> Notice that this is true of anything that relieves the highway congestion in any way whatsoever.
Is that true if we charge an appropriate price for road use? Isn't that what we do to manage availability of every other scarce resource to ensure it is being used optimally?
If you increase the price of using the road at the busiest times then eventually you will arrive at a price that maintains the optimum flow rate. You may need to adjust the price occasionally to track shifts in inflation and population, it has equity issues, and (like most sustainable solutions) it is politically difficult. But I don't understand what would cause it to stop working. In the places it has been implemented (e.g. Singapore, London, Stockholm) it is generally unpopular at first and then extremely popular after a year or so. And administering it should become cheaper as technology improves which may make it feasible for smaller cities as well.
> If the population was stable, and you built a road which is sufficient now, it'll probably stay sufficient as long as the population remains stable, because who is building enough new housing to move the needle on traffic in a city that isn't growing?
Even in metro areas that have stable populations, heavily subsidizing transportation infrastructure (whether transit or highways) between the city and the suburbs often has the effect of slowly shifting the current metro population outward to those suburbs. By subsidizing suburban commuters you are making living in the suburbs more attractive than it would be otherwise. As you make it more attractive, more people who currently live in the city will rationally choose to move to the suburbs.
I'm not saying it's a bad idea to build more lanes, just that on it's own it is not a sustainable approach. As long as rent/land prices are largely set by the market and roadways are free or heavily subsidized then it's not surprising that people take advantage of that and you end up with a shortage of road space.
Is that true if we charge an appropriate price for road use? Isn't that what we do to manage availability of every other scarce resource to ensure it is being used optimally?
If you increase the price of using the road at the busiest times then eventually you will arrive at a price that maintains the optimum flow rate. You may need to adjust the price occasionally to track shifts in inflation and population, it has equity issues, and (like most sustainable solutions) it is politically difficult. But I don't understand what would cause it to stop working. In the places it has been implemented (e.g. Singapore, London, Stockholm) it is generally unpopular at first and then extremely popular after a year or so. And administering it should become cheaper as technology improves which may make it feasible for smaller cities as well.
> If the population was stable, and you built a road which is sufficient now, it'll probably stay sufficient as long as the population remains stable, because who is building enough new housing to move the needle on traffic in a city that isn't growing?
Even in metro areas that have stable populations, heavily subsidizing transportation infrastructure (whether transit or highways) between the city and the suburbs often has the effect of slowly shifting the current metro population outward to those suburbs. By subsidizing suburban commuters you are making living in the suburbs more attractive than it would be otherwise. As you make it more attractive, more people who currently live in the city will rationally choose to move to the suburbs.
I'm not saying it's a bad idea to build more lanes, just that on it's own it is not a sustainable approach. As long as rent/land prices are largely set by the market and roadways are free or heavily subsidized then it's not surprising that people take advantage of that and you end up with a shortage of road space.
(I agree with your comments on zoning.)