Bridge improvements that were considered urgent almost a decade ago now might not begin until 2023, city officials say.
“We are caught in a unique situation with changing rules and regulations that were not anticipated,” said Public Works Director John Doughty.
The bridge was built in 1890, and was one of the first reinforced bridges in San Mateo County.
“They used cables left over from the cable cars in San Francisco inside the bridge. They did not provide much structural value, but it was considered state of the art,” said Ray Razavi, the city’s transportation engineer.
The bridge serves as an entry point to downtown Half Moon Bay from Highway 92 and sits over Pilarcitos Creek. After normal wear and tear and at least two major earthquakes, Caltrans, in 2010, deemed the bridge in need of immediate repair. A Caltrans assessment of the bridge yielded a sufficiency rating of 27 out of 100.
“Its score started dropping because it did not meet the seismic standards. It started showing cracks. So from just a visual perspective, it did not look good,” Doughty said.
At that point, discussions centered on a complete tear down and construction of the bridge. Some residents expressed concerns over losing the city’s historic bridge while others were worried the construction would impact local businesses and traffic flow.
“The city pulled back from moving forward, primarily because there was an initiative that went to the voters that was then followed by an assessment,” Doughty said.
Up until 2015, the city had no technical assessment of the bridge other than the Caltrans work. The city hired a private engineering service, based in Colorado, to do its own assessment of the bridge.
That report from 2015 concluded, “The bridge is structurally sound, but restoration and rehabilitation is needed to retain and enhance structural integrity into the future.”
The study did note that the bridge did not meet seismic standards.
Meanwhile, Caltrans changed its grading system and re-evaluated the bridge with a higher score. The state transportation agency now considers it eligible for rehabilitation rather than demolition.
By 2016, the city proceeded with obtaining federal bridge funding to “ensure the historic bridge will remain in place for the long haul,” Doughty said.
“In simplest terms, under normal conditions, the bridge is structurally sound and not a threat to public safety,” he said.
However, the bridge is located in an area of high potential liquefaction and there is no guarantee of stability in a future major earthquake.
Earlier last year, the City Council entered into a $1.1 million contract with Biggs Cardosa Associates Inc. to work on the design phase of the project. While still in early stages, the project hit a delay after Caltrans and the federal government set new standards for acceptable barriers to use when repairing a bridge.
The bridge today is flanked at either end with white pilasters that feature a cap on top. Under current federal guidelines, the city would not be allowed to keep those as part of the rehabilitation process.
Doughty explained that the pilasters were added to the bridge sometime in the 1930s. At the July 16 Half Moon Bay City Council meeting, elected officials will be asked to approve design work incorporating the federally approved barrier, which is concrete that can be painted white.
“The big question is, are we OK with going back to this earlier version of the bridge?” Doughty said. Once construction starts, the project will include putting in a new foundation, pouring new wing walls and creating a new sidewalk bridge that is ADA compliant.
The project is expected to cost $8.5 million with about $7.5 million coming from federal funding.
Razavi said construction is expected to start in 2023.
“It’s not the Golden Gate Bridge, from a fashion standpoint, but the top of the bridge and the roadway will be pretty functional,” said Brian Douglas, a Half Moon Bay resident and chair of the Main Street Bridge Advisory Committee.