Route evaluation for hazmat transportation based on total risk - A case of Indian State Highways

Risk-based hazmat transportation route evaluation involves risk calculations taking into consideration the probability of collision related accident occurrence and detailed consequence analysis of various event scenarios. Probabilistic hazmat transportation risk assessment mainly depends on three important factors i.e. accident rate, Average Daily Traffic and population density besides route length which has a definite bearing on it. An effort has been made to estimate the route segment specific (location-specific) accident rate instead of aggregate National or State average values in order to bring specificity into the issue of decision making to avoid routes with higher accident rates. Instead of using default accident rate for different highway types developed with the US data, which are not well-comparable when used in Indian situations; the author used site-specific truck accident data. Subsequently, Loss of Containment (LOC) probabilities and spillage probabilities for different route segments have been computed and compared. Finally, route segment-wise total risk is estimated which is a convenient measure of the average number of persons likely to be exposed from all the possible consequence event scenarios resulting from releases of different hazmats being transported along the studied routes. The present study highlights the route evaluation carried out based on total risk computation, without going through detailed event based consequence analysis on two State Highway routes and one major urban road passing through important industrial corridors of Surat District in western India, to enable routing decisions by local authorities and also for planning emergency mitigation purposes.