Are Our Bridges Safe to Drive Over?

Chris d Craiker ALA/NCARB

One year ago, the Francis Scott Key Bridge across the Patapsco River at Baltimore, Maryland, collapsed as a monster cargo ship plowed uncontrolled into it. On the same anniversary, the National Transportation Safety Board, NTSB, issued a preliminary report that 68 national bridges are at risk of collapse by vessel strikes. The incident and the report have sent shivers up and down every Bay Area commuter crossing our bridges, particularly those using the Golden Gate Bridge and the San Rafael-Richmond Bridges, the major North Bay links with the rest of the Bay Area. In addition, it is estimated that over 75 % of all Napa, Sonoma and Marin goods arrive via those two bridges. In the case of the Baltimore Bridge, a proper risk assessment could have alerted Maryland officials to the bridge’s vulnerabilities, but nothing was conducted.

The Chair of the NTSB, Jennifer Homendy, noted the collapse probably could have been prevented had the proper assessment and prevention strategy been created. The bottom line is this bridge, and the others have been ignoring potential catastrophic damage by increased ocean traffic and by not coping with the new colossal container ships.

The award-winning San Francisco architect Donald McDonald is currently working on new fenders to protect the Baltimore Bridge as it gets rebuilt. McDonald was the first architect to work on the Golden Gate Bridge since its original construction and is the architect for the Bay Bridge Western portion with the singular tower and distinctive lights. In an interview with McDonald, he described the proposed fenders protection required for the Baltimore Bridge as a block of concrete almost a 374 feet long and 218 feet wide with piers 25 feet on center going down as far as 300 feet.

“The biggest single problem today is that these bridges are getting older without sufficient maintenance or tower protection as the ships get bigger and bulkier every day,” MacDonald said. “In San Francisco, the Golden Gate Bridge usually has a tugboat that goes along with incoming large cargo or oil container ships, but not always.”

In the case of the Golden Gate Bridge, over 100,000 vehicles crossed the bridge every day. It's been designed to withstand earthquakes, strong winds, swift tides and it continues to perform well linking San Francisco and the North Bay counties while guarding the entrance to the San Francisco Bay. On the list of vulnerable bridges besides the Golden Gate, there are the Richmond-San Rafael, Carquinez, Benicia- Martinez, Antioch and San Mateo-Hayward Bridges among the 68 that have a potentially risk of collapse from a vessel collision similar to the Baltimore disaster. While slim, the risk has a lot to do with the size of ships that can navigate beneath them. The further from deep water traffic, the safer. Thus, the Richmond-San Rafael has less of a risk than the Golden Gate.

The National Bridge Inspection Standards, NBIS, has a database of over 623,000 bridges and culverts over 20 feet long nationwide and compiles records from each state. Federal regulations are simple: they are either Good, Fair or Poor. Data suggests that 51% of all bridges in America fall into the Fair category. The NBIS uses inspection reports provided every two years by each State. California has approximately 10% of its bridges in Poor condition, 40% in Fair while approximately 50% of the State’s bridges fall into the Good category.

Interestingly, of the 20 busiest bridges in America the Bay Bridge has the second highest likelihood of a large ship collision while the Golden Gate has the second lowest. Nonetheless, for the Golden Gate Bridge there is evidence of the need for a major fender to protect the South Tower. The North Tower is very close to the Marin embankment and is considered outside of a potential disaster.

According to the Golden Gate Highway Transportation District, the Golden Gate Bridge has the most robust ship collision protection of any bridge on the West Coast. The South Tower, which is anchored to bedrock beneath the water, is protected by a concrete fender ring extending 40 feet deep, the same depth drawn by a large ship. The concrete fender is filled with sand, similar to a highway crash barrel, and is 27 feet thick at its base to provide collision protection.

Is the North Bay at risk of a connectivity disaster with our sister counties? Only if container ships continue to get bigger and are allowed through the Golden Gate. The Dali that hit the Francis Scott Key Bridge was 95,000 tons,984 feet long and 157 feet wide. Currently, the world's largest container ships are over 40% bigger with capacities up to 234,000 tons, 250% larger. Those are colossal ships! If anything, there should be restrictions on the size and capacity of these vessels. Restricting vessel volumes would be a better strategy than building bigger fenders.

Chris d Craiker ALA/NCARB