If there's an aquarium at the end of a busy road, and I'm extremely offended by the sight of fish, no amount of added lanes is going to "induce" me to want to get up on a Saturday and drive to the aquarium.
However, if there's a opera house at the end of a busy road and I love the opera and want to go every weekend, inadequate infrastructure can make the experience driving there painful enough that I'll just stay home, but my desire to go there hasn't changed. I'd still love to see the opera and adding enough new lanes will mean I'm able to go.
If congestion increases after new lanes for traffic are added it's probably because the existing demand to travel down that particular road has been being ignored for too long. As long as you're a fan of allowing people to go to the places they want to visit, then adding new lanes of traffic is a really good idea even when it results in more cars on the road. The goal of the new lanes shouldn't be to reduce the number of cars on the road, it should be to allow more people to get to where they want to be.
I agree entirely that a great public transportation system is a much better solution, but for places that don't have one and aren't going to create one, insisting that induced demand makes expanding roads inappropriate is just... wrong.
Ultimately, if falls on cities to provide people with a way to get to where they want to be and leaving bottlenecks in place makes people miserable and stifles the local economy.
Oh no, we're going going to stifle the local economy for billions of dollars, and all we have to do is take on 10s to 100s of billion of dollars of debt to avoid it...
This is just turning into a hedonistic treadmill of turning more and more of your space into transportation infrastructure by means of debt.
Once you get out of your car, a street with more lanes of traffic is far far less pleasant to be in than a street with less. To use an example from Philadelphia near me, which of these streets would you rather spend time in? Vine Street, with 3 lanes of traffic in each direction and a freeway below in the center median?
https://maps.app.goo.gl/3KqvmfbxLcN8wQtp9
Or the much narrower 17th street, with only two lanes total?
https://maps.app.goo.gl/ozmEtLGfh2hojyVo7
As someone who lived nearby for about 7 years, I know which I'd choose.
There's nothing wrong with big roads designed primarily for cars that bring people into or away from quieter areas designed primarily for people where they can walk around and shop.
There is in cities, because there those two things cannot be so neatly separated.
Some historical context here: Vine Street cuts through Chinatown. Prior to its expansion, there were homes and businesses in the space that's now roadway. They were demolished to make way for the car.
The scars of that are still visible today; if you walk through the neighborhood it's clear that Chinatown north of Vine is struggling compared to its counterpart on the south side, and the two sides feel cut off from one another.
And it makes crossing more dangerous. My commute for years involved crossing Vine, and though I sometimes would bike I had to plan my route very carefully because there were few places where doing so would be at all safe.
People live and work on either side of that street. There are senior homes within a few blocks of it.
Among the many things people consider when buying a house or choosing a new place to rent, is the commute time to wherever they might need to go.
A suburb with an hour commute from the job is low on most people's list. Here comes a new highway, or new highway lanes, and now it's only 30 minutes. Great, let's move there... along with 20,000 other people and within a couple years the commute is back to an hour.
Allowing outdated and inadequate infrastructure to make people miserable and hinder a thriving local economy is a terrible idea. Improving and adapting our roadways to meet the needs of a growing community is exactly what we want cities to do. We shouldn't use induced demand as an excuse to neglect that responsibility, we just have to understand the effect so that we can plan for it.
It's also worth noting that induced demand exists even for public transportation systems. A single rail line can solve the bandwidth problem for a longer time than a new lane on a highway, but if growth continues you'll still end up needing to add new trains and rail lines or add additional modes of mass transportation.
Induced demand is never a reason to leave the problem of bad infrastructure unaddressed, it's just something we have to take into account as we try to improve things.
Adding a passenger rail is in principle not very different from adding a 10-lane corridor. Including the problems of what those people do to enter or leave it, and the fact that it too can become overloaded.
That said, yes, of course the rail is a much better option.
1. the observation that, AFAIK, there are no instances anywhere in the world where adding roads or lanes to roads resulted in over-capacity for the roads
2. your claim that this is because of existing demand that was not previously being met
This would appear to imply that the existing demand - which I'd like to call "implicit demand", because it was not visible via behavior until the roads were expanded - is in fact so large that to meet it would require building a road system of so vast a scope that we clearly would not want it.
Put differently, if building roads merely exposes existing demands, and the 10-100x fold increase in roads over the last, say, century, has not yet met those demands, then we should conclude that it is either impossible to meet those existing demands or will require basically the total destruction of so much land that it will be untenable.
Adding new lanes to the road allows that latent, pent-up demand to be satisfied--the induced/generated demand is the mechanism of that satisfaction.
Usually the solution then is not to optimize for road transportation. After a threshold, it makes sense to switch to a more efficient use of land. Essentially, if you added two more lanes to 101, it's still going to take you as long to get to Palo Alto.
Roads are very good things. But they are very costly land-use-wise. So ideally you have lots of roads as a discovery mechanism and then place high-frequency fast transit along the most well-used. Most of America is in regulatory hell, though, so transit is slow and low-frequency, so the road may actually be net better.
the induced demand argument isn't simply that we should never build transportation infrastrucutre, it's that adding a lane to an existing road is a bad way to meet that demand because the traffic that one lane can carry is insufficient to exceed the demand that one lane will induce. yes, the road expansion will be "successful" in that people will use it. but if it was pitched as a way to improve travel times, reduce congestion, or improve safety, that will probably be a failure.
if you're not going to the opera because the road is too busy, and the added lane releases that unmet demand, the road will still be just as busy as before and you still won't get to the opera. everybody else is doing the same math as you, and deciding that if the road isn't too busy they're going to drive. and so the road is always too busy.
The peak demand for car travel is way beyond the infrastructure which is possible to construct and maintain.
More info:
Customer has on prem services that they do X operations with, we'll say 10,000 daily as an example. They look at the metrics and moving to cloud for that many operations would be cheaper. But very soon after moving to the cloud and an expandable infrastructure, operational costs explode. Suddenly they are not doing this 10k times a day, they are doing it 20 or 30k times a day. Whereas before before kicking off whatever job they were doing they were careful to ensure it was important and cleaning up mistakes in scripts doing while 1=1 loops because it had a measurable impact, after the backpressure disappeared, they'd do this operation without thinking about the costs.
0: https://en.wikipedia.org/wiki/Induced_demand