In the nation of Partoria, large trucks currently account for 6 percent of miles driven on Partoria' s roads but are involved in 12 percent of all highway fatalities  The very largest trucks-those with three trailers-had less than a third of the accident rate of single-and double-trailer trucks
Clearly, ttherefore, one way for Partoria to reduce highway deaths would be to require shippers to increase their use of triple-trailer trucks
In Partoria, the safety record of the trucking industry as a whole has improved slightly over the past ten years.