Union Pacific Corp., the largest of the two railroad lines moving cargo to and from the ports of Los Angeles and Long Beach, announced Wednesday it will commit more than $1.3 billion to upgrade its 33,000-mile nationwide track system.

Funding will come from Union Pacific’s general operating budget, from where $1.9 billion in capital improvements were allocated in 2004.

The nation’s largest revenue-generating railroad operator also plans to lease 315 locomotives and 4,000 rail cars to handle the rising amount of cargo traffic, especially imports from Asia, under separate capital improvement expenditures.

Union Pacific’s $1.3 billion upgrade project will include the replacement of 1,055 miles of track.

An additional $295 million will be spent to increase capacity in the North Platte, Neb. area, as well as the Sunset Route, on which much of the cargo is moved to and from Southern California ports.

Also, $220 million was allotted for terminals, rail yards and support tracks (for ethanol plants) across the nation.

“The plan is to do as much work as we physically can do,” said Jerry Wilmoth, a spokesman for Union Pacific, who said he did not know how much of the investment is earmarked for projects in the L.A. area.

Tracks from Los Angeles to San Luis Obispo suffered heavy damage during the spate of rain storms that hit the area in January, contributing to the congestion that plagued the region during an otherwise slow traffic period.