Citation

Evans L. J. Traffic Med. 1996; 24(1-2): 5-15.

Copyright

(Copyright © 1996, International Association for Accident and Traffic Medicine)

DOI

unavailable

PMID

unavailable

Abstract

Objective: This paper examines how road-user behavior changes in response to changes in traffic system safety thereby generating surprising outcomes from safety interventions. Methods: Studies previously reported in the literature on such interventions as improved vehicle braking and occupant protection devices (safety belts and motorcycle helmets) are reviewed and categorized. Results: In response to changes introduced to increase safety, examples are presented in which the actual outcome was that (1) Safety increased even more than expected, (2) Safety increased as expected (3) Safety increased, but less than expected (4) No observed change in safety (5) The change actually decreased safety (a perverse effect). Correspondingly diverse reactions were found for changes expected to reduce safety, but introduced to achieve other goals. Conclusions: Human behavior feedback, or user response, to changes in safety systems is widespread and can greatly alter outcomes. While difficult to predict, the following pattern appears to apply. If the change is readily apparent to road users (affects vehicle handling, such as improved braking) a user response is likely, whereas if the change affects only injury outcome (occupant protection), no appreciable user responses have been observed.