People are very much influenced by what the available and expedient modes of transit are between destinations they would like to travel. Many people might want to go enjoy some Hollywood night life on a Friday evening but decide not too because traffic congestion from where they live into that region is not worth it. If freeways and surface roads leading into Hollywood were expanded to decrease travel time, and parking added to reduce traffic costs and searching time, more people might decide to make the trip, because there are abundant points of interest there.

Speaking of limits, what about the limits in land space? Most freeways and arterial roads in Los Angeles are expanded to their limits, and the only way to increase road capacity would be to destroy homes and businesses. This would be expensive both in the costs of expansion but also in the costs to society and the economy by taking land with other already existing valuable uses and turning it over to moving cars. On the other hand expansion to rail could vastly increase the capacity to move people along a particular route with considerably less land use space then automobile infrastructure or in the case of subways no surface land space.

The West Side in Los Angeles is one of the most heavily car trafficked regions in the country, with the 10 and 405 freeways slowing to speeds below in-line skaters at peak hours (I know because I have witnessed skaters on the 10 freeway with my own eyes, while I was riding the freeway on my bicycle at about twice the speed of traffic flow). To get the capacity of people through that region who come to work, or to play at the coast, we simply do not have the land available to alleviate that much traffic with more lane expansion schemes. This why we need to reprioritize government subsides that we currently shovel into the failing automobile system into viable alternatives. People don’t train to Santa Monica because one doesn’t exist yet, it’s just been talk for decades. People don’t take the bus because it is stuck in the same mess as the cars, and with poor frequency and connecting transfer times.

For these reasons most people in LA stick to using the car as a first and often only choice of travel. I love cycling, but not everyone is physically able or dedicated enough to cross the streets of L.A. on a bike. We need a balanced transit system for all modes of travel, and right now it is very lopsided in favor of moving cars. I don’t buy the argument that we need to expand lanes on freeways and roads, we’ve done quite enough of that already with marginal progress at best and very little room to do anymore in many regions.

If it’s such a “good” hypothesis, would not you suppose that you would see it applied to other things as well?

The question is wether or not it’s a bad thing - more demand does not necessarily imply (in the long run) less congestion but it does imply more consumer surplus. Unfortunately, more volume also means more external costs due to increased travel time unreliability, environmental damage and (law of numbers) more unsafety. Given the state of our planet and the contribution of the US (and China) to that state, you don’t have to be a greeny weenie to question wether expanding freeway capacity is a good idea.

Think man

Thanks for the good feedback. You raise some good points.

As a preface, let me say that I can only address induced demand as its proponents define it.

Usually and historically – notwithstanding a few boondoggles like Alaska’s infamous Bridge to Nowhere – transportation infrastructure construction is a response to existing demand. Roads are built to connect two or more places that already exist. The demand to travel between these places already exists, but the existing infrastructure is not sufficient. People already go to these places, and when we improve the way in which people make these trips, everyone benefits. When we upgrade from a four-lane road with numerous traffic lights and unlimited access points to a even a four-lane limited access freeway, drivers benefit from, among other things, reduced travel times and the increased fuel efficiency that comes with uninterrupted operation at highway speeds.

As an example, consider the Dwight D. Eisenhower National System of Interstate and Defense Highways, which turned 60 this year. Ike identified a need to transport massive amounts of troops and materiel from one end of the country to another other in the event of a Soviet invasion. When Ike examined the existing highways, he found them wanting, and commissioned the Interstate Highway System in order to better meet the need.

Ultimately – and unfortunately – many of the issues about which Judd, Lewis, and I are outraged are long-run problems, like failing to expand transportation infrastructure at even roughly the same rate as population growth, much less economic growth. This is why we take such a hard line against the intellectually stagnant, burger-flipping NIMBYists and legislative buffoons who block the major improvements in transportation infrastructure this country needs. The point to which I will always return is that mass transit needs to be at least as convenient or cost-effective for the traveler as driving. Mass transit needs to be a choice made by rational individuals, not an compulsion thrust upon us by vocal lobbyists and heavy-handed bureaucrats.

However, in the long run you can take into account the development that these roads cause. This is what I always assumed this concept referred to (although I could be wrong, I never really studied it and only talked about it in passing).

If you build a highway through an area, that will attract development that would not have been built in the area otherwise. If you assume that it doesn’t bring any new development to the metro area from elsewhere (i.e. I won’t move to New York from Texas because a new road is built through Westchester), than this development would have been at the expense of denser development near existing highways. Because these highways are already congested, and assuming there are viable public transit options in the area, the people housed in this new development would be more likely to take public transit.

For this group of people, it’s not like they’re not being served by this lack of a highway in a lower density area… They would have moved near the highway if it existed and this new development was concentrated there, and would move towards the old highway and take public transit in if the highway didn’t exist.

I also thought induced demand was applied towards the desire for less sprawl, i.e. the result of not building a new highway would be denser development in the region. I like how you equated public transit to highway infrastructure cost (i.e. in my example above, replace “new highway” with “new transit line”), the result would be the same, the area around the existing highway/transit line would be less dense. The only difference one could argue would be to say that new development along a transit line would tend to be closer to train stations than new development along a highway… Anyway I never thought of it like that and found that point pretty interesting!