When you pile a load of sand or gravel or any other "loose load" into an open truck and transport it from one place to another, what happens?

Part of the loads blows off or bounces off, that's what happens. The debris ends up littering the roadway and surrounding terrain.

The percentage of the load that "spills" depends on the height to which it has been piled, the speed of the truck, the number of bumps it its, the force and direction of the wind, and similar factors.

But the principle remains the same. When a loose load is transported without a cover, some of it ends up on the roadway. Things like pebbles and stones lie there until an auto or truck tire passes over them at high speed and flings them back into the vehicles behind them. The damage to windshields alone runs into the millions.

It is idle to argue that insurance companies pay for most of this damage. You and I pay for it in higher premiums.

So this year Del. Charles A. Docter (D-Montgomery) again introduced into the Maryland House of Delegates a bill to require that a cover be placed over loose materials being transported in an open truck Sen. Howard A. Denis (R-Montgomery) introduced a similar bill in the upper house.

The average citizen gives little thought to such legislative proposals. To him, a law requiring covers over loose loads seems about as controversial as a law forbidding a householder to toos his garbage out the window.The assumption is that "of course" the legislature will pass the bill.

It is not a valid assumption. The bill has been defeated before, and it stands a good chance of being quietly scuttled again by the trucking lobby. Albert J. Mascaro, executive vice president of the Maryland Motor Truck Association, is earning his pay, as usual.

When Docter's bill came up in the House Environmental Matters Committee, the Maryland State Police testified in favor of it, as did the American Automobile Association and others. Mascaro was opoposed. He said it would cost $200 per truck to provide canvas covers, a figure others said was too high, and he added that this "would result in higher costs to taxpayers by forcing contractors to make higher bids on public projects." Nobody bothered to point out that the kind of truck usually used for hauling gravel costs about $22,000, so $200 for a canvas cover would therefore be an insignificant item in a contractor's cost of doing business.

After the last witness had been heard, the committee voted 11 to 9 against the Docter proposal. Committee members from the Washington area voted for it, but the trucking lobby flattened them as usual.

I guess that's about all there is to say about the matter - except for noting one interesting "coincidence."

The committee vote was taken on Thursday of last week. On Wednesday, the evening before the vote, Al Mascaro happened to give a friendly little dinner for the committee. About two-thirds of the members accepted his hospitality, and most brought their wives and members of their staffs.

Several who attended were still sighing about the lavish menu when I talked to them over the weekend. One said, "It was the finest array of food and drink I've ever seen - oysters, lobsters, shrimp, a two-inch thick cut of prime rib, the works. I'd hate to think of what the bill came to."

House Majority Leader John S. Arnick (D-Baltimore) is chairman of the Environmental Matters Committee. I asked him whether he saw any impropriety in accepting Mascaro's hospitality and then voting on a bill Mascaro was lobbying against. "None whatever," he said. "The trucking people give a dinner for each committee every year, and the date for this one was scheduled weeks in advance, so it was just a coincidence. I see no impropriety."

So, in the Maryland statehouse, it's business - and pleasure - as usual.That's the way things are done in the Land of Pleasant Living.