NORTHEAST -- Mechanics Valley Road is a wicked creature.
Its cracked, undulating pavement resembles an alligator's back. The rutted spine curves down toward U.S. 40, where gaping potholes await unwary drivers.
Cecilia Farrow knows what created this brute outside her home: the ceaseless pounding of big dump trucks loaded with sand and gravel from a nearby quarry.
Mrs. Farrow, 72, who drives to work at a convenience store, says the creature jars her nerves and jolts her car's suspension.
"I realize the road's bad, but I'll forget sometimes and take it too fast and 'uh-oh,' I'll bottom out," says Mrs. Farrow, accompanied by the basso rumble of passing trucks. "I think it's very dangerous."
State officials point to Mechanics Valley Road in Cecil County as a prime example of the damaging effects of heavyweight dump trucks. Maryland is the only state with no limit on how much weight the rear axles of a dump truck may carry.
A recent study by the State Highway Administration found that the cost of this liberal policy has been high.
Each year, dump service vehicles -- a category that includes dump trucks, cement mixers and refuse trucks -- cause an estimated $26 million of damage to state roads and bridges.
"We're the most lenient state in the country, and as a result, we've got the most damage to our roads from dump trucks," says Hal Kassoff, the agency's administrator. "They are the most damaging vehicles on the roadway."
Maryland law limits the overall weight of loaded dump trucks to 65,000 pounds -- 70,000 in the western counties of Allegany and Garrett.
That is considerably less than the maximum 80,000-pound weight permitted for a five-axle tractor-trailer.
But weight distribution is the key factor, civil engineers say. It's the difference between standing on thin ice and lying across it to rescue someone from drowning.
Since dump trucks have shorter frames and generally fewer axles than other heavy trucks, their weight is concentrated.
The SHA study found, for example, that a fully loaded dump truck is more than three times more damaging to roads than a comparable tractor-trailer and 10,000 times more destructive than an automobile.
Moreover, dump trucks hasten the deterioration of bridges so much that 249 state- and county-owned spans have special weight restrictions for these vehicles.
"The only thing the pavement understands is the axle load," says Earle S. Freedman, SHA deputy chief engineer for bridge development.
"The total load doesn't mean anything. You can go out to any quarry and see the difference in the roads."
Clearly, Mechanics Valley Road is an extreme case. But engineers insist that pavement damage caused by dump trucks is widespread, though usually less obvious than near a quarry.
For example, heavily laden garbage trucks can be more destructive to a city street than all the neighborhood cars and delivery trucks put together.
In Maryland, most dump trucks are tandem axle, meaning that they have two axles in the rear. New Jersey, Virginia and West Virginia restrict such trucks to 34,000 pounds total on the rear axles. It is the limit recommended by the federal government and enforced in a majority of states.
Because Maryland has no such restriction, tandem axle trucks often carry as much as 54,000 pounds on their rear wheels and are two to three times more destructive than their counterparts in other states, the SHA study estimates.
On Mechanics Valley Road, the cracks and rutting are obvious in the southbound lane, where loaded quarry trucks must brake for traffic light. But the damage seems much less in the northbound lane, which serves returning, empty dump trucks.
"It's hard to explain to the public why we have to repair one road every five years when the road outside their home has not been touched in 20 years," says Brian N. Bolender, Cecil County's acting roads supervisor.
"We resurfaced Mechanics Valley Road just three years ago. It's probably one of our worst roads in the county."
Legislation proposed last week by the state Department of Transportation would restrict single-axle trucks to 20,000 pounds and tandem-axles to 36,000 pounds, as measured by weight over their rear axles.
In addition, trucks with three rear axles would be restricted t46,000 pounds, measured on the rear axle, and all overweight trucks would face larger fines.
The new regulations would take effect in 1999.
Trucking industry leaders say they will fight the legislation. They dispute the SHA findings on pavement wear, which were based on mathematical computations, and they fear that any new load restrictions will further burden truckers already reeling from the effects of an economic recession.
"This isn't a bunch of facts. This is a bunch of allegations," said Gene Higgins, president of the Maryland Motor Truck Association.
"We're opposed to this under any conditions. We don't think the data's there to support the contention."