EVERETT – Repairs to the underbelly of the aging westbound U.S. 2 trestle have started.
The state Department of Transportation is spending $10.8 million this summer to replace large chunks of concrete that have fallen from the underside of the 39-year-old structure.
The trestle is structurally sound and safe to drive.
The 6,000 cars that travel westbound across the trestle at night will be routed underneath the trestle on 20th Street SE while repairs are made, said Amir Ahmadi, the state’s project engineer.
A many as 70 nighttime closures of the westbound trestle are scheduled between now and October, when the repairs are scheduled to finish.
On nights when closures do occur, they are scheduled to start at 7 p.m. and end at 5 a.m. – early enough to avoid affecting the morning commute into Everett.
The closures won’t start for at least three weeks. The work to start converting 20th Street SE into a detour started Tuesday, said Meghan Soptich, a DOT spokeswoman.
About one mile of westbound 20th Street SE, from Highway 204 to 50th Avenue SE, will stay closed until the construction project finishes, she said. It will be used as a staging area for the repair work.
Next week, the state will close eastbound 20th Street SE and a bike lane so that it can be paved, she said.
It will become the detour, once the paving is finished. To do this, the direction of travel will be switched to westbound until the project finishes in October. The bike lane will reopen once paving is finished.
The detour will take about five minutes or less for drivers who approach the trestle on U.S. 2 and Highway 204, Ahmadi said.
“Basically, all we are doing is taking them down below,” he said. “It should be fairly easy for them.”
Homeowners off of 20th Street SE and on Ebey Island will have to take more circuitous detours to get on and off the trestle, using surface streets off U.S. 2 or Highway 204, Ahmadi said.
The westbound exit to Home Acres Road and Ebey Island was closed Tuesday and won’t reopen until October. The eastbound exit will close from 6 p.m. to 6 a.m. on nights when the westbound trestle is closed.
The concrete girders used to make the bridge in 1968 were built in a way that allowed water to reach the steel rebar that holds the concrete together, said Ralph Dornsife, a state bridge engineer.
Over time, that water has caused the steel to corrode, chewing into the concrete surrounding it. Workers need to remove all the loose concrete pieces and scrape clean what’s left of the rebar.
The rebar will be sandblasted and painted with a corrosion inhibitor, he said.
Then, by hand trowel, the girders will be contoured into their original shape.
Finally, the same carbon fiber used to build Boeing’s new 787 passenger jet will be glued to the reshaped concrete, locking it in place.
“The carbon will take the place of the steel that has been lost,” he said.
Carbon fiber is 10 times stronger than steel – so strong that the trestle could easily continue moving traffic for another 30 years, Dornsife said.
About 300 feet of trestle outfitted with the material eight years ago is showing no signs of wear, he said.
A second, smaller crumbling concrete section of the trestle – from 50th Avenue SE to 43rd Avenue SE – isn’t scheduled for repair until 2011.
Reporter Lukas Velush: 425-339-3449 or lvelush@heraldnet.com.
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