Golden Gate Bridge Zipper

See that bright yellow vehicle on the Golden Gate Bridge? That’s the zipper truck — an ingenious machine that keeps nearly 100,000 cars per day moving safely across the span to and from San Francisco.

Before the movable median barrier was installed in January 2015, the bridge averaged about 40 head-on collisions per year — more than 1,000 total since the bridge opened in 1937. Following the system’s installation, there have been zero fatal head-on crashes.

The zipper truck works by lifting and shifting linked steel-and-concrete blocks that form the center divider. Each individual block weighs about 1,500 pounds (680 kg). It moves the entire barrier at about 5-10 miles per hour, sliding it up to 24 feet sideways to adjust lane configurations for rush hour traffic.

Each pass takes about 30–40 minutes, and crews usually make two passes per weekday: once in the morning to add more southbound lanes into San Francisco (typically 4 southbound and 2 northbound lanes) and again in the evening to expand northbound lanes for drivers heading back to Marin County (usually 4 northbound and 2 southbound).


Source imagery: Nearmap