Inspection failed to identify cracked concrete
RICHMOND >> An inspection last August failed to identify any obvious problem with cracking in the concrete near a 1950s-era steel joint on the Richmond-San Rafael Bridge, officials said Friday.
Chunks of concrete falling from the bridge Thursday caused some drivers to panic, as pieces as large as footballs fell from the bottom of the upper deck onto the lower deck below, leaving behind a 6-foot-long by 7-inch-wide triangular cavity.
The falling pieces, which tumbled down from the middle of the upper deck near the Richmond side of the bridge, prompted Caltrans to close the roadway for most of the day Thursday. All lanes reopened about 8 p.m., and as of Friday afternoon
there were no new reports of falling concrete, said Tony Tavares, the director of Caltrans District 4, which covers the Bay Area.
It was likely that wear and tear caused the concrete to crack. The cracking occurred near an expansion joint that dates back to the bridge’s original 1956 construction. A heavy truck passing over the joint might have crushed the brittle and aged concrete near the antiquated joint, Tavares said.
He said no work on the bridge would be done over the weekend, and drivers could expect to use the bridge normally. Exact plans for the work still are being drawn up, but Tavares said the work probably would start Monday and take place at night. Repairs are expected to take anywhere from “several days” to “a few weeks,” he said.
But Abolhassan Astaneh-Asl, a professor emeritus of structural engineering at UC Berkeley who served on the advisory committee for the RichmondSan Rafael Bridge when it was undergoing a seismic retrofit in 2005, said opening the bridge so soon would be “a disaster.”
Caltrans shouldn’t open the bridge until the agency can say with certainty the cracks are localized
to only the area where the concrete fell, Astaneh-Asl said. But, he added, without inspecting the entire span where similar conditions exist, there’s no way to know for sure.
“It’s not the safety of the bridge,” he said. “It’s the safety of the drivers.”
But Tavares said the bridge is safe.
“Out of an abundance of caution, our engineers have been on the bridge today continuing inspections and will continue to perform additional inspections of all bridge joints over the coming week,” he said.
“We do not have any concerns with additional expansion joints having any issues at this time,” Tavares said Friday.
But Astaneh-Asl said the fact that the pieces fell from the middle of the deck — as opposed to being caused by a heavy truck driving or parking on the shoulder of the bridge — is a big problem for motorists passing underneath.
“If it’s really widespread, it’s a very serious concern,” he said.
Historically, there have been repeated problems with expansion and deck joints on the Richmond bridge, as well as other bridges with similar joints, said Andrew Fremier, the deputy executive director of operations for the Bay Area Toll Authority, which works with Caltrans to oversee maintenance of the Bay Area’s state-owned toll bridges.
Holes popping up on the bridge prompted $50 million in emergency repairs in 2004, work that was added to the $795 million seismic retrofit, which included replacing 63 concrete deck sections and 700 expansion joints. In early 2006, just four months after the 2005 retrofit work was deemed complete, more holes in the concrete cropped up near joints on the bridge, prompting an additional $25 million in repairs.
In the last five years, the toll authority has shelled out $46 million for various projects on the bridge, mostly joint repairs and painting, said John Goodwin, a spokesman for the authority. It’s also planning another $80 million in ongoing maintenance and replacement of the joints, along with other work, over the next 10 years.
In the short term, Caltrans crews placed steel plates over the affected area, with plywood boards below the deck, to allow motorists to drive over the concrete without more pieces shaking loose and crashing onto the cars and trucks below.
The concrete itself varies in thickness throughout the span but can be up to 10 inches thick. It has a ¾- to 1-inch-thick protective coating that is periodically ground off and replaced. The coating is more durable than the concrete below and has grooves on it to provide better skid resistance and tire adhesion.
Below the surface, however, sections of the concrete date back to the original construction. It’s lightweight concrete, which makes it more prone to breaking off in small chunks, Astaneh-Asl said.
Given the age of the bridge, it shouldn’t be a surprise to see more pieces crumbling off, said Robert Bea, professor emeritus of catastrophic risk management at Berkeley. Age, combined with exposure to salt air, earthquakes, occasional bumps by passing ships and daily traffic, weaken the bridge, he said.
“This process has been going on for a long time,” Bea said, adding that incidents such as the falling concrete motorists encountered Thursday “are not getting less frequent. They’re getting more frequent.”
The bridge has never been a joy for drivers, said Holmann Perez of Fremont. He crosses it nearly every workday to head to his job in San Rafael. He’s never felt comfortable on the bridge’s long, narrow span, he said.
“Who wouldn’t feel nervous?” Perez said. “But there’s no choice when you have to head to work.”
Other commuters opted for a come-what-may approach. Ramona Ortiz-Smith of Woodacre said she just crossed her fingers and hoped no more rocks would fall.
“If they fall, they fall,” she said.