It could take up to 40 years for Union Pacific to almost triple the size of its Lathrop intermodal facility that transfers truck trailers to and from railroad cars.

The railroad has hammered out a development agreement with San Joaquin County that establishes timing for previously approved land use and infrastructure improvements. As proposed, the development agreement would be in effect for 25 years with the ability for up to three additional 5-year extensions.

The agreement is before the San Joaquin County Planning Commission when they meet Thursday, June 4, at 6:30 pm. in the auditorium of the San Joaquin County Department of Public Health Services, 1601 E. Hazelton Ave., Stockton.

The decision by UP to expand the Lathrop facility that fronts Roth Road underscores the growing logistically importance South San Joaquin County and Northern Stanislaus County have not only to shipping California agricultural products east but to move goods from local distribution centers to markets in the Bay Area, Sacramento area, and the Fresno-Bakersfield area.

The Lathrop-Tracy-Manteca-Stockton is home to distribution centers such as Amazon, Home Depot, Ford Motor Co., Orchard Supply Hardware, Lineage Refrigeration, Dryers Ice Cream, Safeway, Costco, Best Buy, SSI Industries (SaveMart, Raley’s) and FedEx that is now under construction to name a few.

When the Lathrop  expansion is done, the regional capacity for intermodal movements will soar to 1.3 million units a year between the UP complex and the Santa Fe intermodal facility north off Manteca between Austin Road and Jack Tone Road. That is the equivalent of 3,561 truck movements a day.

The 2001 expansion of the Santa Fe facility increased that railroad’s intermodal capacity in San Joaquin County from 120,000 to 300,000 units annually.

Currently the UP intermodal facility can “lift”  — remove and place truck trailers on specially designed railroad flat cars — on some 270,000 container a year. At build-out that number will reach 730,000 lifts.

The expansion of the UP intermodal facility in Lathrop is expected to double the current workforce of 67 railroad workers to 137. Center Point is developing a 4 million square foot business park tailor made for distribution firms that rely heavily on intermodal transport directly across from the UP facility and within Manteca’s city limits. Center Point’s future tenants are expected to provide 600 permanent jobs.

That, however, is expected to be just the tip of the iceberg. The UP move will increase the demand for truck transportation in the area plus make the immediate community — Manteca and Lathrop particularly — even more attractive to firms that are starting to do more and more cross-country shipping by rail due to the short trip for trips to the intermodal facility.

The average daily truck trips to and from the UP facility would go from 954 today to 2,186 at complete build-out. It would mean the average number of trucks per hour leaving or departing the intermodal facility would go from 39.75 every hour to 91. Weekend traffic is 5 to 10 percent of work day traffic. Monday would be the heaviest day for truck movement at build-out with 2,585 trips compared to 1,056 in early 2011.

UP spokesmen have pointed out that the facility expansion ultimately will reduce truck traffic on major freeways as one freight train moving trailer containers does the work of 280 long-distance trucks

UP now has 67 workers at the intermodal site and ultimately will employ 137.