The focus of this paper is on improving the highway transportation system for older drivers through the maintenance of adequate sign legibility and conspicuity. A need for standards is suggested by reports of increasing costs arising from tort liability cases. The discussion covers driver requirements (i.e., demand for conspicuity and legibility) and how they are affected by driver age, supply of conspicuity and legibility under current design practice, and alternative methods of implementing conspicuity and legibility requirements. There appears to be a consensus in the literature that sign-related problems of older drivers require the highway community to do more than erect bigger and brighter signs. Improvements in sign management, multiple signing, placement, and other new approaches are critical. Signs should be installed with sufficient size to require no more than 40 ft/in. of legibility. Signs should be inspected to ensure that the physical condition of the sign and the mounting is maintained and that required contrast is retained. Sheeting of higher reflectivity should be used to achieve adequate conspicuity for critical purposes and where sign placement reduces luminance because of high observation and entrance angles. The effects of age on information-processing time and short-term memory suggest that an effort be made to reduce the Minimum Required Visibility Distance (MRVD) and specifically the perception-reaction time (PRT) required for certain signing situations. This can be done through the use of symbols, color and shape codes, multiple signing, and placement. Standards and specifications should be reviewed to eliminate unjustifiable restrictions that may interfere with valid performance improvements. Leadership is needed to ensure that the needed research is conducted, and the procurement process should be evaluated. Changes should be made that would favor research plans including adequate testing of the effects on older drivers of any signing or other highway improvement.

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  • Accession Number: 00489618
  • Record Type: Publication
  • ISBN: 0-309-04664-5
  • Files: TRIS, TRB, ATRI
  • Created Date: Nov 30 1989 12:00AM