The model for analyzing and selecting routes is being developed by the Railroad Research Foundation, an affiliate of the American Association of Railroads. The regulations say the study must take into consideration 27 factors, including the length of the trip in distance and time; the type and maintenance level of the track; its grade and curves; and the "availability of practicable alternatives."
It will be up to the railroads to decide how much weight to give to each factor, which concerns some experts.
"Spreading the effort across so many factors is likely to prolong and weaken the analysis unnecessarily," said Theodore S. Glickman, a professor of decision sciences at George Washington University in a written response to the rules, calling the effort "unworkable and unlikely to result in adequate protection of target cities."
Railroads "are limited in their choices" of how they can transport cargo, notes Mark D. Abkowitz, a Vanderbilt University engineering professor and author of a recent book on responding to major accidents and incidents.
There are far fewer options than for trucks, which can readily avoid bridges, tunnels and city centers, he said.
"I don't think that the railroad industry ... is looking to sweep this under the rug," Abkowitz said, saying that industry officials "are going through a genuine effort to try to come up to a reasonable way of reconciling this question."