5. PROGRAM EVALUATION (continued)
5.3.3.9 Phoenix – Coral Gables Drive East/West SegmentThe east/west segment of Coral Gables Drive was treated with 3-D and Tyregrip™ materials as well as education and enforcement. Five waves of measurement were made to be sure to encompass the installation of all of the pavement treatments. The 3-D markings were installed between Waves 2 and 3 at the east end of the segment. The Tyregrip™ was installed between Waves 4 and 5 at the west end of the roadway. This section of Coral Gables passes a school and park.
Table 68 and Figure 16 show that overall speed was significantly below baseline by in excess of 2 mph in all post waves. The number of drivers exceeding the limit by 7 mph or more dropped almost threefold from Wave 1 to Wave 5. The increase in the mean speed of speeders in Wave 3 is curious because the proportion of the sample in the lowest category increased and the number and percent of drivers in the highest speed category stayed virtually steady. In any event, the reversal was transitory, and Waves 4 and 5 show markedly lower speeds by speeders. The addition of Tyregrip™ was associated with a significant increase of 0.489 mph in overall speed from the preceding wave but a significant decrease of 0.434 mph in the mean speed of speeders between Waves 4 and 5. The Wave 5 mean speed of 30.006 mph, however, was still well below the baseline speed of 33.683 mph.
Table 68. Phoenix – Coral Gables Drive East/West Segment Speed Results
Wave |
Measure |
|||||||
|---|---|---|---|---|---|---|---|---|
Mean Speed (mph) |
Mean Difference from Wave 1 (mph) |
Mean Above Limit (mph) |
Mean of Speeders (mph) |
N and % At or Under Limit |
N and % < 7 mph Over |
N and % 7+ mph Over |
Total N |
|
1 |
33.683 |
|
5.183 |
8.332 |
9167 |
12840 |
13798 |
35,805 |
2* |
31.509 |
-2.174 (.000) |
3.009 (.000) |
7.416 (.000) |
16166 |
14866 |
9924 |
40,956 |
3** |
31.294 |
-2.389 (.000) |
2.794 (.000) |
9.499 |
21887 |
11800 |
10858 |
44,545 |
4** |
29.517 |
-4.166 (.000) |
1.017 (.000) |
7.048 (.000) |
22806 |
17858 |
9432 |
50,096 |
5*** |
30.006 |
-3.677 |
1.506 (.000) |
6.614 (.000) |
24255 |
17408 |
7201 |
48,864 |
* After the application of education and enforcement |
||||||||
There was clearly no diversion of traffic on this segment of Coral Gables Drive . The vehicle counts for every post wave are well above the count for the baseline. There is no ready explanation for why the traffic volume would have increased to the extent measured. It is possible that the novelty value of the innovative markings actually attracted traffic. Even if this, in fact, occurred, the desired speed reductions were nevertheless achieved.
Figure 16. Speed Classes on Phoenix – Coral Gables East/West Segment
