[aftoprokrustes]

I usually try to be respectful, but here I have to say it: this article is junk.

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.

[hef19898]

Why study something if your first principle thinking allows you to write a brilliant blog post about the most utter basics in the field you don't want to study? The former is work and school, the latter, sometimes, gets you on the HN front page.

[user_7832]

Is this a variation of Cunningham's Hypothesis?

[throw0101c]

> Cunningham is credited with the idea: "The best way to get the right answer on the Internet is not to ask a question; it's to post the wrong answer."[17]

* https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham'...

[sapiogram]

> 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 acknowledge.

Isn't this exactly what the author's point #2 ("More and better infrastructure lets us spread out and enjoy more space") was about?

[aftoprokrustes]

This actually the opposite: he sees it as a positive, which might be sensible on a first look. But there are various problems with it, which completely counterbalance the initial benefits, and which he does not aknowledge. For instance - traffic will tend to grow until congestion negates the initial decrease in generalized cost. For instance, someone living 15 min from downtown might decide to move out in the suburbs due to the low cost of travel: 25 minutea to town is an acceptable tradeoff for the increase in housing quality. But after 10 or 15 years, downtown ends up being 60 minutes away: the household ends up being worst off than if they had stayed downtown. - car need space also when they do not move. If more people go somewhere by car, you meed more parking spaces. Parking space is dead and depressing, and replaced dense accessible neighborhoods, in particular in the USA - transport in general, but in particular car, has negative externalities (negative effects experienced by persons different from the ones benefiting from it). Air pollution or increased travel time to cross the urban area are examples

[throw0101c]

> Isn't this exactly what the author's point #2 ("More and better infrastructure lets us spread out and enjoy more space") was about?

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/The_Geography_of_Nowhere

[sebstefan]

It misses the core point of the people spouting "induced demand", which is that if you were to satisfy the demand for cars, there won't be a city to drive to or to park in at the end

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

[pixl97]

Not only too much space, but an insanely huge amount of money that is spent by future generations via debt. If you happen to lose the popularity contest as a city/state you now have a trillion dollars of crumbling infrastructure demanding ever higher taxation on those that remain.

[throwanem]

Since you're in the field, I'll ask: do you know a good 101-level treatment of the subject? Looking for broad rather than deep, something that gives a good overview and directions for further study. Thanks!

[gensym]

I'm not in the field, but I highly recommend Tom Vanderbilt's Traffic. Not a textbook, but an excellent one (and I've had people in the field speak highly of it to me).

[hn_throwaway_99]

I completely disagree. Not from a "you are wrong, he is right" perspective, but from the perspective that you're basically arguing that his opinion is not valid.

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".

[aftoprokrustes]

My main problem is not someone disagreeing with the consensus in the field. I actually love when someone sheds a new light on something everyone agrees on.

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.

[ravetcofx]

Do you have honest arguments for why TDOT should continue with the expansion? I haven't seen any that are coherent.

[pixl97]

We can make Austin into Houston with a 26 lane highway. We can see that huge highway solved traffic over there.

[bigDinosaur]

There's nothing more tiresome than someone from the states arguing that actually, what you need is more or wider roads. Go ahead and build them, it's thankfully not my tax money (and few places are as bad as the US when it comes to basically exclusively funding roads).

[seadan83]

The arguments are so vacuous against induced demand that the author is left with just opinion. I'm making a strong statement there, but I think I can defend it.

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.

[marcosdumay]

Yeah, the article is clearly aimed at people that insist on estimating the value of transportation as zero or negative. To the point where they get to conclusions like that providing houses with enough space for people to live is bad.

[Tiktaalik]

Agreed. The author is an idiot.