RICHMOND (CBS SF) — Drivers on the westbound upper deck of the Richmond-San Rafael bridge will see sparks flying for several months as highway work crews replace dozens of expansion joints, one of which failed last month and dropped concrete on top of vehicles below.

Caltrans work crews are using jackhammers and blowtorches along with heavy equipment to demolish the existing joints and replace them with new ones.

On February 7, an expansion joint broke apart on the upper deck, sending chunks of concrete down onto cars on the lower deck of the bridge. Luckily nobody was hurt, but it caused a major traffic jam for the better part of a day, diverting commuters through wine country.

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Only one joint was broken, and they fixed it. Then Caltrans engineers found dozens more had some wear and tear. So now they have decided to replace all the joints that date back to the 1950s.

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“As a precaution, there’s about 62, 63 of these on the bridge that we decided as a risk assessment, we’re going to replace these joints now,” said Tony Tavares, CALTRANS District 4 Director.

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While the work is taking place, the Richmond-San Rafael bridge will be closed form 9 p.m. to 5 p.m. every night. Tavares said the project should take about three months. Later this year, Caltrans will begin a similar 3 month project to replace the joints on the lower deck.