A little concrete was added to one of the world’s signature steel structures earlier this year as Golden Gate Bridge engineers effected a major safety upgrade for northbound (Marin County) and southbound (San Francisco) drivers: Installation of a 13,330-ft. Barrier Systems median structure.
|The Golden Gate Moveable Median Barriers were staged in San Francisco, near the south approach. The 3,500 MMB were produced in two phases between Lindsay Transportation Solutions plants in Nebraska and California: Galvanized steel shells and pin connectors fabricated in Omaha and shipped to Rio Vista, home to the Barriers Systems brand, then filled with Cemex-supplied concrete and prepped for delivery to the Golden Gate site.|
A division of Omaha-based Lindsay Corp., Lindsay Transportation Solutions has delivered Barrier Systems’ flagship Quickchange Moveable Concrete Barrier (QMCB) and companion Road Zipper transfer vehicles worldwide for flexible traffic lane management. In contrast to the legacy Jersey concrete barrier, with flush, tapered top, the precast QMCB has a T-shaped cap enabling Road Zipper lifting and lateral relay—mimicking a sidewinder.
A streamlined version developed for the Golden Gate Bridge, Highway & Transportation District combines a galvanized steel shell and concrete filling, 32-in. high, with 12-in. top width and 24-in. base, plus pin connector linking. Dubbed Moveable Median Barrier (MMB) and slightly narrower than the QMCB, it was specified after nearly two decades of engineering and review as the District sought a safe, robust solution to virtually eliminate crossover collisions between outbound (north) and inbound (south) drivers. Late in the review, the MMB concept passed muster when subjected to wind tunnel testing, an essential regimen for any Golden Gate Bridge modification. District engineers confirmed that more than 2.5 miles of MMB would not negatively impact to the span’s wind dynamics.
Prior to the MMB deployment, the agency used 19-in. tall, 4-in. plastic tubes, spaced at 25-ft. intervals—reconfiguring lanes throughout the day based on real-time traffic volumes. The District estimates a $30.3 million initial MMB investment, funded by primarily by the State of California through the Metropolitan Transportation Commission, plus bridge toll revenues and a minor federal contribution.
|The newest specialty vehicle in the Golden Gate Bridge Transportation District fleet is the Lindsay Road Zipper, which transfers barriers at a typical pace of 704 – 880 feet per minute (8-10 miles per hour). District officials estimate typical XX-minute cycles for median barrier movement across the 1.7-mile Golden Gate zones.|