Two railroads hope to pry short-haul shippers away from motor carriers with new intermodal offerings.

"If we're going to do more in that market, price discounting alone won't keep customers - competitive door-to-door service will," said John P. Sammon, assistant vice president, intermodal sales and marketing, Consolidated Rail Corp., Philadelphia.With a sluggish economy contributing to trucker ills and a weak transportation policy promising little for crumbling highways, now is the perfect time for railroads to push toward regaining lost traffic, observed Jerry Sheridan, senior assistant vice president, business development and control, Southern Pacific Transportation Co., San Francisco.

Burlington Northern Railroad, Fort Worth, Texas, and Norfolk Southern Corp., Norfolk, Va., agree with that assessment, and the two carriers detailed

plans for boosting their inter-city freight volume at the National Association of Rail Shippers' annual meeting here this week.

As soon as approval is granted by the Federal Railway Administration, BN

plans to use RoadRailers as a feeder service for manufacturers in northern Minnesota, said Robert Ingram, vice president, Burlington Northern Intermodal, Fort Worth.

BN anticipates a daily train consisting of 40 to 50 RoadRailer Mark V units making a round trip between International Falls, Minn., and the carrier's Twin Cities' main line hub, Mr. Ingram said.

Instead of using trailers, BN will deploy BN America containers atop RoadRailer container chassis. BN America is BN's domestic container service.

At BN's Twin Cities hub, the BN America containers will either be transloaded onto tack trains or continue their journey in the RoadRailer mode, he said.

BN also hopes to attract less-than-truckload shippers using two 28-foot ''pup" trailers stacked atop a conventional 48-foot container.

The "pups" will rest on a specially built frame designed jointly by BN and Stoughton Trailers Inc., Stoughton, Mich.

Two of 10 "pup" prototypes were delivered to BN's Chicago hub last week, and the carrier plans test runs between the Windy City and the Twin Cities beginning in late summer or early fall.

Meanwhile, Norfolk Southern Corp.'s Triple Crown Service Inc. subsidiary is testing a 53-foot jumbo trailer and is slated to test run two refrigerated trailers in August.

"We need to focus on door-to-door, not ramp-to-ramp, service," said Peter J. Rickershauser, Triple Crown's vice president, sales and marketing.

Mr. Rickershauser also disclosed that his Fort Wayne, Ind.-based unit is considering extending service into New Jersey; between Detroit and Toronto; between the Twin Cities and Chicago and to the Southwest.

Once its feeder service gets under way, BN will be the only user of RoadRailers, aside from Triple Crown.

Union Pacific Railroad, Omaha, Neb., and CSX Transportation Inc., Jacksonville, Fla., terminated their RoadRailer experiments months ago, selling their units to Triple Crown.

"We have found high-quality line-haul segments that don't have the volume to justify stack trains are ideal for RoadRailer technology," Mr. Ingram said.

BN and Gunderson Inc., Portland, Ore., jointly developed a hitch mechanism 18-months ago, enabling RoadRailers to be attached to BN Intermodal's stack

trains, said Bill Berry, BNI's assistant vice president, domestic containerization.

The actions taken by BN and NS exemplify what railroads must do if they're to going to post market share gains in the 1990s, said William A. Coker Jr., vice president, transportation and traffic, Holly Sugar Corp., Colorado Springs, Colo.

To survive this era of rising shipper demands, intermodal operators must raise their standards to the minimums of premium truck carriers, said Brian H. Bowers, president, Hub City Dallas Terminals Inc., Plano, Texas.

"We can no longer look at rail equipment as potential storage units," Mr. Bowers explained. "Intermodal trailers must be given the same loading and unloading priority given to over-the-road shipments."