile east coasters have roughly the same HOV-less, 2-3 lane highway infra in the suburbs that we had 50 years ago when the population in some areas was 1/2 of what it is today. Worse yet, we also have roughly the same transit infra we did then too.
You can tax cars/roads, you can make trains free, but at the end of the day.. you need to build SOMETHING. If you want your economy to grow as your population grows, you need to grow your infra. It's a sorry state in the NYC metro area because we are not.
You can't just keep slicing up the existing infra pie differently, you need to grow the pie. Otherwise you are just reallocating winners & losers, and unlikely to make the overall situation any better.
Thinking we will simply increase the pain of driving until the existing state of trains is tolerable is idiotic, but I see plenty of this in the alt-transit movement. Make trains great, make them awesome, make me want to take them.. make me regret having to drive when I do!!
If they're not there, they're probably somewhere more sprawly, that uses more energy and cuts more space out of the environment.
If dastardly "newcomers" have to move elsewhere, they chalk that up as a victory for degrowth, as if those people poof out of existence as soon as they leave the metro area.
How do you make cities denser, larger, and more compact without.. building things?
There's a lot of well-intentioned regulations that had the cumulative effect of making it really hard to build things, and people have gotten used to this. Many even feel entitled to randomly stop new construction for whatever reason they feel like, and many planning boards are all too happy to go along with them.
The people who suffer most from not enough new housing, after all, are potential residents, and potential residents can't vote.
Converting 1 out of every 4 or 8 lanes on dense cities to be bus only would decrease the number of cars that can be physically on the road, but increase the throughput of people, as buses do scale much better than single occupancy cars.
But even this is "building" for a very low bar/definition of building. You need to actually create new bus routes, paint lanes, put up new signage, add cameras for enforcement, coordinate with NYPD to ticket, etc.
Even this simple example of "building" is something the city seems paralyzed and unable to accomplish outside of what.. 14th st?
In my experience, governing bodies that use terms like "induced demand" have a high probability on failing to provide those details. But will still want to take the capacity down.
They didn't add a bus, light rail, trolley, or anything. They kept all the parking. But they painted cute little two way bike lanes. It's a regular pedestrian promenade. Surely increases the value of my condo.
Nor did they allocate reasonable pickup/dropoff taxi zones or delivery loading/unloading, so its a giant mess of double parking and people improvising.
Also makes literally zero trips for me faster, and most of them slower. And all the traffic has spilled over onto adjacent streets creating worse traffic.
While it's incredibly hard to believe, it is true. If you look at population statistics for Philadelphia up to the 1980s, it fell to 4/5ths its peak in less than a couple decades.
Driving from river-to-river, or from city-to-suburbs or vice versa was a nightmare, according to everyone older than me. Driving "through" or "to" the center city's impassable traffic grid was hopeless. Then, in 1984, they took advantage of the government buying all the bankrupt railroads and used that property to create a below-ground highway Vine-Street Expressway for river-to-river traffic and connected Penn Railroads Center-city terminal with Reading's system through an underground commuter tunnel and turned Reading's terminal into the Convention Center instead of a giant mess off railroad track interlockings leading into Reading Terminal making traffic even worse. If not for that, I have no doubt it would be 3/5ths the peak population. I could write a 50-page paper on all the things it fixed and I was only 2 when it was all built.
Of course, train tracks are also vacant almost all of the time, but when there is a train, the passengers are packed much closer together than in a typical road vehicle.
He also equates space with comfort but doesn't seem to consider the 2nd-order consequences. More roads, more space on roads, more space between things, and more infrastructure to accommodate cars shifts people from walking and cycling and so on, to cars, because the distances become greater. It's a kind of zero sum game. I wonder if the author would consider THIS demand-shifting to be "induced demand"?
I wish people understood this more. Parallel travel lanes really just create reptile-brained jostling for position, push-pull accordion effect. it's one thing on highways, but I absolutely can't stand it in city traffic. That constant rush to get to the next intersection, the weaving in&out of lanes just to gain a car length, that mindless churn that when there is a gap it needs to be filled. Like being surrounded by mindless automatons in a weird fill-the-next-gap game of life at best, by insecure typeA losers at worst.
Drivers are a lot more calm and considerate when they just chug along in single file. And it doesn't even impact total travel time!
