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Maybe induced demand has always happened, in the sense of demand increasing when the product is more available. But it's plenty common for the amount that deman

by tgb 10y ago

Maybe induced demand has always happened, in the sense of demand increasing when the product is more available. But it's plenty common for the amount that demand increases to be less than the amount of extra capacity available. Furthermore, is induced demand that bad? If you double the capacity and it again gets filled to the point of gridlock, well then at least twice as many people are now able to be in gridlock, which they apparently prefer to the alternatives.

mnw21cam 10y ago
The example of when induced demand is bad is when it causes increased pollution. In many parts of the world, there is a deliberate movement towards avoiding building too many roads, in order to decrease road use and therefore pollution levels. However, a car sitting in traffic will produce much more pollution per mile than one travelling at 70mph on a clear road, so the thinking behind this may be flawed.
skybrian 10y ago
It's possible to change the incentives. If the roads are free they fill up until gridlock makes them more painful than the alternatives. If you charge money then the expense becomes part of the cost/benefit calculation. It favors car pooling, rich people (who don't care about the price) and other people who urgently need to get somewhere during rush hour (who can pay the price that one time). You can also just do car pool lanes, which has some similar benefits.
audleman 10y ago
> Furthermore, is induced demand that bad? It's good in cases where you can eventually meet that demand. Say induced demand for broadband leading to more fiber optic cables being laid down. However there isn't enough space in cities to ever meet demand. What needs to happen is a shift away from the single-car culture in America and towards mass transit.
jdmichal 10y ago
To be fair, for traffic, it's not necessarily the number of cars that's increasing. If everyone doubles the number of miles they drive, that will have a roughly equivalent effect. Car-miles is really the metric to watch here.

by tgb 10y ago

mnw21cam 10y ago

The example of when induced demand is bad is when it causes increased pollution. In many parts of the world, there is a deliberate movement towards avoiding building too many roads, in order to decrease road use and therefore pollution levels. However, a car sitting in traffic will produce much more pollution per mile than one travelling at 70mph on a clear road, so the thinking behind this may be flawed.

skybrian 10y ago

It's possible to change the incentives. If the roads are free they fill up until gridlock makes them more painful than the alternatives. If you charge money then the expense becomes part of the cost/benefit calculation. It favors car pooling, rich people (who don't care about the price) and other people who urgently need to get somewhere during rush hour (who can pay the price that one time). You can also just do car pool lanes, which has some similar benefits.

audleman 10y ago

> Furthermore, is induced demand that bad? It's good in cases where you can eventually meet that demand. Say induced demand for broadband leading to more fiber optic cables being laid down. However there isn't enough space in cities to ever meet demand. What needs to happen is a shift away from the single-car culture in America and towards mass transit.

jdmichal 10y ago

To be fair, for traffic, it's not necessarily the number of cars that's increasing. If everyone doubles the number of miles they drive, that will have a roughly equivalent effect. Car-miles is really the metric to watch here.