Highways and Congestion

For John, BLUF:  Lies, damned lies, statistics.  Nothing to see here; just move along.

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At Wired Magazine, in the "What's Up With That" section we have an article by Mr Adam Mann, with an assertive title, "Building Bigger Roads Actually Makes Traffic Worse".

...if there’s anything that traffic engineers have discovered in the last few decades it’s that you can’t build your way out of congestion. It’s the roads themselves that cause traffic.

The concept is called induced demand, which is economist-speak for when increasing the supply of something (like roads) makes people want that thing even more. Though some traffic engineers made note of this phenomenon at least as early as the 1960s, it is only in recent years that social scientists have collected enough data to show how this happens pretty much every time we build new roads. These findings imply that the ways we traditionally go about trying to mitigate jams are essentially fruitless, and that we’d all be spending a lot less time in traffic if we could just be a little more rational.

Yes, here are the numbers for the induced demand in the automobile transportation area:

A review of transport research suggests that the elasticity of traffic demand with respect to travel time is around −0.5 in the short-term and −1.0 in the long-term. This indicates that a 1.0% saving in travel time will generate an additional 0.5% increase in traffic within the first year. In the longer-term, a 1.0% saving in travel time will result in a 1.0% increase in traffic volume.

There is an upper limit here, isn't there?  If not the total number of cars in an area, then the total number of people?

What really bothers me about such arguments is that there is not a discussion as to what the natural limit might be.  About a decade ago there was a letter in The Boston Globe complaining about how, if the mixing bowl at the intersection of the 93 and 95 Interstates north of Boston was to be fixed it would only result in more people driving.  The letter author didn't comment on the possibility that a lot of those folks are currently driving at "street level".  Wouldn't it be nice to bring that traffic up out of the neighborhoods and put it on the roads designed to handle it?

Then there is that other economic term, "opportunity cost".  What is the next best use of one's time and money?  If you are trying to fix something around the house and you need some parts, but all the roads are jammed, do you go sit in traffic, go "street level" or just forgo the repairs, figuring to get the parts you need at some other time?  Why should road planners decide if and when you go to the local Home Depot or Lowes?  By limiting road construction that is exactly what is happening.

Of course, you could live in a city, where everything is within walking distance or there is a bus.  This is a vision close to the hearts of Progressives.  End that urban sprawl.  I guess it is a view, but I suspect it is a view that exists in the minds of those who already have theirs.  They live in Lexington and Concord and Carlisle.  This is a view that would condemn to the congested ghettos those people who wanted to get out and have a lawn and trees.

And what about work. Since moving to Lowell I have worked in Wilmington (14.69 miles away), Andover (twice) (6.05 miles slow route and 8.68 miles via freeway) and Sudbury (between 25.21 and 31.26 miles, depending on route).  Not walking distance and there is no public transportation, so should I just have moved each time I got a job change (within the same company that is)? There is a germ of an idea in the article, but it needs a lot more development.

Regards  —  Cliff