The weird thing is. It is absolutely impossible to explain this to anybody. There's always the immediate reaction, but see more lanes, more lanes is better, more cars in more lanes. Intuition really fails here, it's an emergent property of drivers being 90% id the second they step in a car, and then throwing these dumb beasts in a system that doesn't curb their instincts.
Thanks for sharing, hadn't seen this!
Knowing your bottlenecks is like 80% of performance management whether it's for software engineering or traffic engineering.
For sure, but it the purpose of this discussion, and just looking at the real world.
People are not packets. Traffic is a social phenomenon mostly. It's been a huge mistake to treat it primarily as an engineering problem.
I think there is a legitimate criticism of induced demand that it usually doesn't provide a tradeoff for when you have enough roads. 0 roads in all size cities isn't the answer. At some point a city has enough roads and should focus on mass transit or other transportation. I've never seen an induced demand argument attempt to define this threshold and why.
That's the case most of the time anyway. There are situations where making travel along a road better does improve the situation at first, but it leads to attracting the development of new destinations along that route which can increase the demand for travel on that same road.
For most places the amount of redesign required to fix our terrible traffic infrastructure is going to be a huge problem, but there's hope for new developments and growing cities to avoid these problems and provide amazing public transportation, bike lines, walkable spaces, and better zoning.
If demand were met (globally) then adding a train line (or highway, or stroad) would have a neglible impact on traffic and business development patterns - because everyone can already get to their needs and wants in a timely and economic fashion and therefore has at most casual incentive to use the new infrastructure.
For instance a literal "road to nowhere" may 'induce demand' but only because there is unmet demand elsewhere.
Latent demand and induced demand are distinct:
> The technical distinction between the two terms, which are often used interchangeably, is that latent demand is travel that cannot be realised because of constraints. It is thus "pent-up". Induced demand is demand that has been realised, or "generated", by improvements made to transportation infrastructure. Thus, induced demand generates the traffic that had been "pent-up" as latent demand.[6][7][8][9]
* https://en.wikipedia.org/wiki/Induced_demand#In_transportati...
Though some folks say that it is a distinction without a difference.
The impacts on unsegmented linear street parking are obvious. Dunno why monthly/yearly permits for those aren’t by the (square) foot/metre.
Wider needs more space to get in/out of a spot.
this isn't very useful. all modes of transportation have scaling limits where it becomes cost or space prohibitive to increase capacity. interestingly, trains have many of the same issues as cars. mostly empty trains are not cost efficient, and finding space to store out-of-service rolling stock is a non-trivial problem in transit systems for dense cities. it's not obvious at first, since trains do have a huge space efficiency advantage to begin with, but subterranean space is extremely expensive when you need to build more.
there is also a tradeoff between cost and space use. we don't think of space (in the basic geometric sense) as the main constraint on the capacity of the subway, because there is obviously a lot more room for tunnels into and under manhattan. it's just not economic to build them right away. but you could also build multi-level freeways and underground parking garages with vehicle elevators. it's definitely not economic to do that today, but it might be at some point in the future.
a final observation and bit of a tangent: we build most transportation systems (cars, buses, trains) to have capacity that is only needed for a few hours each day, and often only in one direction. why do we not question more the basic assumption that a large fraction of an urban catchment area's population needs to commute back and forth from many distant residential areas to a single downtown core every day? I'm not just talking about WFH here. why do we not incentive more local clusters of work locations? it seems to me that a lot of the scaling problem would be solved if we worked closer to where we live.
You're really not wrong, but also, it is a real heck of a problem to rein in.
Allow me to digress for a moment and then I'll tie it back: I arrived at the induced demand conclusion, after thinking it was mumbo jumbo for a while, when I realized that human tolerance for misery is the constant value. Humans, in the aggregate, clearly have a tolerance for misery which exceeds that of driving for hours in L.A. traffic. Enough of them individually tolerate it in fact, to keep those traffic arteries clogged for probably up to 5 hours a day on a good day. Build a new lane or route, wait a little while, the traffic scales to keep the commute times roughly the same, because if they got any better, a couple more people would eventually decide it's worth it to go for that great career opportunity that puts them in a car 3 hours a day, or, people who were driving 3 hours a day before but found it trending to 2 would think "I could get that big new-construction house 3 towns further out and my commute would only be back to what it was before the new lanes were added. Cool!"
