Problems continue to plague the rebuilt eastern section of the iconic San Francisco-Oakland Bay Bridge, with internal leaks continuing amidst recent storms despite the use of caulking to remedy the problem.
Internal leaks caused by the bolt holes for guard rails in the completed US$6.5 billion bridge section were first detected last winter. This prompted the Bay Area Toll Authority to caulk around 900 of the holes in a bid to plug the leakages.
The caulking proved inadequate during a recent slew of stormy weather, however, with water accumulating within the splay chambers – sealed rooms that play a critical role in securing the main bridge cable to the new span.
It’s of paramount importance that splay chambers be kept dry in order to prevent the corrosion of the anchor rods attaching the main cable to the span.
“You obviously don’t want water in the splay chambers,” said Andrew Fremier, deputy executive director of the Bay Area Toll Authority.
According to Fremier, despite the ongoing leakages, the use of dehumidifiers has kept moisture levels within the splay chambers within acceptable levels. The California Department of Transportation (Caltrans) has measured humidity within the rooms at 38 per cent – just below the 40 per cent threshold at which corrosion begins.
Leakages and corrosion problems have long been concerns for the rebuilt eastern section of the Bay Bridge, which opened on September 2, 2013 at a reported cost of over US$6.5 billion, and according to Guinness World Records is currently the world’s widest bridge.
Bill Casey, a senior Caltrans engineer for the eastern section, said the chambers were severely affected by water during the construction process for roughly a year, from December 2011 to December 2012.
Humidity levels within the splay chambers surged last winter as a result of the leaky bolt holes, causing puddles to form during stormy weather at a time when the dehumidification system was not yet properly operating.
According to news reports in April 2014, two types of corrosion were evident within one of the splay chambers – the white rust produced by a protective layer of zinc, and the reddish-brown rust of the underlying steel.
This rust creates significant risk for the integrity of the bridge as it makes the cable strands and rods susceptible to cracking – particularly given the constant vibrations caused by heavy traffic traversing overhead.
In response to these reports, officials planned to caulk all the leaks prior to the start of northern California’s rainy season.
Fremier said Caltrans engineers had informed him of their failure to properly complete the task, while blaming the leaks on design problems.
According to Fremier, Caltrans will refrain, however, from seeking compensation for these problems from bridge designers TY Lin International and Moffant & Nichol, and will consider the plugging of the leaks to be a repair and maintenance issue.
Caltrans spokeswoman Leah Robinson-Leach said that despite the potential problems caused by corrosion it will be impossible to completely solve the problem of leakages during severe weather conditions.
“There will always be some type of water presence after storms like those,” Robinson-Leach said. “(The bridge) never was and never will be waterproof.”