Looking for a Lifeline
Will the Big One Take Out Alameda’s Bridges?
Nearly 74,000 people lay their heads down in the Island City. Most of the employed leave in the morning by bridge, tube or ferry, but some are among the 22,283 who work for Alameda’s 2,900 businesses. And in the event of a major earthquake, they could all quickly become stranded on one side or the other of the inner harbor.
The city, county and state have collabo-rated over the last almost dozen years to reinforce this critical link in Alameda’s transportation infrastructure, but financial constraints have left the city without “lifeline” access on or off the island. For a bridge, tunnel or tube to meet state lifeline standards, it must be able to be made functional within a couple days of an earthquake of maximum credible size, in Alameda’s case a magnitude 7.25.
Instead, all of Alameda’s major bridges and tubes are rated at the lower “no-collapse” level. This means that in a quake of that magnitude, they’re designed to do just that: not collapse, as a portion of the upper deck of the Bay Bridge did in the 1989 Loma Prieta earthquake. However, one or all could be damaged significantly enough to require months or years of repair, or perhaps the eventual construction of a total replacement.
“ ‘No collapse’ doesn’t guarantee that it’d be functional,” says Art Carrera, principal civil engineer for the Public Works Agency of Alameda County. “The intention is to save lives.” Over the past couple of years the county has completed retrofits of both the High and Park street bridges, bringing them up to no-collapse status, and is in the midst of doing the same for the Miller-Sweeny Bridge on Fruitvale Avenue, a project that should be complete this month.
The total cost of the retrofits will be around $2.2 million, covered in part by federal and state funds. But what the city and county really wanted — to upgrade the Miller-Sweeny Bridge to a lifeline facility, ensuring access on and off the island in the days following a major earthquake — comes at a much greater expense. This would entail the construction of a brand new bridge and cost at least $40 million, a sum that the county has been chasing since 2003.
Without a guarantee that the money for a new lifeline bridge would ever become available, the county Public Works Agency decided to spend half a million dollars retrofitting Miller-Sweeny, which was previously identified as the city’s best candidate for a lifeline upgrade. But that doesn’t mean Alameda has given up hope.
In fact, in 2011 the city set its sights far beyond the county’s $40 million bare-bones Miller-Sweeny rebuild, which still sits on Alameda County Transportation Authority wish-lists. The city’s proposed $94 million plan would not just strengthen, but significantly enhance the design of the existing bridge by incorporating a bus lane, bike lane, sidewalk and the current separated railroad bridge into a single structure.
Carrera sees Alameda’s vision as a bit of a luxury. “Our priority is the lifeline, but if they want other features, we would support them in that effort,” he says. “But to go from a $40 million project, which has already been hard to get, up to $94 million, is a
Caltrans, meanwhile, has played its own part in improving, if not necessarily securing, the safety of transportation on and off the Island. In 1997, it retrofitted the Bay Farm Island Bridge, which spans the San Leandro Bay, to no-collapse status. And between 2000 and 2003, it did the same for both the Posey and Webster Street tubes, despite calls among city leaders for a lifeline retrofit. According to CalTrans spokesperson Bob Haus, this was the first time a submerged freeway tube had ever been earthquake-retrofitted.
The work involved driving columns of concrete, steel and rock into the land flanking the tubes to reduce the effects of liquefaction, where saturated soil loses stiffness and begins to act like a liquid as the result of an earthquake. Liquefaction is possible throughout Alameda’s perimeter and northern half, where much of the landmass is fill instead of more stable Merritt Sand, but liquefaction presented a particularly high risk around the underground tubes.
“During liquefaction, the soil becomes very muddy, and there could be enough air introduced into the soil that the tubes could become buoyant,” explains Haus. “So this ensures that the tubes will stay put.”
Yet even in conjunction with new, bulkier steel joints, it isn’t enough to guarantee that the tubes will be usable within days of a major seismic event. This leaves one final option for transportation on and off the Island: ferries. And that is where the city now places its faith. “For Alameda, the ferries function as our lifeline,” says city of Alameda Public Works Director Matthew Naclerio.
The San Francisco-based Water Emergency Transportation Authority, mandated by the state to coordinate both public and private ferry response to emergencies, would make Alameda a regional priority in the case of a big quake, says manager of operations Keith Stahnke. “There are few other communities that would be affected as much as Alameda would.”
The organization has plans to move its maintenance and mooring facility from San Francisco to Alameda Point, which would make ferry transport more accessible to Alameda residents immediately following an emergency. There’s also the possibility of adding additional ferry service to the Alameda Point seaplane lagoon, Stahnke says, whenever development occurs at the former Alameda Naval Air Station.
But none of this would quite make up for the lack of a functioning bridge or tube, which could transport not only individuals and passenger cars but also emergency vehicles and large trucks containing supplies. The Alameda County Transportation Commission continues working to secure local or federal funds for a new Miller-Sweeny bridge, but even in a best-case scenario, it could be a decade or more before Alameda finally gets its lifeline.