Virginia's three major railroads yesterday won a key vote in their effort to rid their tracks of the lowly caboose, a cherished perk of train workers that the rail giants say costs them millions of dollars a year.

Represented by several of Richmond's best known lobbyists and armed with an eight-minute video portraying the caboose as a useless relic, the industry persuaded a subcommittee of the House of Delegates to vote to repeal Virginia's 78-year-old law requiring rail companies to attach cabooses to their trains.

The panel's 4-to-2 vote set the stage for the full committee to approve the repeal when it meets again on Thursday. Ten of the legislators listed as cosponsors of repeal measure are on the 20-member House roads committee.

Meanwhile, some Northern Virginia lawmakers said they want to exchange their support for the no-caboose bill for an industry commitment to obtain long-awaited liability insurance to open a commuter rail line linking Fredericksburg and Manassas to Washington.

"There are bills in the General Assembly that are needed by the railroads, and there has to be a little quid pro quo," Del. David G. Brickley (D-Prince William) said Monday night at a meeting of the Northern Virginia delegation.

The problem of obtaining adequate liability insurance has been a key stumbling block holding up the commuter rail project.

Yesterday's debate on the no-caboose bill pitted lobbyists for the CSX Corp. and Norfolk Southern, two of the nation's largest rail concerns, and the Richmond, Fredericksburg & Potomac Railroad against two representatives for the United Transportation Union, which represents conductors, brakemen and other rail workers.

Union lobbyist H.W. Kitts defended the Virginia caboose statute, one of only two such state laws in the country, as a safety regulation that has gained importance as trains have gotten bigger and faster and carry more hazardous materials.

Kitts said the industry is trying to "dupe" the General Assembly with assurances that cabooses are irrelevant to safety concerns. "We cannot be charged with the responsibility of negotiating public safety" away, Kitts told the lawmakers.

The railroad lobbyists, including William G. Thomas of Alexandria and former state officials Junie L. Bradshaw and Charles J. Davis III, countered by ridiculing the caboose law -- and cabooses in general -- as expensive nuisances, costing the industry $6 million a year in switching and maintenance costs.

"Let's do away with the affection for the little railway caboose," Bradshaw said.