SOUTHERN CALIFORNIA SPOTLIGHT : San Diego Officials Hope to Restore Historic Rail Line : Commerce: They say reopening the San Diego & Imperial Valley route will help both U.S. and Mexican firms.

Most of the 108-mile San Diego & Imperial Valley Railroad has been closed since 1983, and neglect, violent rainstorms, fires and rockslides have rendered its tunnels and trestles inoperative.

But now an effort is being mounted by San Diego officials--with the support of the Commerce Department--to reopen the line to give San Diego and Tijuana a direct link to the rail grids of the southwestern United States and the interior of Mexico.

The reason is trade. The line, which runs through Godforsaken stretches of mountain and desert east of San Diego and dips for 44 miles into Mexico before joining Southern Pacific’s main line near El Centro, could give U.S. shippers of bulk cargo cheaper, faster access to Asian and Mexican markets.

U.S. owners of maquiladora plants in Tijuana that manufacture bulky furniture and appliances could ship more efficiently to prime markets in the eastern United States.

And by helping increase maritime trade out of San Diego’s underutilized port, the reopened line might give San Diego’s economy--battered by unending defense and aerospace cutbacks--a much-needed lift.

For now, all rail cargo originating in San Diego and destined for America’s heartland or Mexico must travel north to Los Angeles on the Atchison, Topeka & Santa Fe line before turning east. Sending freight over the SD&IV; directly through El Centro would save shippers three days and hundreds of dollars per container or car, according to Fred Byle, the SD&IV;’s assistant general manager.

“With the reopening of the railroad, San Diego would be a highway for goods and not a cul-de-sac, which is what we are right now,” said San Diego City Councilman Juan Vargas, a strong proponent of the railroad, which he calls the “NAFTA Train” because it would exploit the North American Free Trade Agreement.

San Diego is the only major U.S. city served by only one railroad. Tijuana, a growing industrial center and Mexico’s sixth-largest city, has no rail connection at all to the interior of Mexico.

Assistant U.S. Commerce Secretary Charles Meissner, who heads the department’s NAFTA efforts, has voiced support for the railroad. On a recent trip here, he said the SD&IV; could provide a significant economic boost for the region and help NAFTA realize its trade potential.

But skeptics say San Diego will never escape the dominance of Los Angeles and Long Beach, the two transit hubs whose growth made the SD&IV; and San Diego’s port practically superfluous. The same market factors that forced the SD&IV; into disuse will make a reopened rail line a difficult economic proposition, critics say.

Mexico’s peso crisis, beginning with the devaluations in December, has also put a damper on some observers’ enthusiasm. By making U.S. products more expensive for Mexican consumers, the weak peso has reduced the market for exports there.

There is also the matter of financing. According to a new study by the San Diego Assn. of Governments, a regional planning agency, the rehabilitation will cost upward of $75 million, with $40 million coming from government sources. Just which government source will pay and how it will pay has not been worked out.

Not even its strongest proponents say the reopened line will put San Diego in the same league with Long Beach and Los Angeles as a transit hub. But the reopening of the historic railroad, built by sugar magnate John D. Spreckels in 1919, might give the city the basis on which to build a solid niche cargo market, Vargas and others say.

After acquiring the line from Spreckels in 1932, Southern Pacific sold the SD&IV; in 1979 to San Diego’s Metropolitan Transit Development Board so the agency could use the San Diego-San Ysidro segment for its San Diego Trolley. Freight traffic was so sporadic that when two bridges in the desert were destroyed by fire in 1983, the agency never bothered to make full repairs.

The line is now open only between San Diego and the border town of Tecate, Mexico, where its cargo includes barley for the Tecate Brewery.

But the last 10 years have seen solid increases in shipments of autos and bulk cargo in and out of San Diego’s port, making the SD&IV; more feasible.