I-5 bridge project: Predictions of traffic catastrophe don’t materialize

As a nine-day project on the Interstate Bridge wraps up this weekend, planners say their forecasts calling for a nightmarish regionwide traffic catastrophe failed to materialize. State officials say they put out messages of dire traffic concerns because it’s important to do so. “If the problems weren’t as bad as […]

As a nine-day project on the Interstate Bridge wraps up this weekend, planners say their forecasts calling for a nightmarish regionwide traffic catastrophe failed to materialize.

State officials say they put out messages of dire traffic concerns because it’s important to do so.

“If the problems weren’t as bad as we feared, I don’t think that means we overstated the case,” said Don Hamilton, an Oregon Department of Transportation spokesman, “It means people followed our advice.”

Oregon Department of Transportation officials warned drivers they could see significant delays across the region and onto surface city streets due to the $13 million project to replace a key component of the aging bridge, which required shutting the northbound span on Interstate 5 on the bridge spanning the Columbia River.

Friday marks the last weekday closure, which funneled all vehicles onto the southbound span throughout the project, with two lanes of travel for southbound drivers in the morning switched to accommodate the evening return home for tens of thousands of Clark County commuters. Construction is expected to continue through Sunday. A single lane closure on the southbound span begins Monday and will last for one week as crews take away all the machinery.

Transportation officials saw a busy initial weekend as people either tested how bad the closure would be or forgot about it. On the following week days, they also saw a predictable uptick in traffic diverting to Interstate 205. But travel patterns largely followed the normal cycle: Evening trips northbound across either of the two bridges were a slog, but that’s typically the case with scores of residents working on the Oregon side of the metro area, even during a pandemic.

The phenomenon of road experts predicting a traffic apocalypse that never comes is one that has played out before, in Oregon and elsewhere around the country.

And for some transportation observers, it’s not simply an illustration that authorities can frighten people into shifting their travel plans for a short-term purpose. It also reflects, according to one prominent economist, proof that more vehicle capacity – think, freeway lanes – isn’t necessary. After all, if taking away two lanes of critical interstate travel didn’t destroy the system, people can find new ways to get around if they have to.

“Traffic acts more like a gas than a liquid,” said Joe Cortright, a Portland economist who runs the website City Observatory. “It expands (and compresses) to fill the space available.”

“When traffic capacity is limited people adjust their behavior; when capacity is expanded, people drive more (and further),” he said in an email.

To Cortright, the bridge part replacement project’s relative blip on the region’s transportation flow is more evidence of that familiar pattern.

He rattled off a variety of examples from around the country – the 2007 collapse of Interstate 35W in Minnesota, the multi-day shutdown of Interstate 405 in Los Angeles through Sepulveda pass, a fire and subsequent closure of Interstate 85 in Atlanta in 2017 and the 2019 closure of the Alaska Way Viaduct in Seattle; “highway officials predict gridlock and it doesn’t happen, because enough people have a lot of flexibility about when, where and how they travel,” he said.

Hamilton said “there’s some sense” to Cortright’s views, but he said it’s impossible to know all the factors at play. “We warned them, and people listened,” he said.

“People I think had some experience in recent months of staying home, traveling at different times of day, staying off the road if they could,” he said, citing the COVID-19 pandemic. “I think in some ways that may have become accustomed.”

For the 2020 closure, C-Tran, the public transit service in Clark County that offers several routes into Portland, instituted two new projects that allow buses to travel on the shoulder on the approach to I-5 on the Washington side and on both sides of the river over the Glenn Jackson Bridge, which carries I-205.

Chris Selk, a C-Tran spokesperson, said the agency has seen “significant” ridership increases despite the ongoing COVID-19 pandemic and bus capacity capped at 15 riders for its standard 40-foot buses due to social distancing guidelines still in effect. More people rode three of its five bus lines that cross into Oregon, she said, and ridership overall was up 35% on those commuter routes through the first three days of this week compared to the week before construction began.

“It’s been good to see that people are taking advantage of transit,” Selk said, noting that one of the routes had roughly double the ridership during the I-5 bridge closure than before the project.

The new initiative allows buses to travel on the freeway shoulder when overall freeway traffic is less than 35 miles per hour.

As of Thursday, Selk said C-Tran buses have used the shoulder to bypass congestion 24 times since crews began work on the project on the Interstate Bridge, with all but one of those instances occurring on I-205.

But even with more traffic diverting to I-205, the buses did not frequently travel below 35 mph. On Tuesday, for example, buses used the shoulder eight times on I-205 throughout the day due to slow traffic. According to C-Tran figures, buses crisscrossed the bridge 132 times that day.

C-Tran and ODOT will keep allowing buses to use the shoulders after the bridge project wraps up, though Selk said the I-205 program will be classified as a “pilot project” for one year to see how it works.

Hamilton said similar predictions of traffic doom in 2018 involving full ramp shutdowns on Interstate 84 failed to live up to calamitous predictions.

Oregon also has a track record with the Interstate Bridge, and the very same part that’s the centerpiece of this lengthy closure, failing to spark car panic citywide. In 1997, when engineers replaced the same part on the other span of the bridge, the state issued similar guidance about a traffic apocalypse. Those, too, didn’t occur.

“The warnings were correct. We just got an outstanding showing of support from the community as far as changing their commuting habits,” Katy Tobie, spokeswoman for the Oregon Department of Transportation, said at the time.

Hamilton brought up the 1997 example too, and said it is what it is. “It was a successful effort,” he said, of notifying the public.

Cortright, the economist, wrote in 2019 on the same issue when Seattle failed to see its city fall to ruin when the famed viaduct came down along the west side of downtown. He said cities should use that an example of how to better evaluate making changes to its transportation system. “This ought to be a signal that road diets, which have been shown to greatly improve safety and encourage walking and cycling, don’t have anything approaching the kinds of adverse effects on travel that highway engineers usually predict,” he wrote.

— Andrew Theen; [email protected]; 503-294-4026; @andrewtheen

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