Wednesday, March 22, 2006

Human beings and their transportation

With all the talk about the Greater Toronto Transportation Authority (GTTA) that will be created in tomorrow's provincial budget, there was a timely story on the CBC radio program Ideas last night. It was all about traffic engineering and human responses to the design of road systems.

Since you probably won't be buying the audio cassette, I'll tell you one of the things that I took away from the program. You may have heard the idea before that if a new lane on a highway is built, it does nothing to reduce congestion because it will lead to more people using the highway. The capacity is increased, but the quality of life is not improved for any of the road users since they still end up stuck in traffic instead of "spending time with their families" (as the politicians like John Tory like to dream).

In order to consider the effect of adding tolls on a highway, like on the DVP or the QEW, the person interviewed in the show pointed out that the reverse is also true. If a highway is removed or limited with tolls (fewer people choose to take it), many politicians and traffic engineers have said that this will just increase traffic on neighbouring streets. This is something that concerned me on a personal level, since I don't want more people racing along on the streets that I ride my bike on. However, this expert (I wish I could tell you his name) indicated that this idea of increased local traffic is not true at all. The result is that car traffic may go up slightly on neighbouring streets, but most of the car traffic simply disappears. People find alternate ways to get to work.

The example he gave was in San Francisco where they chose not to rebuild the highway destroyed in the earthquake. They monitored traffic on neighbouring streets waiting to see the numbers spike. The spike never happened.

I better stop paraphrasing there, just in case I'm approaching copyright infringement. If you get the chance to listen to the show, I recommend it.

I suspect that the same principle would apply to public transit where a viable transit option exists. If there were an extra subway train running where a full subway corridor currently runs, the new subway would fill up soon as people moved into new buildings, sold their cars or made other changes to their lifestyle. In our situation though, for many parts of our city, a viable competitor to the car doesn't exist. This means we have the opportunity to create a whole new option for people in many parts of the city. Greater options can lead to real improvements in quality of life.

So when we consider how the GTTA should encourage money to be spent in the next few years, we have a choice to make. We can create a system that gives options to people in the suburbs and outside of the subway corridors, or we can continue to force car loans, car insurance, car collisions, and car pollution on the entire population.

Darren J 3/22/2006 11:06:00 PM


I've listened to this show before. I think this principal (that people adjust their commuting behavior) is widely known, at least among policy makers and experts, although not necessarily among the general public. I've seen it noted in op-ed pieces in the papers over the years.

A similar principal is that in time studies, people generally spend the same amount of time on transit each day. That is the closer we live to work or shops or friends, the more likely we are likely to walk or cycle. The further we live, the more likely we are to take a faster form - car or transit. Or conversely if we have a car a available, then a trip to the suburbs to shop or work becomes feasible, if we don't have a car than we limit our choices to those nearby.
It may be widely known, but I think the expert's point was that it's sometimes ignored in practice. It's not surprising that politicians would ignore it if their constituents don't know about it, but for traffic specialists and city planners to ignore it reveals that they assume the car is the ultimate form of transportation for the future.

Thanks for pointing out that other principle. It's quite relavant to why transit and walking do not happen much in suburban areas. This is where most people need to find out about the wonders of a nice set of fenders and a good raincoat!

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