In the May 11 issue of Finance and Commerce, Matt Kramer, a local Chamber of Commerce representative lobbying for additional public transit and transportation spending (currently being debated at the Minnesota Legislature) is quoted as saying “Every person who is riding transit is one less person in the car in front of us.”
This is a fascinating quote. First is the use of “us.” So the Chamber of Commerce (probably correctly) identifies riding transit as something someone else does (since “we” are still in the car) and goes on to imply that it benefits us because there will be fewer cars. (Actually he says fewer people per car, but I think he meant fewer cars, not that it would reduce carpooling). And I suppose he could mean he rides the bus, and the car in front has fewer people (or there were fewer cars in front), but I don’t think that’s what he meant, since the arguments in the legislature are mostly about building and operating new facilities–such as LRT lines or freeway BRT, rather than supporting existing buses driving in traffic.
This evokes the famous Onion article: Report: 98 Percent Of U.S. Commuters Favor Public Transportation For Others.
But it also suggests transit reduces auto travel. The converse is almost equally true, building roads reduces transit crowding. But that is not an argument road-builders make. [It is an argument urbanists make against roads.]
Of course, some transit users would have otherwise driven, but many would have been passengers in cars, walked, ridden bikes, or telecommuted. No one really knows what the alternative untaken mode would be. We have models, but the form of those models dictates the answer. Logit models, which are widely used by travel demand forecasters to predict mode choice (and whose development resulted in a Nobel Prize in Economics for University of Minnesota graduate Daniel McFadden), have the property called “IIA”, which is short for Independence of Irrelevant Alternatives. In short, if you take away a mode, IIA means people choose the other modes in proportion to their current use. So let’s say there are 3 modes: walk 25%, transit 25%, drive 50%, and there is a transit shutdown (like in 2004). IIA implies the 25% of former transit users would split 1/3 (25%/75%) for walk and 2/3 (50%/75%) for driving. We all know that is not true (and there are various techniques to try to fix the models and use more complicated functional forms), but the question of what is true is not at all clear.
While there are surveys that have answered those questions, they are all context specific. For instance, Googling turns up a Managed Lanes Case Study report:
95 Express bus riders were asked how long they have been traveling by bus and what was their previous mode of travel before using the bus service. 92 percent of respondents (307 out of 334) mentioned they have been traveling the 95 Express bus before the Express Lanes started. Only, 8 percent of respondents (27 out of 334) began using the bus after the Express Lanes opened. Among them, 50 percent (13 out of 27) had their previous mode as drive alone and none of them carpooled previously. Therefore, 95 Express bus ridership consisted primarily of those who have been using the service prior to Express Lanes implementation and the small mode shift from highway to transit was mostly from SOVs. Note that the number of respondents is too small to make any conclusions (Cain, 2009).
Undoubtedly other services would have different numbers, but transit lines are not generally a direct substitute for driving.
The line of reasoning in the opening quote suggests the primary purpose of transit is reducing auto travel, rather than serving people who want to or must use transit. In other words, building transit is good because it reduces traffic congestion (and almost no one argues building roads is good because it reduces transit crowding).
That is at best a secondary benefit, a benefit which could be achieved must more simply and less expensively through the use of prices as we do with almost all other scarce goods in society, even necessities like water.
Transit today is, in almost all US markets, slower than driving. People who depend on transit can reach fewer jobs than those who have automobiles available. Some people use transit by choice, for instance to save money (if they need to pay for parking), and the rest without choice. In my opinion, it is more important to spend scarce public dollars to improve options for those without choices than to improve the choices for those who already have alternatives. Perhaps ideally we could do both, in practice, one comes at the expense of other.
The idea that transit is for the other person is true for the 95.5% of people who don’t use transit regularly. But it warps thinking that the aim of public transit funding is to benefit those non-transit users.