Why Not Build More Roads?

Why Not Build More Roads?

The traffic on Rockville Pike is only getting worse.  Just yesterday, BethesdaNow.com reported that our county’s second most congested intersection is where the Pike crosses Nicholson Lane (click here for that piece).

The White Flint Sector Plan includes a multi-pronged approach to improving our traffic, including building an actual street grid to diffuse it and beefing up transit options like Bus Rapid Transit.  But, I’m often asked “why not build more roads?”

The shortest answer to this question is that, aside from roads being incredibly expensive, “if you build it, they will come.”  What do I mean by that?  Wired Magazine has taken an in-depth look at this very concept, called induced demand:

[I]f 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.

Read the full piece by Adam Mann, which includes more of the “why’s” and “what now’s” by clicking here.

Lindsay Hoffman


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