The illuminating engineering society (ies) has adopted recommendations for the luminance transition in a tunnel that deviate greatlyfrom the curves proposed by the international commission on illumination (cie) and contained in the din (german standards institute) standard. Ies has based its guidelines neither on practical considerations nor on scientific or experimental foundations. To clarify the discrepancy, the physiological processes of adaptation of the eye during a change in luminance have been modeled, and their impact on therequired luminance in the transition necessary to ensure visibilityhas been derived. Using fry's model for the kinetics of the eye's response and adrian's delta-l model, the course of the luminance transition has been calculated. The results are compared with the ies and cie standards. A comparison of the resulting curve with the curve suggested by cie reveals only small differences. In general, the comparison indicates that the experimentally determined cie curve agrees with results derived from the fundamentals of dark adaptation. Theies suggestion, however, falls short. The eye requires about twice as long to adapt to the luminance transition as the ies proposal allows. This paper appears in transportation research record no. 1327, Visibility, rail-highway grade crossings, and highway improvement evaluation 1991
Samenvatting