SAN FRANCISCO » The Golden Gate Bridge has reopened to traffic following a weekend-long closure so workers can install a moveable median barrier.

A spokeswoman for the Golden Gate Bridge Highway and Transportation District says the bridge opened at 9:30 p.m. Sunday, six hours ahead the target hour of 4 a.m. Monday.

Officials shut the bridge to all but pedestrians, cyclists and buses starting early Saturday to install the barriers, which are designed to prevent head-on collisions on the 1.7-mile-long bridge.

The weekend closure was the longest in the bridge’s history and the first since 1987, when the bridge shut for a few hours for a celebration of the 50th anniversary of its construction.