Abstract
In 1987 and 1988, two important documents were developed concerning the lighting recommendations for vehicular tunnels. These were cie's "guide for the lighting of road tunnels and underpasses" (cie 26/2)(draft), and the ansi/ies "american national standard practice for tunnel lighting" (ansi/ies rp-22). Although these organizations kept a close liaison throughout the preparation of these documents, the photometric values in tunnel threshold zone and the length of supplementary lighting recommended in the documents differ considerably. This paper appears in transportation research record no. 1247, Visibility criteria for signs, signals, and roadway lighting.