Citation

Byun J, McShane WR, Cantilli EJ. Transp. Res. Rec. 1979; 709: 6-10.

Copyright

(Copyright © 1979, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Transportation accident experience depends on many factors, some very subtle. Although many countermeasures are introduced to enhance safety, it is also true that the accident experience can vary systematically over time even if no countermeasures are introduced. This variation in the baseline is investigated in this paper. How can the average condition vary if no new changes are introduced? Simply put, there are variations built into the total system--operators, roadway, and vehicles. Four major forces are considered in this paper: the changing age distribution of the automobile-driving population; the changing urban-rural balance; changes in modal trip lengths or vehicle types; and modal shifts induced by transportation system management actions. Each of these is found to have a significant effect (5-10 percent on the baseline), and other such forces can also exist. Clearly, it is not valid to explicity or implicitly assume that the baseline does not change.