An update on the Devil's Slide bridge

June 5, 2008 6:46:20 PM PDT
The finishing touches are being put on a bridge that will one day link Peninsula commuters to a smoother ride along Devil's Slide.

The bridge linking Highway 1 with the new Devil's Slide tunnel has been under construction for about two years now. And on Thursday, the last section of concrete on the bridge is being poured.

Just south of Pacifica, two bridges now stand side-by-side. In the coming years, they will link Highway 1 with the Devil's Slide Tunnel.

"I'd say we're about 95 percent complete," said Caltran engineer Cliff Law.

The bridges have been constructed one segment at a time, marching out from either side to meet in the middle.

"We didn't miss it by much, we're off by millimeters," said Law.

Law says one side of this bridge is 20 millimeters higher than the other, so four 9,600-pound concrete slabs were set on it to push it down before they link the two sides.

A final concrete pour is happening in the afternoon instead of the morning because the sunshine makes the already dry concrete on the existing sides of the bridge curl.

"These large cantilevers, when the sun hits the top of the deck, they heat up and they expand and they tend to curl down. And you don't want it to be moving when concrete's trying to cure because it'll crack the concrete," said Caltrans engineer Sergio Gomez.

The bridge is hollow, but this is a part of the structure motorists will never see.

Inside the bridge, some tubes are an investment for possible use in the future. If Caltrans finds that in 10 or 15 years the bridge is sagging more than it should, tensioning cables can be run through here, to pop the bridge up.

Javier Chavez is the bridge architect. He says he was inspired by the curving hillsides and sloping valley of the site.

"We designed a nice-looking bridge in a nice looking location and everybody's happy," said Javier Chavez.

All the details should be wrapped-up by the end of July. Then the tunneling contractor will start digging on the other side, and meet up with workers already digging from the south.


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