The Zipper That Tamed Head-On Death
A 3,500-ton moveable concrete barrier finally ended decades of fatal head-on collisions on the bridge's undivided roadway.
Mariordo (Mario Roberto Durán Ortiz) / CC BY-SA 4.0
This is the single most significant safety feature added to the Golden Gate Bridge since the day it opened.
— Denis Mulligan
The Road Zipper System: A Safety Milestone for the Golden Gate Bridge
In 2015, the Golden Gate Bridge underwent a critical safety enhancement with the installation of the Road Zipper system, a moveable median barrier designed to prevent head-on collisions.
What happened: Between 1970 and 2014, the Golden Gate Bridge experienced 16 fatal head-on collisions due to the lack of a physical median barrier. To address this issue, Denis Mulligan of Lindsay Construction led the project to install a $30 million Road Zipper system. This innovative solution involved a transfer machine that could shift 3,500 tons of concrete barrier segments, effectively creating a physical separation between opposing traffic lanes. Wikipedia and Golden Gate Bridge Highway and Transportation District provide detailed information on the project.
Why it matters: The Road Zipper system not only eliminated head-on crossover crashes but also allowed for flexible lane configurations during rush hour, accommodating varying traffic demands. This milestone significantly improved the safety of the Golden Gate Bridge, one of the most internationally recognized symbols of San Francisco and California.
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Why This Mattered
For decades, the Golden Gate Bridge had no physical median barrier — just plastic pylons separating opposing traffic on six lanes. Over 16 fatal head-on collisions occurred between 1970 and 2014. The $30 million Road Zipper system, using a transfer machine to shift 3,500 tons of concrete barrier segments, eliminated head-on crossover crashes entirely while still allowing flexible lane configurations for rush-hour traffic.
