The northbound span of the Interstate 5 Bridge will close to all traffic for nine days beginning Saturday. All freeway traffic will use the southbound span while crews work to replace a cracked trunnion and other parts of the northbound bridge's lift system. At top: Crews will use a barge-mounted crane to lift down the worn-out components of the lift system and replace them with new parts. (Photos by Alisha Jucevic/The Columbian)Photo Gallery
Barring any more last-minute delays, the big Interstate 5 Bridge trunnion repair project is set to begin Saturday, kicking off the scheduled nine-day closure of the northbound span of the twin bridges and use of the southbound span for all freeway traffic.
The closure was originally scheduled to begin Sept. 12, but the Oregon Department of Transportation announced on Sept. 10 that it would delay the project to ensure Portland region’s freeway system kept running smoothly amid widespread wildfire evacuations in Oregon. The following day, ODOT announced the new Saturday start date.
The wildfires threw a wrench into the proceedings, but there were no other last-minute hiccups during preparations for the project itself, according to ODOT spokesman Don Hamilton.
The pieces were all in place last week, and remain ready: new trunnions and sheaves to replace the worn-out parts of the lift span, temporary falsework to support the bridge and counterweights, a barge-mounted crane to hoist the parts to the top of the tower and a pair of “zipper” machines for the moveable barrier that will allow the middle lane of the southbound span to function as a reversible rush hour lane.
A pair of nearby preparation projects also wrapped up ahead of the original planned start date. The Washington State Department of Transportation’s new Traffic Management System along I-5 in Vancouver was up and running last week, according to spokeswoman Tamara Greenwell, and the agency plans to operate a round-the-clock emergency operations center team to respond to any bridge-related issues.
C-Tran has finished preparing to use a new bus-on-shoulder lane along southbound I-5 leading to the bridge. Sept. 11 was the last scheduled day of operator training, and the lane was considered “live” as of last week, according to C-Tran spokeswoman Chris Selk.
Buses will be able to use the shoulder to bypass congestion if freeway traffic drops below 35 mph. Opportunities to use the lane have been rare thus far, Selk said, but C-Tran expects that to change once the closure starts.
The traffic transfer to the southbound span will begin with single-closures tonight, Hamilton said, following the same schedule that had been planned for one week earlier. The shift will take place in stages throughout the night, with lanes only closing one at a time in order to minimize disruption and avoid traffic backups.
“This all needs to happen gradually,” he said.
Crews will begin closing lanes on the southbound span starting at 8 p.m., and will close one lane on the northbound span at 9 p.m., following by a second at 10 p.m., with the last northbound span lane closing at midnight. At that point, northbound traffic will shift to the southbound span.
The northbound lanes will cross over the median at Hayden Island and transition back just past the north end of the bridge. The speed limit on the bridge will drop to 40 miles per hour for the duration of the project.
“It’ll be paved and striped and very clear,” Hamilton said.
The direction of the southbound span’s center lane will match the flow of rush hour traffic. The morning configuration will be two lanes southbound and one northbound, with two lanes northbound and one southbound in the afternoons. The zipper machine will drive through and adjust the barrier starting at 2 a.m. and noon each day, including on the weekends.
WSDOT and ODOT have spent months urging commuters to work from home, take public transit or plan alternate driving schedules next week. Even so, motorists should brace for congestion.
Traffic levels along the I-5 corridor dropped steeply during the early weeks of the COVID-19 pandemic, but subsequently recovered and have been holding at about 10 percent below pre-pandemic levels in recent days, Greenwell said.
“We’re hoping that with the extensive public outreach we’ve done to date to share this message, some folks will delay or shift their trips, bike, take transit, or work from home or another location – if possible,” Greenwell wrote in an email. “People will likely be diverting to use other roadways and should expect heavy traffic, congestion and long delays traveling throughout the region on I-5, I-205, SR 14, I-84, and local streets in Vancouver and Portland.”
