The highway and railroad operating environments for hazardous shipments in the U.S.-safer in the '90s?

This paper seeks to illuminate the status of transportation safety and risk for large-quantity shipments of spent commercial reactor fuel and mixed and hazardous wastes by examining road and rail accident and vehicular travel data from the mid-1990s. Of special interest are the effect of speed limit changes on controlled-access expressways (chiefly the Interstate Highway System) and the possible effect of season-to-season climatic variation on road transport. We found that improvements in railroad technology and infrastructure have created a safer overall operating environment for railroad freight shipments. We also found recent evidence of an increase in accident rates of heavy combination trucks in states that have raised highway speed limits. Finally, cold weather increases road transport risk, while conditions associated with higher ambient temperatures do not. This last finding is in contrast to rail transport, for which the literature associates both hot and cold temperature extremes with higher accident rates.