When the motor conked out Friday on one of the massive construction cranes, it presented the bridge builder with a towering problem.
The 3,000-pound motor needs to be replaced, meaning Tacoma Narrows Constructors has to get it down from its perch on top of the crane, 40 stories above The Narrows.
After giving serious consideration to hiring a heavy-lift helicopter, TNC instead decided to lower the motor with a portable winch.
“We figured that would be less of a distraction to drivers on the bridge,” said TNC representative Erin Babbo.
A special five-person crew will scale the tower crane today, wrap the big electric motor in a sling and lower it to a work barge on the water.
The 175-horsepower, Swedish-made Liebherr motor ran the main hoist on the tower crane on the Tacoma side of the bridge. Babbo said the bearings inside the motor failed.
The big crane, and another like it on the Gig Harbor side of the bridge, lift all the steel rebar used in the construction of the tower. They also lift all the concrete, hoisting it in a 4-cubic-yard bucket. When finished, each tower will contain 8,000 cubic yards of concrete.
A replacement motor, which TNC located in Orting, will be winched to the top of the crane later this week, Babbo said.
The motor failure will set the bridge builder back five days, but TNC says it will make it up the time in other phases of construction.
The two bridge towers, which will top out at 510 feet, are scheduled to be finished next spring.
Rob Carson: 253-597-8693