Risk assessment for national transportation of selected hazardous materials

A quantitative risk assessment was conducted to estimate the national risk from transporting (a) six toxic-by-inhalation (TIH) chemicals that account for more than 90 percent of total TIH transportation-related risk, (b) liquefied petroleum gas, (c) gasoline, and (d) explosives. For TIH materials, highway and rail transportation and two classes of incidents are examined. those occurring (a) during a traffic accident or train derailment and (b) en route from origin to destination but not during an accident or derailment. For the other toxic materials, only accident-related incidents in highway transportation are considered, because these materials are dominated by highway incidents. An overview is provided of the hazardous materials and their consequences, the risk assessment method, the databases used to determine hazardous materials commodity flow and incident rate. and study results. To illustrate the method used, the risk assessment for ammonia is discussed. Risk distributions and quantitative risk measures for additional materials as calculated in the study are also presented, and conclusions drawn from these results are discussed. This study has demonstrated the capability to evaluate the national risk of transporting certain hazardous materials. The risk distributions provide valuable information on the probability of certain effects in a given time period, whereas risk measures provide a convenient way to compare relative risk for different commodities, transportation modes, and incident types.