5. PROGRAM EVALUATION (continued)

5.3.3 Speed Results

The large samples of speed data indicated a consistent pattern of reductions in all neighborhoods and on all test segments except 85 th Lane in Peoria . The general pattern of results is a decrease in mean speed accompanied by a moderate to large reduction of drivers exceeding the speed limit by 7 mph or more and a concomitant increase in drivers proceeding at the speed limit or less. The mean speed above the speed limit and the mean speed of speeders also decline significantly at all sites except 85 th Lane in Peoria where the mean speed above the limit declines significantly from Wave 1 to Wave 2 but then returns to baseline in the subsequent measurement waves.

Traffic volumes varied across the various study measurements without a consistent pattern. At six of the study segments (85 th Lane, 91 st Avenue, Clarendon, Moon Valley East/West and North/South and Coral Gables North/South), the volume was essentially equal between the baseline and the last applicable measure. There was a meaningful decrease in traffic volume at two segments (84 th Avenue and Sweetwater) and a notable increase in traffic at two others ( 95 th Avenue and Coral Gables East/West). The decrease in volume on 84 th Avenue after the installation of speed humps is not surprising and has been previously noted when these vertical treatments were installed. The other decrease and the two increases cannot be readily explained but are likely just normal variability.

Importantly, there is nothing in the traffic volume results that suggests that the observed speed reduction effects were the result of diverting higher speed drivers to other, non-studied streets where they would continue to be a hazard. On 84 th Avenue , volume dropped 29.7 percent from the first (baseline) wave to the last measurement. Over the same time period, the number of vehicles traveling 7+ mph over the speed limit decreased by 80.3 percent . On Sweetwater, the number of vehicles counted declined by 4,862 from the baseline to the last measurement while the number of vehicles measured at 7+ mph over the limit dropped by 8,606.