Westbound Simi Freeway Lanes to Reopen : Roads: Last major bottleneck from temblor will be removed this weekend. Eastbound traffic will begin flowing Sept. 7.

To the relief of many traffic-maddened motorists, all five westbound lanes of the Simi Valley Freeway--the last major bottleneck from the Northridge quake--will reopen this weekend, a top state transportation official confirmed Tuesday.

The eastbound lanes will follow Sept. 7, making all 10 lanes available to motorists at the San Fernando Mission Boulevard and Bull Creek overpasses, despite construction delays that once were expected to push the reopening date back to mid-September.

Construction workers, who have toiled around the clock for months, were putting the finishing touches Tuesday on the westbound side of the reconstructed spans, which sagged by as much as four feet in some spots after the quake. Repairs on the eastbound lanes, which now serve as a detour for traffic in both directions, wrapped up in May.

When work shifted to the westbound side, state transportation officials projected it would be completed this week. But a delay in starting and a last-minute tangle over permits to work in the Bull Creek flood-control channel forced the state Department of Transportation to kick back the projected reopening to Sept. 19.

As recently as last week, Caltrans officials held to Sept. 19 as their target date. Nonstop construction and “quite a bit of pressure” from the state, however, spurred the transportation agency and the contractor to try to finish before the heavy traffic loads of the Labor Day weekend, officials said.

Gov. Pete Wilson is expected today to formally announce the reopening, which has been long awaited by many commuters on the northern San Fernando Valley’s chief east-west artery. Since February, the 180,000 motorists who navigate that stretch of the freeway daily have had to squeeze onto a detour, three narrow lanes each way with sharp curves that slowed traffic.

Jana Tanghal, office manager for a Granada Hills insurance agent, said she adjusted her work schedule to avoid the tie-ups that prolonged her drive to work from Thousand Oaks during peak morning hours.

“That way I don’t sit in traffic. I’m tearing my hair out by the time I get here,” said Tanghal, who plans to revert to her pre-earthquake schedule after the freeway is restored.

On Saturday, work crews will open the new westbound bridges, with three lanes available in the early morning and then the full complement of five by noon, officials said. The Woodley Avenue on-ramp and the Hayvenhurst Avenue off-ramp will also reopen.

The contractor, F.C.I. Constructors of San Diego, will then remove the detour from the eastbound side, re-stripe the pavement and open all five eastbound lanes Sept. 7. At that time, workers will reopen the on-ramps at Hayvenhurst Avenue and Balboa Boulevard.

“For people who live close to the Hayvenhurst exit, it’ll be super,” said Sherrill Houston, who lives with his wife just a block away. “It’s going to mean a lot to us.”

Although the contractor is set to finish the $9.6-million project before the Sept. 19 deadline, the firm will not receive a bonus. Unlike the repair efforts on the Santa Monica and Golden State freeways, and also on the eastbound side of the Simi Valley Freeway bridges, the contract for the current project did not include a bonus for completing work early.

But as on the previous reconstruction projects, crews labored 24 hours a day, seven days a week, limited only by noise restrictions on the type of work they could do at night.

Around-the-clock activity helped make up some of the days lost to a late start and the need to develop new construction plans for Bull Creek after flood control officials decided not to allow scaffolding to be based in the channel. The project began late because the previous contractor for the eastbound portion of the freeway had not finished cleaning up in time, Caltrans said.

Because those circumstances were beyond F.C.I.’s control, the company will not be penalized for the delay, officials said.