Anyway, since the equilibrium misery level (which we can't change without mind control) isn't already enough incentive to spur them to come up with a less distant work/home separation, I'm not sure how much success any initiative to 'get people' to work closer to home would have unless it was imposed by a totalitarian state (perhaps as powerful as the Communist Party of China? Though I'm not making any specific comparisons to actual CPC actions because I don't know China well enough). People already want to, all things being equal, but they also will really want the higher-paying job -- or the many-bedroom house for their growing family -- even if it is "too far."
Also, side note: suburban office buildings today are one of the most distressed real estate assets, so it seems that the idea of just providing places for work closer to suburban residential is already not finding enough buy-in from the business owners who would create these jobs.
The things people do when there is more opportunity are good things. That larger house is (to them) a good thing. that job was not better despite more pay because they would have to move - uprooting their family (and spouses job) to take it. This are things your city should strive to enable people to do.
Note too that trains can take the rails well outside of your city limits to be stored. You need to build that track, but you probably should anyway.
Of course where people live in a compromise. I want to have a square mile all to myself at times, while other times I wish I lived across the street from a major Broadway show. Cities could do something to attract me to live in the denser situation with the compromises that means, or they can enable me to live in a sprawling area with the compromises that means.
Eg the "cars are evil" crowd sill say something like "oh they built another lane from the burbs into the city, but traffic is still slow because more people now moved from the city into the burbs and are driving in that lane."
You never hear them say, though "I guess that means there was demand for people to move out to the burbs for greater space/safety/quality of life." So even if dad now gets a longer commute, he's clearly choosing to do that because his family overall is better off. To the extent that building the extra lane enabled this, the world is better off even if eventually that lane itself is as saturated as the existing ones.
I am pretty frustrated with the house, the space and I don't feel any more safe or higher quality of life. I did this only because I could not afford the number of bedrooms I need for surprise triplets in the city I was basically born and raised in. From my anecdata of peers, pretty much everyone who lived in an urban environment for most of their lives would like to stay there but cannot afford it.
I suppose I could see the "family is better off" statement being valid but it is not because of the list you mentioned, it is purely affordability for me. My parents were able to afford a 3 bedroom apartment and I cannot.
I'm not so sure that it's only possible to build affordable 3 bedroom homes _because those burbs have roads_. I agree that it's definitely the best path compared to my options in my locale, but there are other cities/countries where I _could_ afford a 3br in an urban environment and the roads are just as rare there.
If affordability were inherently positively tied to land-use-for-roads, I'd understand the argument. For me though, I think affordability is tied to location-demand and way way more people want to live in the urban environment that I'm priced out of.
In the city, I guess we'd have to walk our bikes to Central Park but also we would struggle to have bike-space in the apartment regardless of size (in the house, they just hang out in the garage) So I wonder if your appreciation of your new lifestyle will change as the kids grow.
Good luck!!!
If you want to attempt to net out these calculations and see who's subsidizing whom, we can try to do that. Complaining about the one form of subsidy that happens to align with your point is unrigorous.
Sure, sometimes - but obviously that doesn't scale ad absurdum. So at some point you need to take a more nuanced position on what the actual latent demand is (as this article discusses), what the actual bottleneck is, and what the alternatives are to solve it.
28 lanes in Texas say otherwise
The author seems to seriously underestimate if not ignore the incredible negative externalizaties of car infrastructure.
The clue that this is the case is that if no new roads are good, then tearing out existing roads must be better. This gets you to a silly place rather quickly. At least an abundance of roads stops at some point.
This is an approachable video describing the mathematics behind such if you're concerned from a theoretical/first principles ground
The "induced demand" being criticized is fake demand, because this hidden subsidy is lowering the true price, and as any economist will tell you, demand goes up when the price goes down.
Sprawl is very expensive to maintain due to the per-capita infrastructure costs; eventually the growth slows and the infrastructure starts requiring maintenance, and the property taxes can't cover it.
Eh, not really. Sure, if people cannot find anywhere to live, building a house in place X might push them towards place X. But if everyone already has somewhere to live, building a house in place X is not going to attract people to place X.
Someone already attracted to place X may hinge their move on housing availability, but you need the attraction first for the houses to matter. Building a bunch of houses on the North Pole isn't really going to compel people to move there.
