induced demand is often (intentionally?) misunderstood as demand being literally insatiable (and by extension, "why bother?"), but really, we're just severly underserving the market, and there are very limited price signals we can rely on to understand the cost and value of a road foot-second (or meter-second).

people want more fast, affordable, on-demand, point-to-point private transportation. "induced demand" tells us we're woefully under-providing that demand. we're very far from the desired equilibrium point in nearly every metro area. elon seems to understand that better than a pithy quip might indicate.

along with mixed-use-as-default along transportation corridors, i would prefer more underground trains, dedicated busways, and small personal transport infrastructure (for electric bikes, scooters, etc.) in our cities (particularly in LA), but every effort, including the boring company's, that addresses that overwhelming demand helps.

On paper, when everything is just objects floating in gaseous infinite space, this makes sense. Once you begin to realize that a car takes space, this all falls apart. You can make the 405 100 miles wide to fit everyone across, but you'd loose the entire county in the process.

The fact of the matter is that it's absurd to transport people in a dense environment 25'x10' apart, one at a time, all going back and forth to the same exact two places five days a week for 40+ years. Trains let you fit way more people in a given area, people who are already heading the same direction, and therefor offer more space for a city to be a city rather than a place for infrastructure.

Until we get to a point where people are able to move easily with high capacity transit, it's irresponsible to waste precious political will to build with the intention of providing low capacity transport for those who can afford a $30k+ car.

> "...realize that a car takes space, this all falls apart."

that's accounted for in the foot-second metric. by a (very) rough calculation, we'd only need to double road foot-seconds to alleviate most congestion. that's very expensive, since most of these roads would have to go underground or be elevated, but not impossible (elon is trying to do just that for teslas).

i'm not advocating we double our roads, however. i'm just refuting the pithy notion that it's impossible to meet the supposedly insatiable demand implied by "induced demand" arguments.

but yes, let's build way more public transit and smaller personal transport networks (along with taller, mixed-use buildings)! it's definitely more efficient and can be less expensive and stressful.

Aand this is exactly why going 3D (using boring tunnels) instead of 2D is the solution.

My take is that road access is severely underpriced.

If you had to pay for road access, you could easily set the price to where demand meets supply, and all roads would have well flowing traffic 24/7.

But of course "induced demand" happens when the price is $0. The same would occur for bread, phones or pianos at that price point.

Roads do have a price, and it does increase with demand. What is the worth of 10 minutes of your time?

The problem is that you don't pay for the slowdown you cause to everyone else. You're offloading that cost, so you keep choosing to use the road well beyond the point where traffic should be increasing.

To make up for that, we can charge people at the entrance point. But charging people time is basically impossible, so money is used instead.

Therefore more roads => more cars => same trip times. I could see that people would make decisions to take jobs where they travel by car, or choose to live further away etc. with more tunnels. That could be a good thing or bad, but yes the demand will increase, because people will find new reasons to get about if there is more road to do it on. Let alone business use of roads.

Do you not see how you're arguing in favor of his/her point?

I think you've missed the point, going by your second paragraph.

How capacity is provisioned from A to B influences how people choose to move and, over the long term, build homes/workplaces.

Induced demand does not suggest that supply is less than demand - it implies that demand is "flexible" to meet any supply conditions. There is overwhelming evidence of this at work over 50 years and across continents.

As a consequence, the argument is not "why bother?" but rather - "build it in a way that scales". For urban areas, private transport doesn't scale well.

> "Induced demand does not suggest that supply is less than demand - it implies that demand is "flexible" to meet any supply conditions."

that's the exact interpretation i'm refuting.

of course supply is less than demand. that's because the price of using roads is (perceived to be) zero, but the cost of construction on the supply side is high (and increasing, relative to inflation). it's impossible to meet the demand for free when costs are high.

my point is that this mispricing is a political and cultural choice, not an economic one explained by "induced demand". by using an economic concept for a non-economic market, we fall prey to misinterpreting and misadvocating.

we need to make the price of private transport much more transparent (e.g., real-time pricing) and rein in costs (land prices, legal/regulatory costs) so that we can make better choices in allocating our precious and limited resources (toward more mass transit for example).

(real-time pricing should also be progressive so that roads aren't just for rich people.)

If you believe that car travel must be innately evil, then induced demand is a problem with building more roads. More roads mean more people using them to do something they want to do. These tunnels will be toll roads, so if you just up the tolls you can have them not get jammed up. You then have a real idea of how much a tunnel can make and you can get people to invest in building more of them.

Individual point-to-point transport systems are great. We just need to find a way to reduce the bad externalities of cars (pollution, traffic deaths, non-walkable cities/town, traffic congestion, taking up surface space). Elon Musk is working on three of these with Tesla and the Boring Company.

