Innovative Operational Safety Improvements At Unsignalized Intersections

Two forms of automated motor-vehicle speed control, speed display boards and photo-radar, are compared. The study was conducted on three comparable streets in Riverside, California, over a 4-week period.

Although both devices produced substantial speed reductions while in operation, only display boards demonstrated carryover effects. The enforced display board produced a substantial short-term (but not longer-term) carryover effect; the unenforced display board demonstrated a longer-term (but not short-term) carryover effect, but only at the alongside location, 1 week after its removal. The three cost-effectiveness estimates generated showed that the unenforced speed display board was the most cost-effective; the enforced display board came in second; and the photo-radar placed third.

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