> expanding the economy of the metro area
To a limited degree, but an insular economy does not have much growth potential. For example, let's say place X has gold. But if you can't get the gold out then you can only trade gold between the local residents – who are probably also in the business of gold. Why are they going to trade for your gold with you when they already can get gold themselves? That leaves little economic opportunity.
But if you build a road, then you can ship the gold off to places where gold isn't locally available. Now you've got people who are keen to trade with you.
Section 1 ceases to make sense if a local frame of reference is chosen rather than a global frame. If you have a country where every city in the country is able to supply 50% of the caloric needs of it's citizens, and then one city is able to satisfy 60% of the calories of it's citizens, you would expect people to want to move to that city until the caloric satisfaction approaches a new equilibrium.
Globally, induced demand is not useful, but for the person who bought 10% more food in a particular city it is very useful.
So the argument that the author is trying to makes is wrong. Induced demand is true, locally. Induced demand is less useful when things are addressed globally.
If a city housed every single homeless person their city, you would expect homeless people from other cities to migrate. In the global sense demand is not induced, but in the local sense it is.
When you make travel to a destination easier more people will want to live and work there. Soon, that capacity will be used up and everything will go back to being congested.
If you told voters: your commute will not get better at all, but we want to spend $1B to enlarge this highway so other people can benefit, no one would ever expand a highway again.
So the article is right, as long as you have the wrong model for how cities work and you have the wrong model for why anyone would build a highway.
The demand to travel is still there, as the author asserts, but it's how we use the space we have to provide it that matters. If you add another lane you induce demand for more cars since there is less useful land to build on for other purposes and you make it harder to get around by other means.
> The demand is not really ‘induced’: it’s more true to say that it was always there – when the roads don’t exist to accommodate it you could call it ‘suppressed demand’.
This has been debunked and rebuked to death.
1. The suppressed (latent would have been a better word for what he's claiming but i digress) demand is not for cars, it's for fast transportation
2. Some people will absolutely take trips they otherwise wouldn't when more throughput is available
3. Leisure driving is absolutely a thing
When I think of "suppressed" demand, I think of economically useful demand that needs to exist. Perhaps that's my own bias on the semantics of these words, but if so that's just another reason why I think "induced" is more accurate-to-reality than "suppressed" or "latent"
Also,
> If we offer more subsidised social housing, more people tend to live in it – would we then say that demand for social housing has been ‘induced’?
Yes, yes I would. The demand is for housing, and only a subset (which I would bet is minor) would prefer social housing over detached housing. However, social housing is much more economically efficient (similar to buses and trains and public transit in general), so of course the excess demand will fill up social housing when it comes available.
Did the author get a proofreader or editor before posting this or is it just an independent blog post?
Flipping cause and effect for expansion of roads is wrong.
Of course. One speaks to the potential demand before something changes, and one speaks to the potential demand converting to actual demand after something changed. We went over this already.
> We don't say more low-income housing created demand for low-income people. We don't say building a school created demand for children.
Of course. More low-income housing does not create demand for low-income people. Building a school does not create demand for children.
And expanding a road doesn't create demand for driving. It merely induces it, hence why we call it induced demand, not created demand.
> Flipping cause and effect for expansion of roads is wrong.
There's really nothing to flip. Whether you use latent demand or induced demand just depends on the point in time you are referring to. In the case of roads, one applies pre-construction, one applies post-construction.
It's not like anyone thinks that if we turn the countryside dirt road that sees little more than the occasional tractor into a multi-lane highway that the cars are magically going to show up in droves. It is well understood that we only expand the roads that actually show strong indication that more use will occur when expanded. Hence latent and, later, induced demand – never created demand.
Are you certain this isn't just your own personal view? Just casually double-checking on the internet, I don't see "economically useful" as part of any definition. It seems to be all about "willingness and ability to pay" for a good or service, as useless as it may be.
Because cars have so many unpriced externalities (smog-forming pollution, oil spills, noise-induced stress, tire microplastic dust, undercompensation for pedestrian deaths, etc), often the demand is not actually "economically useful" in the final analysis.
That's the elephant in the room. Since we apparently won't accept carbon/congestion pricing, then (as a fallback) any rational policymaker should want to suppress car demand. Paradoxically this improves economic efficiency, by helping counteract the perverse Externalization Subsidy.
EDIT: Policymakers can sometimes go too far, of course, or not far enough. Policy requires tuning. That's the downside of using central planning instead of Economist's Own(TM) straight sin tax, but again apparently we won't do that.
