UPDATE Caltrans to remove ceiling material in Tubes
UPDATE: The start of construction has been pushed off to Sunday night.
Caltrans begins work tonight Sunday night to remove portions of the ceiling overlay of the Posey and Webster tubes. Construction is expected to continue through August.
“This project was developed after a review by Caltrans Structural Maintenance and Investigations. Inspectors determined that some portions of the fiber reinforced concrete on the ceiling (were) not bonding properly. A project was developed to remove that material,” Caltrans spokesman Allyn Amsk said.
Crews will remove a 23-foot-by-80-foot swath from the Webster Tube and a 23-foot-by-550-foot stretch from the Posey Tube.
The work follows the collapse of an eight-foot-by-eight-foot section of the fiber-reinforced concrete overlay into the roadway of the Webster Tube in January 2009, which prompted inspectors to scan both tubes and to remove an additional 24-foot-by-20-foot chunk of concrete from the Webster Tube the following month.
At that time, they said the inch-thick slab was removed because inspectors discovered it was “delaminating,” or not sticking well in some places. But Caltrans insisted the tubes were safe, and Amsk said the concrete has held since.
“It’s held. It’s been okay,” Amsk said.
Construction will begin in the Webster Tube, and will take place from 11:30 p.m. Sunday to 4:30 a.m. Monday and 10:30 p.m. through 4:30 a.m. Monday night through Friday morning. Once work is completed in the Webster Tube, crews will move on to the Posey Tube.
Caltrans will detour traffic on and off the Island to the Park Street Bridge during construction.
Amsk said in February 2009 that the concrete is cosmetic and was placed in the tubes’ ceiling in 2004. He said it was laid in place of tiles removed during a retrofit of the tubes.
The work is being done by Disney Construction of Burlingame, and the contract amount is $269,333.