Work crews prepare for this weekend's demolition of part of the Mulholland… (Al Seib / Los Angeles Times )
If demolition work on the Mulholland Drive bridge goes smoothly this weekend, the 10-mile section of the 405 Freeway might reopen early, though officials said Thursday they did not know how much sooner traffic could be moving again on one of the nation's busiest interstates.
All ramps, freeway connectors and lanes on the 405 are set to be back in operation by 6 a.m. Monday. Officials said the freeway could reopen earlier if contractor Kiewit Infrastructure West Co. can finish and clean up the pavement ahead of schedule.
"We don't know if we will be able to do it or when," said Dan Kulka, a community relations manager for Kiewit. "We will keep our eye on this throughout the weekend. Come Sunday afternoon or evening, we should have a good idea what we can do."
The 405, which handles an average of 281,000 vehicles per day, is scheduled to be shut down for about 53 hours from the 10 Freeway to the 101 Freeway on the northbound side and from the 101 Freeway to Getty Center Drive on the southbound side.
The closure is designed to give construction workers enough time to raze the southern half of the bridge, which will be chipped away using cutting saws, acetylene torches and jackhammers mounted on heavy equipment. About 4,000 tons of concrete must be removed.
"They have a lot of work to do," said Dave Sotero, a spokesman for the L.A. County Metropolitan Transportation Authority. "The contractor will look for opportunities to expedite the schedule."
Sotero cautioned that people should not expect the 405 to be back in operation sooner than scheduled because unexpected problems could arise.
Motorists traveling through the Sepulveda Pass will see the first signs of the closure about 7 p.m. Friday, when the California Department of Transportation and the California Highway Patrol start shutting down on-ramps.
The closures will begin at the 101 Freeway and proceed to Getty Center Drive on the southbound side and to the 10 Freeway on the northbound side. All on-ramps should be closed by 9 p.m.
About an hour later, the freeway connectors linking the 405 to the 101 and the 10 will be shut down.
Also at 10 p.m., workers will begin the process of gradually closing lanes on both sides of the freeway, starting with the carpool lanes.
They will finish with the slow lanes about midnight, the same time that all the off-ramps will be closed. Barricades also will be erected where the off-ramps connect with surface streets.
Should motorists approach the closure area, they will be channeled from the 405 onto the 101 Freeway or the 10 Freeway. Those traveling on the 101 and the 10 will not be able to enter the 405 because of the closed connectors.
The freeway will be blocked in both directions by red cones and so-called attenuator trucks with crash cushions in front. Signs and portable message boards with directional arrows will help guide motorists.
If the 405 is not reopened early, all lanes and freeway connectors are scheduled to be back in operation by 5 a.m. Monday. The on- and off-ramps will be returned to service by 6 a.m.
Transportation officials said that Sepulveda Boulevard will remain open during the demolition work. The heavily-traveled street parallels the 405 and provides an alternative link between the San Fernando Valley and West L.A.
Though difficult to enforce, officials have advised motorists who don't live in the area to use other routes to reach their destinations instead of Sepulveda and other major streets that connect the Valley and West L.A.