There are figures for the negative externalities of cars, they are not hard to find. They don't even come close to the economic activity made possible by cars.
A policymaker that suppresses car demand will kill his city. And we are going to get front row seats to see if I'm right: Manhattan congestion pricing is coming, so we'll find out. I predict it's gone within 3 years.
I also predict the New Jersey roads that go around Manhattan are going to get slammed as people who just need to go through Manhattan to the rest of New York avoid it and head North to go around it. This will add enormous congestion, and the net result will be far worse traffic everywhere except central Manhattan.
But since I assume people in Manhattan also travel I suspect it will be a net negative for everyone.
I don't get how you can be so ignorant that you actually forget public transit even exists. Man, they're missing out, I wish the Paris metro was the norm in any city over 500k
Famously dead cities, London, Paris and Tokyo.
But take a look at a map - how do you get to Brooklyn from New Jersey without going through Manhattan? That's the difference.
Those other cities have vastly different geographies. The congestion is about protecting the city center, but Manhattan traffic is quite different.
And to push this conversation further into antagonism, why should the people of Manhattan prioritize people going from New Yersey to Brooklyn by car? The person doing that trip would prefer it if all of Manhattan were completely flattened and turned into a collection highways and bridges, but people live there. If anything, the current state of NY and it's surroundings is precisely the result of attempting to do precisely that.
In the cities I mentioned you have the same situation. If someone lived in Croydon but needed to get to Wembley or Edmonton, you're not gonna find a highway connecting those two places. But you will find a train that or tube that gets you there, faster than if you'd driven.
That said, NYC needs to get better at thru-running trains across jurisdictions to make metro area crossing journeys easier
we street-park a car here most of the year - if i use the car to visit them the travel time is shortest (20m walk -> 1hr 5m drive)
but i feel very lucky to have a bunch of non-car options - if the weather is nice or i'm off-peak i can ride my bike to NYP in manhattan (8 miles), take my bike on the nj transit train to their stop, and ride the last three miles to them (~2h)
otherwise i can take the subway -> path -> nj transit (~2h 50m, but if schedules were more sensible it could be closer to 2h 20m)
and you might be like "the car is the obvious answer, look at how well you've proven my point!"
but that neglects the time requirement and responsibilities of keeping a car in NYC that i think should be factored into this - either 90m of your time once a week to move it for street parking, or a $65 ticket most of the time. if i'm returning to the city finding a spot can take 25-60 minutes and is often a 15-20m walk from my apartment.
there's a meaningful transaction cost each time the car is used AND in storing the car. and that's with free street parking once you've found a spot, which i don't think nyc should have in the first place!
This will eventually happen, just a matter of time. All cities worth their salt are calming traffic. Manhattan is expensive right now, despite it being ghastly polluted by ice cars, it will be 10 times more when it's actually a nice, calm outside environment. The regional economy will not suffer, it will bloom even more.
This is moot. Yes, people demand fast transportation. Fast transportation in practice means cars. In other words, people demand cars.
You'd almost think they profit from that message somehow.
Luckily for transit enthusiasts, the Kochs have not always been successful, even in sprawling cities with a sizable Republican base. Phoenix, Arizona[1], successfully expanded its light rail system in the face of opposition from the organization’s state branch.
https://www.theguardian.com/us-news/2019/aug/26/koch-activis...
https://grist.org/article/the-koch-brothers-hate-public-tran...
It's can be quite a lot faster to travel through populated areas via train than car. When you have 30k+ people per square mile, cars do not work. Trains work really well.
I'm remorseful we made it such in practice. It didn't used to be that way, and I disagree that it should continue to be that way, for enough reasons that several popular YouTube channels with millions of viewers have already put in the effort to elucidate better than I could.
There are cases where this is true:
https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&d...
When networks are deficient, roads can lead to large benefits:
https://sites.bu.edu/neudc/files/2014/10/paper_243.pdf
As networks reach sufficiency, the impact on economic activity decreases:
https://www.sciencedirect.com/science/article/pii/S0967070X1...
This is not something that can be accurately shoved into an all good or all bad perspective. Whether roads are positive for economic development is a necessarily quantitative question.
>only a subset (which I would bet is minor) would prefer social housing over detached housing.
