Truckload carrier Swift Transportation Co. wants to launch a RoadRail route between Portland, Ore., and Los Angeles within 90 days, the company's chief executive said on Tuesday.

Swift, based in Phoenix, Ariz., is the second major truckload company after Schneider National Inc. to make a major commitment to RoadRailer, the bimodal equipment whose trailers have removable rail wheels that allow them to be hauled over tracks or roads.Those plans, and an initial order of several hundred RoadRailer units

from their manufacturer, Wabash National Corp. of Lafayette, Ind., hinge on a contract Swift is now negotiating with Southern Pacific Lines, whose I-5 corridor would handle the rail service component.

''We're getting very close" to finalizing that deal, Jerry Moyes, Swift's chairman and chief executive, said on Tuesday.

Sitting on a panel of truckload chief executives at the Intermodal Association of North America's summer meeting, Mr. Moyes said that RoadRail makes sense only on certain traffic lanes, and therefore will probably never comprise more than a minor portion of Swift's fleet, now at 3,850 tractors and some 5,000 trailers.

Swift has said that it plans two RoadRail trains a week, which may generate some $40 million in revenue.

Mr. Moyes said RoadRail has a promising future on certain high volume lanes, like the I-5 corridor, that can support the 80 to 100 unit trains that Swift hopes to run on that service.

"RoadRail is the direction we want to go in intermodal in the future," said Mr. Moyes, who has been Swift's chief executive since 1984.

He said RoadRail gives the company opportunities it would not otherwise have. It increases capacity on a busy lane without the need to find and hire additional drivers. It also allows the trucker to take advantage of rail without incurring equipment damage that often results from trailers being on- and off-loaded from flatcars. "That is a very big problem," he said.

The largest provider of RoadRailer services is Triple Crown Services Inc., a joint venture of the Norfolk Southern and Conrail. The service has attracted mostly high value cargo, including auto parts.

RoadRailer units are built heavier than standard highway trailers in order to withstand the rigors of rail service, though the heavier tare weight limits the cargo they can carry. Swift, whose revenue was $366 million last year, still has plans to run a RoadRail service on Southern Pacific track between Los Angeles and Chicago. That service would begin after the I-5 route is up and running, said William Riley, Swift's executive vice president and chief

financial officer.

''That would be the second traffic lane. It would be down the line, but how far down I'm not sure," he said.

Mr. Moyes said that with its limited ambitions for RoadRail, Swift will not become a threat to the railroads' domestic double-stack rail service. "We feel we can run a RoadRail program alongside double-stack," he said.

Still, suggesting the railroads are not entirely convinced, the trucking executive said that obtaining the railroad's support for RoadRail has been difficult.

"The railroads have not been totally cooperative on RoadRail. They have been a little resistant to (a mode) that may infringe on the asset base they've built," said Mr. Moyes.

While Swift may have big plans for a North-South service on the West Coast, he said that RoadRail will always be a niche business relative to the company's core regional truckload operation.