The roadway was closed on Wednesday, Nov. 28, and Sunday, Dec. 2, after a series of storms dumped several inches of rain in the Bay Area, caused power outages and felled trees, making a mess of roadways and causing traffic delays throughout the region. On Sunday, a tow truck had to remove a car that stalled in the water and was immersed up to its hood.
On Dec. 5, another storm filled the underpass with several inches of water at the height of the morning commute. The roadway wasn't shut down, according to Palo Alto police, but drivers headed west veered into the less-flooded left lane to avoid the deep water.
The Oregon Expressway underpass is under the jurisdiction of the Santa Clara County Roads and Airports Department, according to Linda Clerkson, a city spokeswoman. The county was notified by the city Dec. 5 morning about condition at the underpass, she said.
Because the roadway is sunken, water collects in it and must be pumped out. Pumps detect when the water reaches a certain level and turn on to divert the water to the nearby creek.
Dan Collen, deputy director of county Roads and Airports, said the Nov. 28 flooding incident was due to human error. A worker incorrectly set equipment that controls the drainage.
Wednesday's flooding was caused by an electrical-equipment failure. Crews rebooted the computer and tested the equipment to make sure it was running properly again. But workers discovered that a circuit that tells the pumps to start working needs to be replaced. Collen said repairs should be completed by Thursday or Friday. He said the water was pumped out by 9:30 a.m.
Flooding at the underpass has been a problem during other large storms. Oregon Expressway was closed due to flooding in January 2008, and one lane of Oregon was closed due to 5 to 7 inches of water in October 2009.
The underpass is not part of a county plan to improve Oregon Expressway from West Bayshore Road to Bryant Street, which is designed to improve traffic flow. Collen said funding is in place for that work, and the plans are ready to go. The Roads and Airports Department is awaiting an environmental clearance from Caltrans so that work can begin.