The author is speaking from a British perspective, and there "social housing" means government-subsidized housing. It is not a form factor and cannot meaningfully be placed in opposition to detached houses.
Since we're on hacker news,
'the design (need) calls for fast transportation. Claiming we need to build to support more cars is enforcing an implementation without actually considering other design alternatives that will satisfy the need'
It's really not for you to decide what is a "useful" trip for people. That leads nowhere good. I mean, how far will you take idea that you decide what's "worth it" for people to do?
> This has been debunked and rebuked to death.
Your premise is not supported by your argument, the opposite in fact. If people want to take a trip, but don't because it's too slow, that is indeed the definition of "suppressed".
> demand is not for cars, it's for fast transportation
Those are currently synonyms. After you have created a new world you can redefine things, but in arguments like these you have to use the current meaning of things.
In every place that I've used public transportation, which is not just in the US, public transport takes twice as long as a car. I even went online to Google Maps and picked random addresses in London - supposedly the public transport capital of the Western World, and the law holds: Cars are twice as fast.
With our current infrastructure, yes, but that's because of how we chose to design things. If we built 10 residential towers within a 7 minute walk of a rapid transit station, and run trains every 3 minutes at peak times, you bet your bottom dollar transit will destroy a car commute for every resident of those towers. I'm thinking of places like say, Daly City and Colma BART, for instance, whose locations would be great car commutes at 2AM, but 5-6 stops on a train beat rush hour car traffic every day -- IF the first and last mile doesn't ruin it!
Now, I'm 100% not saying "everyone ought to be forced to live in high-rises over a train station" -- but I would absolutely bet you that if such residences were built with a variety of human needs in mind (for instance, plenty of them with 3-4 bedrooms for larger families instead of the usual urban mix of 1-2 bedroom units), people who presently drive an hour each way to work "downtown" would be tripping over themselves to buy them because they'd get to work faster and get to browse Insta en route as well.
Instead though, for the most part, such things basically don't exist. For instance, the sites I'm describing in the Bay Area are surrounded by large tracts of SFH. (Or in the case of Colma, 1/4 that, 1/4 car-centric malls, and 1/2 cemeteries. Genius location for a transit station, guys.)
Anyway sorry for being long-winded, just all I'm saying is cars are twice as fast because we dedicate enormously more space and subsidies to them, and we don't make much effort to design any part of our cities or suburbs in a way that any other type of transit could really work. It's a conscious choice we have made, and a dumb one.
> If we built 10 residential towers within a 7 minute walk of a rapid transit station, and run trains every 3 minutes at peak times, you bet your bottom dollar transit will destroy a car commute for every resident of those towers.
If you added a parking lot lage enough for all residents of the tower to have a car (otherwise it's not a fair comparision), then I would take that bet: The car will still be twice as fast (don't forget to include walking time).
Trains are slow because they have to start and stop constantly, you have to walk to them, you have to get on and off. None of that applies to a car: it's point-to-point.
> IF the first and last mile doesn't ruin it!
And it always does...... no one has solved that.
It does though? In a dense city cars have to constantly stop-and-start thanks to treaffic and pedestrian crossings - there's no gurantee of parking space at the other end - if there is, there's a good chance it's not next to your destination.
I live in Zone 3 London, about 5 miles from my workplace. Point-to-point (so not counting finding a parking space), both driving and the train take about 45 minutes. Cycling takes a bit less time, since cars get stuck in traffic and bikes don't.
Wait, are you claiming that cars don't stop at any point in their journey?
Like this isn't even taking into account your distance metric (L0 vs L1 norms) being less efficient than a train has the potential to be, or the 5 minutes it took me to get out of my parking garage before I'd even see a street vs the 1 minute it would take me in the elevator
What? I just pointed out that at the time most people need to drive we have traffic. I assure you, in San Francisco, I’d win the race even with a little walk on both ends.
> don’t forget walking time
Are you implying that downtown offices have ample space for every worker to park next to their desk? Or advocating a Texas-like downtown with a huge parking lot or garage on every urban block. Parking in an urban core is prohibitively expensive for most, since it uses a ton of very expensive real estate.
> trains are slow because…
This is a strange take. Trains are fast because they stop exactly 6 times between Daly City and Montgomery. Cars are slow because they have to go about 5MPH through a massive part of San Francisco every day between 7:30-9:30AM and 3-7PM. (Forgive me if I’m off by an hour for that particular commute, I left a few years ago).
