As you likely know, Metro and Caltrans are working on a project to build a northbound carpool lane on the 405 freeway between the Santa Monica Freeway and the Ventura Freeway. That’s the good news.

The bad news: construction impacts will increase big-time starting Jan. 12, according to the press release from Caltrans and Metro. There will be night-time lane closures on weekdays — some starting after 7 p.m. — and some full freeway closures after midnight. Gulp.

The full release is posted after  the jump. LOS ANGELES – Beginning Tuesday, Jan. 12, 2010 and lasting approximately two months, night-time weekday-only work will begin on the I-405 Sepulveda Pass Widening Project, the carpool lane construction project that will create a 10-mile northbound carpool lane between the Santa Monica (I-10) and the Ventura (US 101) Freeways.

Commuters, residents and businesses in the vicinity should now anticipate upcoming freeway construction impacts and begin planning needed travel alternatives and schedules.

Beginning Jan. 12 for approximately four weeks, contractors are anticipated to work between 7 p.m. to 6 a.m. delineating temporary traffic lanes along the 10-mile Sepulveda Pass freeway segment. The California Department of Transportation (Caltrans) will close all lanes on various segments of the northbound freeway as work schedules require. However, full freeway segment closures will only be between the hours of midnight and 5 a.m.  Dates and locations of these segment closures will be announced before they go into effect and will be posted at metro.net/I-405.

Following lane delineation work, the contractor on Monday, Feb. 15 will begin placing concrete barriers on the 10-mile shoulder of the freeway to isolate the work zone from existing traffic.  Work will take approximately four weeks to complete and will again be conducted between the hours of 7 p.m. and 6 a.m.  During placement of concrete barriers, temporary lane closures will be implemented.  The public should expect ramp closures to start as early as 7 p.m., followed by freeway lane closures at 9 p.m.   All temporary lane and ramp closure information will again be posted in advance at metro.net/I-405.

All construction schedules are subject to change, and based in part on weather conditions.

Although detours and traffic control will be in place, motorists are encouraged to use alternative transportation, such as carpools, vanpools, and public transportation when available to minimize inconvenience during this time.  Motorists can find ridesharing partners on the web at commutesmart.info.  Available public transportation alternatives can be found using Metro’s online trip planner at metro.net.

Motorists requiring roadside assistance in the construction zone should call the Metro Freeway Service Patrol at #399.

The project, a joint effort between Metro and Caltrans, will complete the last remaining carpool lane gap on the I-405, enabling motorists to use carpool lanes in both freeway directions between the San Fernando Valley and Orange County.  The lanes save high-occupancy vehicles one minute per mile during peak commute times.  The project is scheduled for completion in 2013.

For additional project information and ongoing construction updates, visit Metro’s web site at www.metro.net/I-405.