SAN FRANCISCO (CBS SF) — Northbound Interstate Highway 280 in San Francisco reopened Monday night following a closure over the Labor Day holiday weekend for a construction project to strengthen the highway in the event of seismic activity, Caltrans officials said.

A portion of the freeway from northbound Highway 280 from the U.S. Highway 101/Highway 280 interchange to San Francisco’s South of Market neighborhood was closed on Thursday afternoon for the project.

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The roadway reopened around 9:45 p.m., about seven hours ahead of schedule.

During the closure, crews replaced hinges on two large sections of the roadway, according to Caltrans officials.

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The highway hinges were designed in the 1960s and an inspection seven years ago determined they were in need of replacement in order to withstand a large earthquake.

Motorists on northbound Highway 280 were detoured to Highway 101 as crews worked on the project.

The highway was also closed for similar seismic strengthening work during the Memorial Day and Fourth of July holiday weekends.

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