There’s been a bit of controversy of late about the the proposal to add lanes to the I-5 bridge that connects Portland with Vancouver, WA. 

Some folks think a wider Columbia River Crossing is a great idea, since they think it’ll ease rush-hour congestion.  Others are opposed, arguing that a wider road would a) funnel more cars into Portland, b) fuel sprawl in suburban Clark County, and c) ultimately be self-defeating, since the extra lanes and extra sprawl will soon attract more drivers, who’ll clog the new highway despite the extra lanes. 

Unsurprisingly, most bridge boosters have dismissed the naysayers’ concerns. Washington’s and Oregon’s growth management systems, they claim, will eliminate the specter of sprawl; and tolls on the bridge will prevent the reemergence of congestion.

In today’s issue of The Oregonian, Portland Metro Council president David Bragdon says some exceptionally smart things about the controversy. In a nutshell, Bragdon thinks that the boosters (including the state departments of transportation) simply aren’t taking concerns about new traffic seriously enough:

The way in which these projects have a history of defeating their purpose is when they attract more traffic than expected and create more congestion, rather than solving it. I am well aware the modelers claim that won’t happen in this case, but you need to look at the model and the modelers before accepting that assertion.

Bragdon clearly understands the most salient fact: new road capacity on a crowded urban highway almost always spurs the growth of traffic.  And he thinks the state departments of transportation haven’t done a good job of explaining why the “if you build it, they will come” phenomenon doesn’t apply to the Columbia River Crossing:

When the two state DOTs (really the highway divisions) are asked about induced demand, they cite the mitigating factors above, which are valid, but they ultimately rest their case on two key statements that are unproven—and that the two DOTs will not allow to be scrutinized independently.

Interestingly, Bragdon is generally supportive of  a new I-5 bridge.  He just wants it done right, and honestly.  To me, that shows a thoughtful and nuanced take on the issues:  being supportive of a highway project doesn’t mean that you have to be blind to empircal evidence about what wider roads can do to traffic volumes.

Bridge photo courtesy of Flickr user Devlyn under a Creative Commons license.