Will Better Public Transit Reduce Traffic Congestion?

It is quite common for advocates of transit to argue that such improvements will reduce traffic congestion.

But advocates must be very careful when stating this.

While I am confident that quality transit coupled with effective transit incentives will take car trips off of roads, I am not at all sure that even the best transit can noticeably reduce congestion (a congestion reduction that is so substantial that motorists are easily able to see congested conditions become free-flowing conditions).

Motor vehicles consume such an immense amount of space, per traveler, that even a tiny number of motorists can quickly fill a road to congestion (see image photo 40PeopleFig7.3Insertedseries). Therefore, it seems to me that if a city does NOT have congestion, there must be something terribly wrong with the city, since it only takes about 40 motorists to gridlock a street – not a lot of people.

Even if large percentages were using transit/carpools/bicycles, etc., and only a small percent are single-occupant vehicles (SOVs), it only takes a small number of SOVs to create congestion.

Even if it were true that transit could noticeably reduce congestion, induced demand and the triple convergence would quickly fill up the newly free-flowing roads. The triple convergence informs us that in any reasonably healthy community, roadway space that is freed up will quickly be filled again because the newly-available road space induces new car trips that would not have occurred had the road not been made free-flowing. Those new trips come from motorists converging on the new road space who were formerly driving at non-rush hour times, using alternative routes, or traveling by bicycle, walking or transit.

I therefore believe that it is strategically problematic to claim in a debate with those who oppose improvements for transit (and who instead want to spend money to make motor vehicle travel easier) that transit reduces congestion. The motor vehicle advocates are placed in a strong debate position when the argument is framed in such a way as to suggest transit reduces congestion, because almost no one is able to point to a single community where transit has noticeably reduced congestion, even where there is good transit. Are the great cities of the world – Rome, Paris, DC, NYC – free of congestion because they have quality transit? I think most everyone perceives each of those wonderful cities to be grid-locked.

Therefore, argues the motor vehicle advocate, transit is wastefully ineffective.

I think we are in a much better debate position when we don’t get caught up in that sort of debate framing. Instead, the point I try to make is not that transit will significantly reduce congestion, but that it will provide choices. One can choose to get stuck in traffic by stubbornly continuing to drive a car. Or one can decide they are unwilling to tolerate the congestion, and instead choose to use transit (or better yet, live closer to their destination). Or avoid rush hour. Or take an alternative route.

Are there effective tactic for reducing congestion? Yes. I am supportive of congestion-pricing and proper parking management as an effective, if politically unrealistic, strategies to reduce congestion.

The key, in my opinion, for a healthy community is not to fight against congestion. Fighting against congestion too often leads even the most progressive communities to not only set up ineffective, “empty bus syndrome,” transit systems – which gives transit a black eye, but also encourages the default solution: road widening. While I don’t tend to say this publicly, I am passively supportive of congestion because it delivers compact, higher density development, more transit use, and less severe crashes, among other community benefits.

In sum, my vision for a healthy community is not to strive to reduce congestion (which may not be possible at the local level, anyway, and can easily be counter-productive), but to ensure that there are transportation and lifestyle choices so that one can choose to opt out of what is probably intractable congestion. I believe it is a mistake, tactically, to suggest that transit will reduce congestion.


Filed under Transportation

10 responses to “Will Better Public Transit Reduce Traffic Congestion?

  1. imcleod

    Excellent post. In the 1990s, British Columbia’s provincial government took a passive “let the congestion build” approach to transportation development in Metro Vancouver, an area with a population of 2+ million. The administration elected in 2001 has taken heroic steps to increase highway capacity, in concert with the regional transportation authority. The capital costs have not been well reported, but an educated guess would put the total at around $7 billion over the past decade, with more to come. The impact, in my view, has been to move congestion around, to the benefit of long-distance commuters like me. In its 2014 survey, Tomahawk (a company that sells GPS gizmos to motorists) ranked Vancouver as the most congested urban area in Canada and one of the most congested in North America.

  2. imcleod

    Je m’excuse. The brand name above should be TomTom, not Tomahawk. Tomahawk is the name of a street in Apache Junction, AZ.

  3. jmc4now

    Hi. Are there any new models out that address the urber, lyft, bridj. new GPS/crowd sourcing technologies impacts upon mass transit?

    I’m in Boulder CO. Of late we’ve been in the news b/c of “right sizing” streets, reducing traffic lanes for bike lanes.

    Recently I came across “induced congestion” and “triple convergence”. I had thought more mass transit = less congestion. For us, everything is not working – arguing, bikes vs cars sort of thing. I suspect it has to do with an uneducated public making communication not possible.

