Golden Gate Needs Extra Rust Repairs
Extensive corrosion found this month on the Golden Gate Bridge will require more immediate repairs and extra funding for the current seismic retrofitting contract.
The recent, routine inspection of the structural steel elements was conducted in connection with the ongoing design of the bridge's seismic retrofit.
Corrosion was found on two sets of wind-locks, on both the north and south towers. Located underneath the bridge's roadway, the box-shaped steel wind-locks are made of vertical plates and horizontal lacing bars and transfer lateral forces caused by wind and seismic events from the span to the towers.
The Golden Gate Bridge conducts constant inspections, but a spokesperson for the bridge's Highway and Transportation District could not immediately confirm exactly when the wind-locks were last inspected.
The district's Finance-Auditing Committee is scheduled to meet on Friday, Jan. 25 to authorize a $475,000 budget increase for the repairs.
Repairs Require Complex Access
The district engineer asked the design consultant already working on the seismic retrofit project to perform a structural analysis and design of the wind-lock repairs and develop the construction drawings and specifications for the repairs.
Repairs will involve the following:
According to the engineering staff's report, the most cost-effective, timely way to perform the work is under a contract change order to the current contract with North Anchorage Housing and North Pylon for ongoing seismic retrofit work.
Establishing a separate construction contract for the wind-lock repairs would delay the work by eight to 10 months while the district advertised, awarded and mobilized each contract, the report said.
By using the same contractor, work will already be coordinated with existing construction, and the contractor already understand the complexity of the project, which the report says involves "substantial amount of structural steel fabrication and erection" and requires "precise measurements and investigations of existing conditions, installing of complex access systems, and adherence to detailed work plans."
Utilizing the existing contractor will eliminate the cost of the learning curve that new contractor would have.
Additionally, changing the contract to include the wind-lock repairs will allow for the same lane closures already planned through the late spring.
The report said that the engineering staff and contractor have negotiated a price of $375,000 for labor, equipment and materials. The remaining $100,000 will fund analysis and design, district labor, and other items.
The district has already received the go-ahead for the contract change from the FHWA and Caltrans, with the understanding that the cost of the wind-lock repairs is not eligible for federal funds and will be funded from district reserves.