Using the Congestion Argument to Push Transit Investment

Is the claim that transit can reduce congestion a specious one?

The Texas Transportation Institute released its urban mobility report a few days ago, something that most readers of this blog probably picked up from other sources. The study demonstrated that the average American spent one hour less in traffic in 2007 compared to 2006 — a total of 36 hours annually, which comes out to around 10 minutes of traffic per work day. Some metropolitan regions suffered far more than others: 70 hours for the average per person in Los Angeles, compared to only 11 for those in the Buffalo area. But the overall message was negative; despite the slight decline in traffic, Americans still suffer far too much from traffic.

Alternative transportation advocates immediately seized on the report to argue for changes in the way we fund and invest in transportation. Matt Yglesias said if “we directly charged people fees to enter congested areas at peak times, we would not only put a much bigger dent in the congestion problem but we’d do it in a way that raised substantial sums of money that could be used to fund improvements in transportation alternatives. That would give drivers uncrowded roads, give non-drivers better commutes, and give everyone a bigger set of options.” Elana Schor at Streetsblog argued that transit and dense urban development were solutions to many of our congestion problems.

Yglesias’ is a bad argument because it implies to automobile users that transit is acceptable because it will force other people out of their cars and into buses and trains, therefore clearing the freeways for the first users and their cars. We want to be designing transit systems that are attractive in and of themselves. But otherwise, is this true? Can we positively associate transit improvements with congestion reduction?

In order to answer that question, I took population and transit ridership data from the top 25 metro areas and compared them to the Texas Transportation Institute’s annual wasted hours information. I then plotted the information (Excel) and produced the following charts. Before I delve into the details, I’d like to point out that this is very rudimentary information that doesn’t necessarily prove anything but rather is meant to provide further fodder for discussion on this issue.

Here’s the basic conclusion: the correlation between annual transit trips per capita and hours wasted in traffic per traveler seems to be weak at best — or nonexistent. New York is, as usual, a far-off outlier that skews the chart a bit. Below are the top 25 metro regions plotted based on this information:

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What’s interesting is that the population size of the metro area seems to have a slightly closer connection, below, with smaller metro regions at least capable of having less congestion compared to larger metros. New York and Chicago, compared to L.A., have many fewer hours wasted per capita, which implies that a very large transit system and a focused inner city core can play an important role in reducing traffic. On the other hand, D.C., which has one of the nation’s most patronized transit systems, still has the nation’s second-highest levels of congestion.

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Just for kicks’ sake, I compared metro areas that have invested significantly in their transit systems in the period between 1982 and 2007 with additional traffic delay hours during that period. I classified a “major investment” as the opening of at least one new major rapid transit line. This is a bit biased towards rail investments — you could argue that a city had improved its bus services dramatically in the same period — but I did not have bus-related information on me. This chart demonstrates a limited effect of new transit investments on traffic, which increased dramatically in D.C. despite its considerable spending on Metro, but a stronger effect in Pittsburgh; the overall spread for “major investment” metro areas as compared to “no major investment” areas is similar, however.

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What does this data mean? Is there no point in investing in transit if there’s little connection between congestion relief and transit offerings?

Obviously I don’t think so. I think the bigger issue is that we need to realign our arguments in favor of transit away from its benefit as a congestion-fighting tool and towards its benefits as an alternative and land-use orientation tool.

While I do think that road pricing would be an effective way to clear the roads, I don’t think it’s appropriate from a societal perspective. Eliminating traffic, which may be a direct result of road capacity existing in the first place, is very difficult without the use of tolling; if a free road exists, people are going to use it, and in urban areas, it will become congested. But that’s not necessarily a bad thing if we’re not spending our transportation dollars to invest in new highways.

In some ways, in fact, congestion on the roads is beneficial to public transportation. If operating in its own right-of-ways, transit can be faster than driving, but usually only if there’s at least some traffic on the road. Part of the attraction to transit stems from the fact that it’s a fast, efficient, and reliable alternative, unlike highways in traffic. It loses this attractiveness if roads are car-free, because automobile commutes are usually faster if there’s no traffic. That means that even with a very good transit system, people are less likely to switch away from driving unless the roads they use are congested. If we want higher ridership, we should stop building new roads and keep the ones we have busy.

Transit creation should be pushed also because it can spur dense, mixed-use communities, places that are good for the environment and for the well-being of city cores. But let’s stop making the argument that transit is going to solve congestion problems.