    Boulder has about 100,000 people but we have +60,000 commuters a day, 1/2 from US 36, main artery to Denver, 1/2 from the L towns (other big towns in Boulder County, its population 300,000). The quandary is: If more roads invite more congestion, mass transit offers a choice but no reduction congestion, and our population is growing, just not in Boulder (We’re anti-growth.) – then what? I’m not aware of any model that incorporates new technology, a “Bridj.com” service with a really good transit service. (Not what RTD currently offers us, really good mass transit service. They’ve had flat ridership for years, and are 80% subsidized. RTD is rated OK, but this might be a case of “smartest person in a room full of dummies”.)

  4. Thanks for reading my material and thanks for your interesting comments. I ALSO live in Boulder and am very well aware of the right-sizing controversy. I made the motion on the Boulder transportation advisory board a few weeks ago to recommend Council proceed with them. I don’t know of anything Boulder can do that is more cost-effectively beneficial than right-sizing (I’ve been in transportation planning academically and professionally for over 30 years). I hope Council shows needed leadership and not only makes Folsom and Iris permanently right-sized, but also does it for other streets. A great many streets and intersections in Boulder are over-sized. Yes, I’ve written about induced traffic and the triple convergence (usually mention them both in my speeches as well). Alternatives to driving tend to induce new car trips when road space is freed up. And congestion is NOT something a city should try to reduce. First, congestion in a city is a sign of a healthy city (cars take up so much space that if things are not somewhat congested, it may be a sign of city woes). Second, nearly all of the tactics used to try to reduce congestion are toxic for a city (wider roads/intersections, more parking, synchronized traffic lights, stopping development, reducing development density, etc.). Since it is nearly impossible to reduce congestion (and it is not clear to me that we should try), it is much more beneficial to provide alternatives to congestion for those who would prefer to avoid it. Bike/ped/transit facilities, more street connectivity, and more housing in town centers, for example). BTW, the Soviets never learned this (which is why their society collapsed) and the US seems to also be unable to learn this: The only effective way to reduce congestion is to price roads (tolls) and price parking. Boulder and Colorado need to do a LOT more of that. Oversized car infrastructure, free roads, and free parking are artificially inducing a lot of car trips that would not have occurred had we not done those things. Who needs enemies when we have ourselves? If you want more walking, cycling, or transit, it is NOT a matter of providing better services for those forms of travel. It is about reducing the space allocated to cars, reducing car speeds, reducing motorist subsidies, and reducing distances to destinations. Dom

  5. jmc4now

    I just saw this … Are you still on the transp bd?

  6. Yes I am. Thanks for visiting my blog.

  7. jmc4now

    Any take on the Lafayette no vote RTD tax other than the obvious one, people didn’t like the idea of a property tax absent an agreement with RTD what they’d be paying.

    Also I attended one of the Denveright charettes, went to the transit workshop, spoke w/ the head transit planner (woman, name escapes me). She said RTD is a regional planner which is (I think.) why Denver going its own way with local transit plans. Do you know anything about RTD as a regional transit provider only? It was news to me the RTD doesn’t see itself as provider of the local pieces.

  8. I can only speculate about the No vote in Lafayette, since I did not learn anything about that issue in the past. My guess is that very few expect to be riding a bus — even with a bus pass. That thinking is likely due to a common experience in America: Nearly all drivers park for free wherever they drive, which is a huge subsidy and large incentive for driving (a fertility drug for cars, as Shoup would say). I don’t know anything about the issue you raise about RTD as a regional provider. I would like to learn more.

  9. jmc4now

    Downtown Boulder should be a woonerf. I get her name later today, and send it to you. She can explain (If she will.) as I heard it from her. She and other planners (land use and transportation, #s of categories) said: the Denveright process will get what the public wants and then go back to the public with the cost/how to provide. This led me to ask her about the RTD component (more routes, more frequent services is what people were putting on the up on the boards) which led to her assertion “RTD regional provider.” She knew what she was saying, especially to me, because I told her I was from Boulder, at the charette to learn what Denver was going to do, transit. Have you been to the Denveright site, you should check it out, especially the transit component. I had this conversation with Will Toor because Denveright includes regional issues, I was arguing for a bigger participation in Denveright from Boulder County since we have intercourse with Denver.

  10. I love woonerfs and would love to see them in Boulder. They are also called “shared streets.” Boulder has a lot of oversized streets that need to be necked down for slower, more attentive, safer driving, not to mention dramatically improved quality of life and economic health for businesses. I look forward to more info about RTD.

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