Bridge traffic didn’t grow with county

In a decade of growth in Clark County, a bedroom community where a third of the workforce commutes to Portland, you’d expect to see traffic on the bridges crossing the Columbia River to worsen.

It didn’t.

Traffic rose just 1 percent from 2002 to 2011, according to the most recent counts available, even as the county’s population grew 17 percent.

Critics of the Columbia River Crossing project have argued these figures cast doubt on traffic forecasts used to justify plans for a $3.5 billion new Interstate 5 bridge.

The project’s environmental impact statement estimates that, if no action is taken, 184,000 cars a day will cross the I-5 bridge in 2030. Planners say daily traffic congestion — which engineers define as freeway traffic that moves at less than 30 mph — will increase, from four to six hours a day on I-5 to 15 hours in both directions by then.

Yet over the past few years, drivers have taken their feet off gas pedals for a variety of reasons — high fuel prices, a poor economy and generational shifts.

“People are driving less,” said Portland economist Joe Cortright, a critic of the bridge project.

Planners estimated 143,700 vehicles would cross the I-5 bridge on the average weekday in 2010 –13 percent higher than the 126,900 actually experienced, Cortright points out.

Project planners look past blips in the near term to focus on “long-range needs in the corridor,” Mandy Putney, spokeswoman for the project, wrote in response to The Columbian’s inquiries. “Traffic forecasts are not based simply on projecting recent trends, but on developing future forecasts of transportation use based on other variables including population and employment forecast.”

Long-term aside, what has happened to those drivers in the short term?

The Great Recession certainly played a role. Workers lost their jobs in years of record layoffs.

“Even those employees who remain employed tend to reduce their discretionary spending. This reduces travel for the purposes of shopping, entertainment and various other activities,” Putney said. “Part of what we have seen in the traffic counts in the I-5 corridor is a reduction in the amount of off-peak travel, which is consistent with reductions in discretionary trips. Traffic volumes during the peak period, which includes most of the commuter work trips, have remained nearly constant.”

Scott Bailey, a Washington state regional labor economist, agreed that the economy has dragged down driving.

“With the recession, there was a big drop in miles driven, with very little recovery there,” Bailey said. “Clearly, commuters were hit by job losses. Bridge traffic is not just commuters. It’s also shoppers, people visiting family, business trips and freight.”

Other forces

The economy isn’t the whole story, however. Traffic started to level off before the economy officially crashed in December 2007.

“The recession argument doesn’t wash. The decline in traffic on the I-5 bridge began well in advance of the recession, and traffic continued to decline even after the economy got better,” Cortright said. “The long-term trend has everything to do with the fact that gasoline cost in real dollars has doubled.”

The real price of gas declined from 1980 until 2000, and then started climbing, Cortright said.

“People respond to prices in a whole series of decisions: how much they drive, what kind of vehicles they drive, how far they travel, how far they look for jobs and houses,” Cortright said.