Transportation officials are about to embark on major construction of a $1-billion widening of the 405 Freeway through the Sepulveda Pass, the final leg in their campaign to create continuous carpool lanes between Orange County and the San Fernando Valley.
But they admit that a relatively small percentage of commuters will share in the full benefits of the project.
The extra lane will allow carpoolers and some drivers of hybrid vehicles to traverse the entire 405 -- from the 5 Freeway in Irvine to the 5 Freeway near Sylmar -- using carpool lanes.
Single-occupant vehicles, who make up 85% of current traffic on the 405, are not likely to feel much of a difference in their commutes, particularly during rush hour.
The 405 passes several areas that are key destinations natural for carpooling, including three airports -- John Wayne, Long Beach and LAX -- as well as major universities such as UCLA, Cal State Long Beach, Cal State Northridge and UC Irvine -- and cultural destinations such as the Getty and Skirball centers.
"It serves the airport, it serves the Westside, then UCLA. . . . There's a number of very important venues, and those are the venues that attract people that do carpool," said Doug Failing, executive director of the highway program at the Los Angeles County Metropolitan Transportation Authority.
Failing also said that such a continuous carpool lane could be good for people traveling from Northern California to Southern California or for others who are seeking carpool routes.
More than 300,000 drivers travel on the 405 through the Sepulveda Pass each day, officials said.
The project is scheduled to be completed in 2013. The work will involve lane closures and the closing of entire portions of the northbound freeway at some points.
This is tough news for Westside commuters who have endured other projects on the 405 through West L.A. in recent years.
Officials also say this will probably be the last major widening of the 405 Freeway, because the cost of such projects begins to outweigh the benefits of adding lanes.
That's because the freeway loses some of its capacity as drivers enter the freeway and weave from lane to lane.
"Really, the 405 is approaching the maximum number of lanes that you can do in a continuous segment," Failing said. "There becomes a point of diminishing returns," he said.
Failing said that the next step to reducing congestion should include improving the meters that allow drivers to enter the freeway.
That would mean making the meters smarter to allow more drivers on the freeway when there are upcoming gaps and hold drivers back when lanes are especially crowded.
That same idea can be applied to nearby streets that drivers use to access freeways, Failing said.
He estimated that such a system of smart meters and other similar changes would cost about $25 million to implement on the 405, a small fraction of the cost of adding an extra lane.
A similar project was done on the 210 Freeway, and officials are compiling the data to see how much improvement was made.
Major construction to widen the northbound 405 Freeway and install a 10-mile carpool lane will begin Jan. 12. The MTA and the California Department of Transportation are jointly completing the project.
In addition to the carpool lane, construction authorities will replace the Skirball Center, Sunset Boulevard and Mulholland Drive bridges, widen 13 underpasses and realign 27 on- and off-ramps.