Thursday, August 6, 2020
Aug. 6, 2020

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Repairs to close part of I-5 Bridge in 2019

Northbound lanes will be shut down for several days or weeks

The Columbian
Published:

Commuters who use the Interstate 5 Bridge may have the perfect excuse to take a long vacation in 2019.

The Oregon Department of Transportation announced plans to close the northbound span of the bridge in late summer or early fall of 2019 to make much-needed repairs to the lifting system of the southern tower.

ODOT spokeswoman Kimberly Dinwiddie said bridge engineers are designing a project to replace a cracked axle, or trunnion as it’s called, in the southern tower. The work is critical for long-term safety and effective drawbridge operation, but it’s going make an already terrible northbound commute much worse for several days or as much as a few weeks.

“We do realize it’s a big inconvenience for travelers, but this axle is pretty much the backbone for safe operation of this drawbridge,” Dinwiddie said. “There’s a crack in the axle. If it continues to grow, the bridge could get stuck in the upright position or — we could have a counterweight …come crashing down on the bridge deck.”

The trunnion in question is part of the bridge’s original draw system and will be replaced on its 102nd birthday. The axle is 20 inches in diameter and 4 feet long. Inspectors discovered a 4-inch crack inside it during an ultrasonic test about 2.5 years ago. Since then, the crack grew to about 6.5 inches, but ODOT engineers believe the axle will be safe up to the time of replacement.

Oregon and Washington will split the project costs. Dinwiddie said high-end preliminary estimates are $10 million.

Engineers believe the crack is not the result of age, but rather the unintended consequence of a 1958 pulley system upgrade. In an effort to cut costs, engineers opted to weld over grooves in the axle’s surface rather than replace it with one better fitted to the new pulleys. The plan did save money, but it also created new stress points in the material.

“Our bridge engineers tell me back then they didn’t have knowledge base to know that cracks would develop from welding,” Dinwiddie said.

ODOT isn’t sure yet how it will reroute traffic. While it’s definitely going to cause problems for daily drivers, it could have international implications because the trucking and maritime shipping industries also will be impacted.

For longtime residents, ODOT’s announcement will be all too familiar.

The project mirrors a repair made to the northern tower on the northbound side of the bridge in 1997. Back then, a crack in the trunnion was discovered under an emergency scenario and the project had to be completed in less than a year. Officials planned for a three-week closure, but the work was finished in about seven days. The project cost between $5 million and $6 million. The closure caused a major traffic headache on both sides of the river, but the silver lining now is that the public will have significantly more time to plan ahead.

“This time we have at least three years, so people can start planning for multiday or -week closures so hopefully they won’t be caught off guard,” Dinwiddie said.

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