Thanks to an innovative $30 million moveable median barrier, completed in January 2015, head-on collisions on the Golden Gate Bridge are a thing of the past, and driving is a lot safer for the 2.5 million vehicles per month that cross the iconic 1.7-mile span.
The barrier is a mechanical “zipper” that changes the configuration of the bridge’s six lanes twice daily to keep traffic flowing smoothly.
The barrier consists of 3,200 concrete median units, each weighing 1,500 pounds, linked together to form a semi-rigid barrier. It takes a 30-ton, 58-foot long transfer machine (aka zipper truck) to shift the new barrier. As the giant machine moves over a barrier unit, the segment is lifted up and moved to the other side of the lane. Previously, the bridge used much flimsier pylons to separate the directions of traffic, with crews manually placing and pulling pylons while traveling along slowly in a truck.
The weekend operation to install the new median barrier went without a hitch. The bridge was shut down at 11 p.m. on Friday, January 9, 2015, and reopened on Saturday, January 10, with the contractor Ghilotti Bros., Inc. completing the job 12 hours ahead of schedule. Drivers easily adapted to the new barrier, and the system has functioned smoothly ever since.
