Regional and short-line railroads have a future, providing they get a little help from their friends, executives said.

To start with, short lines would welcome a hand from their big brothers, said Orville Harrold, president of the Providence and Worcester Railroad."We should be working partners, not competitors," he said at the annual spring meeting of the New England Rail Shippers Association held here this week.

Although most trunk lines realize the importance of having viable short- line connections, some still believe all shipments should originate or terminate on trunk line carriers, Mr. Harrold said.

He called for an end to this thinking and asked major rail carriers to market their short-line connections with the same zeal Class 1 roads tout their own services. But more crucial to the survival of short lines is diversification, said Robert Grossman, chairman and chief executive officer of the St. Lawrence and Atlantic Railroad.

"If you want to be in the railroad business, you can no longer have a narrow scope," he told attendees.

That's why the SL&A's parent, Emons Holding Co. of York, Pa., will open a 15,000-square-foot distribution center in its headquarter town later this month. The facility will be the transfer site for fresh produce and canned goods hauled from the West Coast by the Union Pacific Railroad and Consolidated Rail Corp., he said. After the rail haul, goods will trucked to their destination in Norfolk, Va.

The York warehouse represents the first distribution foray for Emons' fledgling logistics division, Mr. Grossman disclosed.

He added that Emons, realizing where the future lies, is converting a 44,000-square-foot shop it used to build railcars into a transloading center for steel and other heavy bulk materials.

Emons plans additional facilities for its other two rail subsidiaries, York Rail and the Maryland & Pennsylvania Railroad, Mr. Grossman said. "We hope to work with other operators as well as construct our own facilities."

Taking similar chances is what kept the Vermont Railway afloat, recalled John Pennington, president of the 160-mile short line operating in the Green Mountain State.

In 1975, that VR experimented with a "Tank Train," which consisted of interconnected 26,000-gallon tank cars. The large-capacity cars were chosen to prevent overloading when being filled with No. 1 or No. 2 fuel oil. The train could be loaded or unloaded from one car, he said.

The experiment proved a success and the VR now moves some 70 million gallons of petroleum products a year from Albany, N.Y., to Burlington, Vt., Mr. Pennington revealed. That's more than all other rail carriers combined, he said.

The executive also demonstrated how short lines should move quickly to protect themselves when their operations are threatened.

In 1983, when the Delaware and Hudson Railway decided to jettison its Whitehall, N.Y., to Rutland, Vt., segment, the VR raced to buy the line over which its Tank Train operates.

Not only must short lines endeavor to find new customers, it must keep current ones happy, said Maggie Silver, president of Pinsly Railroads, which operates short lines in Massachusetts and Florida.

However, any plans devised by short lines will be for naught if motor carriers succeed in legalizing heavier and longer equipment, the executives warned.

At present, truckers are limited to 80,000 pounds gross weight on highways, a standard that includes the weight of a 15,000-pound tractor.

Truckers want the limit to be raised to 117,000 pounds, Mr. Harrold said. Motor carriers also want the right to operate 48-foot trailers in tandem, (they now can run 28-foot pups), he said.