TRACTOR/TRAILER ACCIDENT STATISTICS

This paper describes the analysis that was performed to construct (1) a new truck accident event tree, including branch point probabilities and the fractional occurrences of route wayside surfaces, (2) new truck accident speed distributions and (3) new estimates of truck accident fire probabilities. The branch point fractions needed to construct the new event tree were calculated using truck accident data for the years 1996 through 2000 and vehicle mileage data for the years 1997 and 2000. Truck accident data were also used to estimate the fraction of bridge accidents that result in the truck falling off of the bridge. A count of bridges on Interstate 95 yielded a conservative estimate of the number of truck accidents that might lead to collisions with very large bridge columns. The occurrence frequencies of route wayside surfaces and surfaces under bridges were developed using Geographic Information System databases and methods of analysis.