PORTLAND — An eight-lane bridge across the Columbia River would be too small to accommodate future traffic demand unless there is a major increase in the number of drivers deciding to take the bus or avoiding rush hour altogether, according to an engineering firm hired by the city of Portland to consider a smaller Interstate 5 bridge.
Concerned about the mammoth size of the 10-lane Columbia River Crossing currently being proposed, the city wanted to look at a slimmer version.
The engineering firm delivered its assessment Friday during a meeting of the bistate Project Sponsors Council. URS Corp. accounted for anticipated traffic demand in 2030.
“The conclusion that jumped out to us was a capacity issue,” said Ted Rutledge, URS transportation manager based in Denver. “Both northbound and southbound were really at or over capacity. So based on that alone, it’s not going to meet the need.”
However, Rutledge told members of the bistate panel that the project could save $50 million building a slimmer version of the current 10-lane proposal and still meet the multibillion-dollar project’s purpose and need. Bridge planners envision a span striped for 10 lanes but expandable to 12 if needed in the future.
Henry Hewitt, the council’s co-chairman, suggested sending the matter back to city and state transportation planners, who would then deliver a recommendation during the council’s next scheduled meeting on July 16.
Washington members of the council made it clear they were dubious about the eight-lane concept.
URS found that the eight-lane bridge would accommodate only 78 percent of the anticipated traffic demand in 2030. And that assumes the number of people crossing the bridge who ride light rail and buses increases from about 3 percent today to 15 percent in 2030.
Avoiding traffic paralysis on an eight-lane bridge would require aggressive use of carpooling, enhanced bus service and jacking up toll rates from $2 to $3 to suppress rush-hour demand, the firm concluded.
“It’s a big number,” Rutledge said. “There’s no getting around it.”
The concept appeared to be a nonstarter with Clark County Commissioner Steve Stuart.
“I don’t consider paying higher tolls for less mobility effective,” he said. “Charging more for less isn’t creating a better cost-benefit for those people who are paying it.”
The project, with a price tag estimated at $2.6 billion to $3.6 billion, would replace twin three-lane drawbridges, improve four miles of I-5 on both sides of the river and extend Portland’s light-rail transit system into Vancouver.
Given the increase in toll rates likely to be necessary to forestall congestion on an eight-lane span in 2030, Washington Transportation Secretary Paula Hammond said she’s inclined to drop further consideration of the eight-lane option.
“To constrain people’s ability to work in the region, I think is a problem,” she said.
Hammond’s comments generated a heated exchange with Portland Mayor Sam Adams. The mayor said he takes “serious umbrage” with Hammond’s assertion that aggressive measures to manage demand on the bridge somehow artificially constrain traffic, as if adding freeway lanes were an unquestioned foregone conclusion.
Concrete and asphalt are choices, too. “That’s as much social engineering as a carpool,” added David Bragdon, president of the Portland-area Metro council.