Consistent, reliable estimates of release accident rates are essential when using risk assessment to compare the safety of rail and truck for a given shipment of hazardous materials. The estimates that appear in the literature have shortcomings or inconsistencies that make it difficult, if not impossible, to perform such a comparison.Yet claims are made that one transport mode is safer than the other, and risk assessors are using estimated accident rates that are out of date or inaccurate. This paper derives benchmark estimates of release accident rates for the two modes using department of transportation (dot) incident reports to count the number of release accidents in 1982, and official statistics of the Interstate Commerce Commission (ICC) and the Census Bureau to evaluate the level of exposure to release accidents in that year. In addition to providing useful reference data for future risk assessments, the results show that there can be no general answer to the question of which mode is safer, since it depends on the release accident rate (which varies with release severity, carrier type, vehicle type, and track or road type) and such other factors as the size and design of the containers used.
Samenvatting