> More roads mean more people using them to do something they want to do.

I'd argue that a lot of people don't want to drive a car, they want to get to their destination. Where options other than driving are available, then they weigh cost/convenience to make their decision.

My view isn't that cars travel is innately evil, or that building roads is always terrible - but that so much more money is spent on building more roads than on public transit options.

For some reason we ignore the last 60+ years of evidence to show that building more roads doesn't lead to reduced traffic. It's simply not possible to build out roads fast enough to beat the rise in traffic.

If you build public transit options that get people between locations they want to travel, ensure that it's run on time, clean, and affordable - then people who already drive will evaluate that cost/convenience function for themselves and decide that public transport is actually better. This results in much reduced road traffic.

The bad externalities of cars are numerous and extend well beyond those things you list, but primarily they create an astoundingly expensive barrier to being part of society and not someone who's left behind.

There aren't enough tunnels in the world to dig your way out of traffic problems. The more roads you make the more traffic you get.

Toll roads just increase the already staggering cost of owning a car, marginalizing even more people.

What about not doing that and instead investing in alternatives?

A lot of this stuff, 'ride sharing', self driving cars, boring company tunnels, and electric flopters seems not like a way to solve societies transportation/congestion issues but to solve it for the small percentage of well to do people.

He has said that he doesn't believe in induced demand: https://twitter.com/elonmusk/status/1211076829395738626?s=20

I think he's woefully disconnected from the non-rich person's life, then. He can already afford to buy however much space he wants.

>If the transport system exceeds public travel needs, there will be very little traffic.

Sure. But... it would take an enormous amount of development to make this happen, because so many people are going to want more space if they can have it with still a <1hr commute. So more sprawl, leading to more pressure on the new network, lather, rinse, repeat...

For all the talk of walkable neighborhoods, if you gave people the choice of a 30min walk-and-subway commute in a 5-story condo building vs a 30min new-car-tunnel point to point commute with a 2000sqft house on a private parcel of land, you're going to have a lot (not everyone, but a lot) of people picking the latter.

Best case it's going to, for a long time, until we reach steady state, still just be a repeat of the "build roads, watch sprawl" cycle of the last century, just with potential to build even more roads by being able to continually go deeper (but is this that much easier than vertical overpasses and such?).

> potential to build even more roads by being able to continually go deeper (but is this that much easier than vertical overpasses and such?)

Isn't it easier to persuade local residents to support a tunnel under their area than an above-ground structure in their area?

This is like not believing in climate change.

He also wants to sell more cars. Not less.

Induced demand = the product is actually being used. The hoary old cliché that says, "Building roads just increases congestion," is nothing more than an exercise in measuring the wrong thing.

Market demand, induced and otherwise, is a good thing, if the externalities are also addressed. That's basically Musk's whole business model.

Infrastructure operates differently from a good or service where you have a multitude of often interchangeable selections.

The easy availability of roads leads to more people driving since it's the more effective option, which in turn leads to more traffic. Eventually the system reaches equilibrium where it's busy enough that other alternatives are more desirable.

Time and time again predictions of apocalyptic traffic doom have failed to manifest when roads are removed. The traffic just goes away largely because the traffic was an artifact of the roads being there in the first place.

People are highly adaptable. They take the path of least resistance. If that path is a road, they take it. If you make the road bigger, it reduces resistance and becomes busier.

I know of some areas that would disagree with you: it is possible to out build demand, most rural areas have done it. I have driving 4 lane highways on a nice weekday where I could see for miles in either direction and there wasn't even one other car!

The only problem is cost. For a city to out build unmet demand they would need to get to add several dozen layers of road, one on top of another (that is bridges over bridges for 12 layers). Nobody would seriously propose building such a thing. If we had it the mobility of the city would allow people to accomplish more things in the city than they can today.

So where are we on this particular rendition of the Laffer curve? Are we already fortunate enough to be at "peak road," right here and now? That seems unlikely, but I suppose it's possible. Or would it be best to either remove more lanes, or add new ones?

Would traffic flow become infinitely fast if we removed them all?

Conversely, would it become infinitely slow if we paved every square inch of land in sight?

It's almost as if such simplistic models are worse than useless, huh.

> It's almost as if such simplistic models are worse than useless, huh.

I'd say that it's more like taking models to extremes is useless.

If your doctor says that you're consuming too much salt it is increasing your risk of a range of diseases, you don't turn around and say "But salt is necessary for the function of life, I can't just cut it out entirely!". The answer, as with most things - is somewhere in between.

With our current set of transport options - a mix of transport options are going to be optimal. The specific mix is going to depend entirely on the area and traffic patterns.