Rails, not roads, urged for cargo. (Up Front).

Thirty fewer commuting hours each year for L.A. drivers by 2020?

That's the promise delivered in a new study that recommends freight now being transported by truck be moved to railroads.

The study singled out L.A. commuters for having wasted 136 hours in congestion during 2000-tops among the cities with populations exceeding 500,000.

"L.A.'s traffic is dreadful and it is getting worse," said Wendell Cox, a principal of St. Louis-based Wendell Cox Consultancy, which conducted the study using data from the Texas Transportation Institute. "Anything we can do in the long run to slow down the growth of truck traffic is going to be very valuable."

Cox, who served on the L.A. County Transportation Commission from 1977 through 1985, was commissioned to conduct the study by the Association of American Railroads.

The study showed that by 2010, a 25 percent shift to cargo trains would save an average of 18 hours in commuting time - and 30 hours by 2020.

That would bode well for commuters who drove an average of 218 hours to and from work in 2000 within the study's target area of L.A. and Orange counties, the western portion of Riverside and San Bernardino counties and the eastern side of Ventura County.

Other than advocating greater use of railroads, the study did not offer solutions for traffic planners.

Local traffic planners said finding cost-efficient means of shifting large amounts cargo from road to rail is easier said than done.

Most rail cargo going through the area is going to or coming from other states, and most of the cargo in trucks is going to the local five-county region. "Trains can't travel door to door," said Luke Cheng, a transportation planning manager for the Metropolitan Transportation Authority. "You cannot build a train depot at every warehouse door and city block."

Along the $2.4 million Alameda Corridor, where cargo is transported from the ports to the rail yards east of downtown, L.A., traffic planners said the number of daily train trips is expected to increase to 100 by 2020, from the 35 to 40 today.

But any relief additional train traffic would bring to the Long Beach (710) and Harbor (110) freeways will be offset by the anticipated doubling within a decade of the $200 billion of cargo that currently flows through both ports, planners said.