Cars are much faster at 2AM though, or in rural Nebraska.
My point was, someone who lived in a sane development in those places does not need a personal car. That would be a large enough population to support a grocery right there. The city itself is a quick ride away, so you can do non-bulky shopping easily via the train. And for weekend trips or IKEA runs or whatever, imagining a car rental office onsite is easy, and again, MUCH cheaper than the cost of ownership, including paying the cost of storage, via having a more expensive residence - since it takes up so much more square footage per unit to provide parking for each resident. (Also don’t forget things like paying for window repair after every car burglary!)
By the way. I live in the suburbs and drive a car basically 100% of my trips. I’m not disputing that they’re the only option for how most of our country is planned. Just that we chose this and we could have chosen otherwise. And in theory, undeveloped areas could be built differently.
For certain trips like residential cluster A to residential cluster B. Add in a realistic scenario like commuting to work from your residential tower to a warehouse job in a low density light industrial zone and cars will be faster every time. I live in a place with supposedly world class public transportation and it still makes very little sense to take public transportation outside a few scenarios. Most realistic trips you're looking at 2-3 times the travel time you would have by car, even during rush hour.
In a city with excellent public transport, you get a segregation effect - jobs that don't require (many) vehicles (office work, much of consumer retail, certain kinds of light industry) build up in areas with public transport links. Then industries that do require vehicle access (warehousing, heavy industry, builder's merchants, trade buisnesses) build up in areas without public transport links, since they're cheaper than those with access.
At an individual level driving to your office or training to a warehouse might still work or be necessary, but at a population-level it happens less than you'd think.
This seems kind of an odd one to throw in. Leisure driving is fun, but you generally do it on empty country roads, no? Or in general when the roads are clear. Nobody goes to stop-and-go down a congested interstate or suburban stroad for leisure.
They wouldn't be driving for leisure in those geographic locations without roads with low traffic existing. The demand requires a certain low utilization for this cohort.
Also, as someone who lived next to the convention center (and thus i5) in Seattle for ~5 years, there are absolutely people who will drive down i5 for leisure driving. Lots of people racing or otherwise speeding. Hell I would do the same (minus speeding and reckless driving) along 76 and the Schuylkill when I lived on the east coast. Heck some of the biggest opposition in Seattle to tearing down the viaduct (damaged by the nisqually, unlikely to survive another earthquake) was from people who 'would miss the view/drive coming into the city's, and would wax poetic about their literal Sunday drives down such, especially right at sunset.
But I also think this observation misses the degree to which most people are uninterested in raising abstract utility for anonymous strangers. If the new road doesn’t make _my_ life better, it’s a waste.
You see it all the time, idiots, mostly civil engineers, with the intent of removing all roads from the map of earth, claim that adding lanes to 76 will cause some sort of apocolyptic end times scenario. As if Daniel's dreams weren't about Babylon but a stretch of crucial highway transit.
The phrase "induced demand" induces a headache every time. Truly these people seem to think "demand" is something bad. The truth is the lack of development on 76 has caused many Billions of dollars of damage to our region. The best those fat-on-the-government-teet engineers can give us is a 5 billion dollar, 8000 foot extension to a unused 'high speed rail line'. MORONS.
Should we build a railway to connect to the west coast? NO! That would Induce Demand and that's bad! Should we build a road to connect Rome to Constantinople? No! Road are bad! the Silk road was evil!
Demand is good. There is almost endless untapped demand that won't get released into economic dollarydoos because 76 is a parking lot of traffic.
With a double decked 8 lane each way, people could easily work in the city and live in the suburbs. With a double decked 8 lane each way we could have MORE economic integration between the city and suburbs. Imagine the tens of thousands people move easily, to live in Cherry Hill and commute to KoP, or have a second office, these city-slut-mongors are obsessed with making transit, not easy as they claim, but literally so impossible we are all stuck in the shithole. Plus who likes city taxes?
Let us unleash the economic power of Philadelphia by INDUCING GREAT ECONOMIC GROWTH. EMBRACE THE DEMAND! MEET THE DEMAND! SUCCEED THE DEMAND!
Trains also don't induce demand in the middle of the routes the same way because there aren't exits to build more garbage. If you want to talk about building expressways from city to city without exits then you have a more apt comparison.