Evaluation of Two Convex Mirror Systems by Government Drivers

A nationwide field study of two types of convex mirror systems was made by the National Highway Traffic Safety Administration (NHTSA) with the cooperation of the General Services Administration (GSA) for a 10-month period starting in January 1974. One convex mirror system, called the Type I system, consisted of a non-adjustable convex mirror on the right fender, the original outside mirror on the driver's door, and a larger inside mirror. The Type II mirror system consisted of an adjustable convex mirror mounted on each fender and the original inside rearview mirror.

A total of 515 Federal employees evaluated these two convex mirror systems at six major test locations to provide 627 questionnaires. An analysis of the questionnaires shows that drivers preferred the Type II convex mirror system over the Type I. From comments received, it seems that the drivers objected mostly to the non-adjustable feature and restricted field of view of the Type I system rather than to the fact that it was only a one-convex mirror system as compared to a two-convex mirror system. However, neither convex mirror system was rated as highly as the periscope system was evaluated in a previous field test of 50 periscope equipped GSA automobiles (1)*. This suggests that drivers would prefer unit magnification mirror systems with larger rearward fields of view over convex mirror systems with roughly the same view; nevertheless, drivers also prefer the convex mirror systems tested over conventional mirror systems because the convex mirrors provide greater rearward visibility.