This report documents the speed reduction impacts of two electronic school zone speed limit signs at United Community Elementary School near Boone, Iowa. The school is situated along US 30, a rural four-lane divided expressway. Due to concerns about high speeds in the area, the Iowa Department of Transportation (Iowa DOT) had replaced the original static school zone speed limit signs, which had flashing beacons during school start and dismissal times, with electronic speed signs that only display the school speed limit of 55 mph during school arrival and dismissal. The Center for Transportation Research and Education at Iowa State University conducted a speed evaluation of the area one week before and one month after the newer signs were installed. Overall, the new sign school zone speed limit signs were more effective in reducing speeds than the original signs. The newer signs were effective for both directions of traffic and for both start and dismissal periods, though results showed that the signs seemed to have a more significant effect on westbound traffic than on eastbound. Although only modest changes in mean and 85th percentile speeds occurred, it should be noted that the number of vehicles exceeding the school speed limit decreased significantly, indicating that the sign had a large impact on high-end speeders. The team will conduct a follow-up study in April 2010 before the local school year ends. (Author/publisher)
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