The problem seems simple enough: Tractor-trailers account for about 4 percent of the traffic on the Capital Beltway but 16 percent of the accidents.
"People are screaming now, but they'll be screaming even louder once they understand the figures," said Doug Nielson, a spokesman for the American Automobile Association, voicing the complaints of many critics of the trucking industry. "I think our Beltway could rival anyplace in the country in terms of danger."
Yet, as the public outcry has mounted over the recent series of wrecks that have closed parts of the highway around Washington, so, too, has the belief that there is little that can be done in the immediate future to resolve the problem.
If anything, a number of industry and government officials agree, the problem is certain to get worse as traffic on the Beltway increases. Restrictions and regulations being considered would be either unrealistic or ineffective.
And trucks, including the large tandem models now running along the Beltway, have become an essential element in the area's economic life, critics agree.
Compounding that is the sheer volume of traffic on the Beltway, up by 25 percent since 1980. Officials say that the 120,000 vehicles a day that travel the Beltway are pressing the highway beyond its designed capacity.
Sgt. John Bowden of the Virginia State Police notes that the Beltway has become primarily a commuter road, rather than a route for interstate traffic to circumvent the District, as it was originally intended. "The road is saturated," he said. "It is as simple as that."
Arlington County Board member Albert C. Eisenberg, chairman of a regional public safety committee, speaks pessimistically of the problem, noting that the trucks are filled with large quanities of vital but often hazardous materials.
"Urban life requires that you move this stuff around," he said. "Much of it is essential to modern existence. If you don't take it down the interstate, where do you take it?"
The hazards of trucking on the Beltway have come to haunt the daily commuting of thousands in the area:
*On Aug. 12, a tanker truck spilled hazardous chemicals on a section of the Beltway in Fairfax County south of Alexandria, forcing the evacuation of hundreds of homes.
*On Sept. 6, a tanker truck filled with propane leaked on the Beltway in Prince George's County, burning for hours and forcing the evacuation of nearby homes.
*On Sept. 13, a tractor-trailer sideswiped six vehicles on the Beltway in Fairfax County before slamming into a guardrail, killing the driver. Virginia State Police attributed the crash to brake failure.
*On Friday, an empty oil tanker skidded into a retaining wall on the Beltway in Fairfax County. It took nearly two hours for officials to clear the wreckage.
All four accidents temporarily closed portions of the Beltway and led to traffic jams, quickly followed by cries of outrage from local politicians.
Some sections of the Beltway stand out as especially hazardous, Nielson said. About 50 percent more accidents occur on just 25 percent of the Beltway, between Rte. 50 and the Woodrow Wilson Bridge in Prince George's County, than on any other section. Another problem area is on and around the Cabin John Bridge, Nielson said.
The Prince George's section of the Beltway has received especially high use recently because of construction on Rte. 301 in Maryland. And construction on the Cabin John Bridge makes that area accident-prone, Nielson said.
But as unpopular as trucks seem to be, placing limits on their use of the Beltway may be the equivalent of cutting Social Security. Many traffic experts say that the proposals advanced by area politicians to resolve the problem would not necessarily be effective.
And, given the political power of the trucking industry, it is unlikely that drastic limits could be placed on trucks without the industry's acquiesence, officials said. "Without the involvement of the trucking industry, there is no way to make this work," said Fairfax County board Chairman John F. Herrity, a trucking critic.
Confronted by accident trends, the Metropolitan Washington Council of Government's Public Safety Policy Committee drew up a list of resolutions in July to increase safety on the Beltway, including the banning of trucks from the far left lane on most sections of the Beltway, and more resources to inspect trucks carrying hazardous chemicals.
The Fairfax County Board of Supervisors called on COG to endorse strict limits on trucks, and COG agreed to sponsor a conference with the Greater Washington Board of Trade this winter on Beltway safety.
Some politicians, including Herrity, have called for restricting trucks to the right lane and requiring a 40 mph speed limit for trucks.
Since last year, trucks have been prohibited in the far left lane on about half the Beltway.
There are some notable exceptions to the trucking industry's opposition to Beltway restrictions. Arthur E. Morrissette, president of Interstate Van Lines in Springfield, agrees that "banning trucks from the Beltway would be economic folly," but he maintains that restricting trucks to the right lane and imposing a speed limit of 40 mph would reduce accidents and involve only minor delays for trucks.
"If those big behemoths -- and I have over 200 of them -- are going slower, the other traffic is not so intimidated," Morrissette said.
COG's Public Safety Policy Committee will meet again this week, and Eisenberg, the group's chairman, said it is likely that additional proposals for restricting trucks will be discussed. But there are limits to how far restrictions can go.
Even a trucking critic such as Nielson agrees with American Trucking Association official William Johns that restricting trucks to the right lane would probably lead to a steady stream of trucks in that lane, making it difficult for commuters to enter and exit. And, said Johns, studies indicate that expressways are safest when all traffic is moving at the same speed.
Most unrealistic of all are proposals to ban trucks from the Beltway, or to limit their use to certain hours, Johns said. There are no suitable alternative routes, and trucks in general play too great a role in the economic life of the area to ban them, he said.
Even restrictions on trucks carrying hazardous chemicals would lead to an impossible situation, Johns said, because many of the chemicals are everyday substances. "Do you want someone coming to your home at 1 in the morning and saying, 'Okay, I've got your propane'?"
Johns said the trucking industry is eager to find a solution to trucking accidents, but he believes that the answer lies in stiffer roadside truck inspections and more police patrols.
Praising the idea of a COG regional conference to deal with Beltway safety, Herrity said recent accidents underscore the need for construction of an outer beltway to divert truck traffic from Washington.
COG spokeswoman Sherry Conway said that when the Beltway was constructed, it was intended more for use by interstate traffic, not for the volume of local traffic it now carries.
Meanwhile, many sense a whiff of hypocrisy in the recent attention politicians and residents have paid to trucks on the Beltway.
"I'm amused at the recent Fairfax County interest in safety," said Eisenberg. "We've been looking at this issue for over a year."
"You could have a wreck every day and no one would care. It's when it blocks the road, and all of a sudden this is such a big problem," said Sgt. Bowden.
And in the midst of the complaints about trucks, concedes the AAA's Nielson, many people overlook that a large share of the problem rests with irresponsible drivers of automobiles, particularly those who dart in front of trucks.
"A phenomenon has disappeared from roads called courtesy . . . ," he said. "I don't see any way to solve the problem, except for a lot more self-policing from everybody."