405 North Opens Early from Montana Ave. On

All lanes of the northbound San Diego (405) Freeway reopened at midnight after planned improvements were completed 29 hours earlier than scheduled, a Metro spokesman said Sunday.

This means a third round of closures scheduled for midnight to 5 a.m. Monday will not be necessary, according to spokesman Dave Sotero. Motorists will be spared another round of traffic delays and detours along a 2.4-mile stretch between Montana Avenue and Getty Center.

Clear skies and quick work by crews with contractor Kiewit Infrastructures West are credited with making it unnecessary to close the freeway overnight, and close three of its five lanes on today.   

Earlier 405 closures between 1 a.m. and 5 a.m. Saturday resulted in slowed traffic and backups that also jammed Westside surface streets with drivers attempting to avoid the 405 gridlock.

Starting at 6 a.m. and lasting until about 8 p.m. Saturday, five lanes of traffic were funneled down to two on the northbound freeway next to the Getty Center, causing a passel of fender-benders along the way that further complicated matters.

The 405 north was crawling at 10 miles an hour as far back as Venice Boulevard, and there was also stopped traffic on ramps to the 405 from the Santa Monica (10) Freeway.

Caltrans guardrail repair work on the parallel Topanga Canyon Boulevard created a two-mile backup on that twisting canyon alternative.

"It's a safety issue and we need to repair that guardrail in that canyon," Caltrans spokeswoman Lauren Wonder told City News Service.

The freeway snarl was brought about by a project to shift lanes in the area to the west.

Workers moved the center median and repaved and re stripped the freeway.

Metro officials, who are handling the $1 billion-plus reconstruction process, warned for weeks that 55 hours of full and partial closures of the northbound freeway in the Sepulveda Pass would negatively affect traffic.     

But quick work overnight, including improvements to the carpool lane, also known as the high occupancy vehicle lane, means the crucial connection from West L.A. to the San Fernando Valley is now open, Sotero told CNS.

"The HOV lane now under construction will ultimately extend 10 miles between the I-10 and U.S. 101 and complete the last remaining gap in the I-405 HOV lane network," Sotero said.

The project included realigning and rebuilding dozens of on- and off-ramps, installing the northbound carpool lane, and widening and repairing the 50-plus-year-old freeway.

Most of the 10 miles of widened freeway will be open to traffic by mid- summer, but the final segment won't be open until mid-2014, Metro officials said last month.

Problems removing hillsides and the discovery of hidden utility lines and runoff pipes have caused delays on improvements near Sunset Boulevard, officials said.