Thomas J. Donohue, president of the American Trucking Associations, issued a warning to the railroad industry last summer: "If I find them walking on our lawn all the time, I will turn on the sprinklers."

Now, Donohue has given the spigot a big turn, and the railroads are stomping even harder on his lawn.

The issue: Will Congress raise taxes on big trucks, and, more important, will the lawmakers allow heavier, longer trucks on major highways nationwide? Truck sizes and weights will be dealt with when Congress reauthorizes federal highway legislation next year.

One would expect intense lobbying on such a bread-and-butter issue. But the battle between the ATA and the Association of American Railroads has taken on the hues of a personal feud that is beginning to worry shippers. One shipping group, the National Industrial Transportation League, has made an unsuccessful behind-the-scenes effort to promote a truce.

For months, the railroad association has repeatedly warned that longer, heavier trucks would threaten motorists and tear up highways and threaten the economic well-being of railroads at a time when they are needed to take freight off congested highways. What's more, big trucks now don't pay their fair share of highway taxes, the railroads trumpet at every opportunity.

Donohue apparently had had his fill of the railroad campaign when he issued his sprinkler warning in an interview with the Wall Street Journal in May. Now, it appears, he is following through, and the railroads don't like it a bit.

It seems someone leaked the truckers' game plan to the railroad association. It contains a laundry list of almost every legislative and administrative proposal that would raise railroad costs, slow down trains or increase federal regulation, along with a general timetable for pushing the proposals in Congress and state legislatures.

"It's the legislative equivalent of breaking every window in the building," said one railroad official.

Among other things, the trucking plan would limit each freight train to only one class of hazardous material, eliminating the economies of lengthy trains. It would enforce weight limits for railroad piggyback trailers and containers similar to truck limits. It would require fencing of every mile of the 125,000-plus miles of U.S. railroads. State and local governments could impose noise restrictions on trains and prevent them from operating at certain times of the day.

The ATA also identified $980 million a year in what it considered federal and state rail subsidies, such as Amtrak payments to freight railroads for running their trains, and state rules for tax valuation of rail property. And it called for an "unbiased" study of 19th-century railroad land grants.

One provision would even revive the caboose for hazardous materials trains.

"It's sort of like a rabid dog reaction," said Richard E. Briggs, executive vice president of the railroad association.

Briggs said his group's effort is on a higher plane, as a discussion of major safety and economic issues. He said it is important for the public to know they may face bigger trucks and that they might pay a high economic and environmental price. "You don't see us going around trying to close down truck stops because they're centers for drug-trading," he said.

The trucking industry considers its plan a tit-for-tat defense.

"They want to play that game, I'm going to cost them as much as I can," said Lana Batts, the ATA's senior vice president for government affairs.

Batts said the railroads are having trouble competing with trucks and have turned to scare tactics rather than improve their service and marketing. She said the ATA hasn't even decided whether to propose double- and triple-trailer combinations nationwide; a lot will depend on whether it appears truck taxes will be raised substantially.

Batts said the ATA effort is not in full swing yet, and would be called off if the railroads "call off the dogs" in their anti-truck campaign. Otherwise, she said, "We're just going to have to figure out when and where to strike."

That day may be approaching. Joan Claybrook, a long-time consumer activist who is on the railroads' side in the big-truck fight, said Batts approached her at a meeting Tuesday and said, "You ever do some work on railroad safety issues? I have an agenda."