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Here's what it takes to maintain the decades-old Interstate Bridge

The bridge requires about $40,000 worth of grease a year to keep it in shape.

VANCOUVER, Wash. — The Interstate Bridge first opened on the Columbia River in 1917, replacing a ferry system that connected Portland and Vancouver. A second span of the bridge opened in 1958 to divide northbound and southbound traffic. 

The push to replace the decades-old bridge, called the Interstate Bridge Replacement Program, is moving forward. But until a new bridge is built, the old one must be maintained — and that takes a lot of work. 

The Oregon Department of Transportation has a team of nine full-time employees who maintain the bridge, which is jointly operated by both Oregon and Washington. 

Marc Gross has been the leader of that team for 20 years as bridge supervisor. He gave KGW a tour of the Interstate Bridge to show how the bridge is maintained. 

The bridge is capable of lifting an 1,800-ton span of bridge deck to create clearance as high as 179 feet from the water surface. The lift is accomplished by relatively small electric motors, with 6,500 to 9,000-ton counterweights doing most of the heavy lifting.  

Credit: Tim Gordon, KGW

The bridge has withstood the test of time thus far, but likely would not withstand a major earthquake like the kind eventually expected from the Cascadia subduction zone off the Northwest coast.

Maintaining the bridge includes lubrication of 6.5 miles of heavy steel cables that are part of the lift system. Some parts require greasing every 15 lifts or so. The vertical cables get an annual greasing that takes two summer nights and multiple bridge lifts to accomplish. The bridge requires about $40,000 worth of grease a year to keep it in shape.

But most of the day-to-day maintenance involved equipment like cameras, sensors and gates.

“A lot of our maintenance stuff comes with the electronics and the sensors and the computers that run the bridge and the contacts — we do a lot more of that electrical maintenance and programming maintenance,” said Gross.

The bridge, which decades ago required workers to wave flags to stop traffic, is much more efficient now.

“So now we’ve got bridge tender running the functions of what used to take three people on every given shift to (do),” said Gross.

Credit: Chris McGinness, KGW
Gross took a KGW News crew up approximately 13 flights of stairs to the very top of the bridge — over 230 feet above the Columbia River.

Gross knows a new replacement bridge is eventually coming. He said he’s still got a few years to look over the bridge. Then he’ll be sharing his knowledge with the next supervisor.

“Because somebody else will be most likely running the bridge and dealing with IBR (Interstate Bridge Replacement), getting a new one alongside this old thing and keeping both of them ready to go — and so that will be a chore for somebody, and I’ll do my best to give off all the information to keep this one going long enough for them to do that.”

Details of the top anticipated features of a replacement bridge are expected to be released by IBR in January 2022, as part of the new replacement plan.



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