Publications

Over the years that radioactive material (RAM) transportation risk estimates have been calculated using the RADTRAN code, demand for improved geographic resolution of route characteristics, especially density of population neighboring route segments, has led to code improvements that provide more specific route definition. With the advent of geographic information systems (GISs), the achievable resolution of route characteristics is theoretically very high. The authors have compiled population-density data in 1-kilometer increments for routes extending over hundreds of kilometers without impractical expenditures of time. Achievable resolution of analysis is limited, however, by the resolution of available data. U.S. Census data typically have 1-km or better resolution within densely-populated portions of metropolitan areas but census blocks are much larger in rural areas. Geographic resolution of accident-rate data, especially for heavy/combination trucks, are typically tabulated on a statewide basis. These practical realities cause one to ask what level(s) of resolution may be necessary for meaningful risk analysis of transportation actions on a state or interstate scale.

Estimation of the potential radiological risks associated with highway transport of radioactive materials (RAM) requires input data describing population densities adjacent to all portions of the route to be traveled. Previously, aggregated risks for entire multi-state routes were adequately estimated from population data with low geographic resolution. Current demands for geographically-specific risk estimates require similar increases in resolution of population density adjacent to route segments. With the advent of commercial geographic information systems (GISs) and databases describing highways, U.S. Census Blocks, and other information that is geographically distributed, it became feasible to determine and tabulate population characteristics along transportation routes with 1-kilometer resolution. This report describes an automated method of collecting population data adjacent to route segments (for calculation of incident-free doses) based on a commercial GIS. It also describes a statistical method of resolving remaining resolution issues, and an adaptation of the automation method to collection of data on population under a hypothetical plume of contamination resulting from a potential transportation accident.