SAN FRANCISCO commuters are involved in a last ditch attempt to have a heavy rail line included in designs for the new £395M east span of the planned Oakland Bay road crossing before construction starts next year.
They believe that building a new crossing for heavy rail as well as road traffic will be cheaper than building a separate rail crossing, possibly in tunnel.
Although new immersed tube and bridge crossings for commuter rail lines have been proposed, the estimated construction cost - between £3.5bn and £7bn - makes adapting the new link the cheapest option.
Oakland, San Francisco, and the neighbouring metropolitan centres of San Jose and San Mateo Redwood City, recently commissioned a report from consultant Arup on the feasibility of putting commuter rail across the Bay Bridge.
The cost of including heavy rail in the new structure after construction is estimated at £340M according to Arup.
The east span, linking a viaduct from the Oakland shoreline with Yerba Buena island enroute to San Francisco, is being built to replace the existing double deck steel truss crossing, damaged in the 1989 earthquake.
Seismic strengthening of the west span is already under way.
Pushing the east span project forward is regarded as a matter of urgency, said manager of bridge and highway operations at the Metropolitan Transportation Commission for San Francisco, Rod McMillan. Detailed design is now 85% complete and tenders for construction will be invited later this year.
Although the bridge is likely take road traffic only when it opens in 2006 it is designed to carry four-car light rail trains.
However, transport lobbyists and politicians see commuter trains with 10 cars as a means of easing congestion.
But McMillan said California transport authority Caltrans and the MTC will not revise designs for higher loading at this stage.
This means that major strengthening of the east span will be required should commuter rail be introduced in the future.