The Murray Morgan Bridge is closing this weekend.
A contractor “discovered an issue” with the ongoing seismic bracing work, according to a city news release. Crews will also replace the bearings on the Port approach pier that were previously delayed.
The bridge will be closed from
6 a.m. 9 p.m. Thursday to 6 a.m. Monday. Boats can still pass below with a two-hour notification.
UPDATE, 3:55 p.m. from reporter Kathleen Cooper:
The “issue” is that the bridge isn’t balanced, a city project manager told me.
“We’re trying to operate the bridge in a perfectly balanced condition, so that the weight of the lift span is equaled by the weight of the counterweights,” said Tom Rutherford, project manager for the City of Tacoma.
Having the bridge in balance means the 150-horse-power motor that lifts the span can work as efficiently as possible, he said.
The bridge has to close because large cranes are required to do the work, and they block the entire road. The cranes will remove large steel plates from the top of the two counterweights, each of which now weighs a little more than they should.
The lift span weighs about 2 million pounds, Rutherford said, so the two counterweights should equal that. Right now the counterweights together are about 24,000 pounds too heavy.
One the weight is removed, workers must reinstall the scales and stress gauges that measure whether the bridge is in balance. No traffic can be on the span at that time. Workers also will be replacing some bearings on the port approach pier.
The bridge officially reopened Feb. 15 after a $57.4 million renovation. It had been closed to traffic since 2007.
Rutherford said the bridge balance was measured before its grand re-opening.
“But we were still doing a little work out there, adding a few things, taking a few things off, and we realized it may be off,” he said. “I’m not shocked that it’s happened. We were hoping that we’d come out right on, and considering we have to take off just 24,000 out of the amount that’s up there, we were pretty close.”