Wednesday, March 12, 2008

analysis of speed data before and after speed limit change on Cootes Drive

SYNECTICS (October 24, 2004)

“Speed data was collected at two locations: Station 1 (north of the Westaway Road overpass) and Station 2 (immediately north of the study site). Based on a review of the speed data, it was determined that a majority of vehicles at Station 1 are traveling above the posted speed limit (80 km/h). The 85th percentile speeds in the northbound lanes were observed to be higher than speeds in the southbound lanes (100 and 93 km/h compared to 90 and 87 km/h). The relatively high speeds are not surprising, given the roadway environment [emphasis added].

At Station 2, a very high percentage of vehicles were observed traveling above the lower speed limit (60 km/h). Overall, though, speeds are lower than at Station 1. The 85th percentile speeds in the northbound lanes were observed to be slightly higher than speed in the southbound lanes (84 and 76 km/h compared to 75 and 73 km/h).”

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“We have the results back from the 3-day speed/volume studies conducted on Cootes between the IPS and the bridge structure. The studies were conducted November 27, 28 & 29th. The results indicate the 85th %'tile speed heading into Dundas was about 71 km/h and heading into Hamilton, the 85th %'tile speed was 75 km/h. For what it's worth, the 15th %'tile speed was over 50 km/h in both directions.”

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NORTHBOUND (toward Dundas)

Synectics (Stn2) October 2004

City November 2008

84 and 76 (posted 60)

71 (posted 40)

24 and 16km/h diff

31km/h diff

Reduction in speed (84-71=13 km/h)

SOUTHBOUND (toward Hamilton)

Synectics (Stn2) October 2004

City November 2008

75 and 73 (posted 60)

75 (posted 40)

15 and 13km/h diff

35km/h diff

Reduction in speed (75-75=0km/h)

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The initial study (Synectics) recommended the lights with traffic calming.

"To address excessive vehicle speeds on Cootes Drive:

  • Provision of horizontal deflection, in the form of lane narrowing;

  • Provide increased police speed enforcement or use of a speed trailer; and

  • Changing the roadside environment to discourage high vehicle operating speeds."


“Why is the city not doing traffic calming?” Or, put this way: “If cars are speeding, what is the city doing to slow them down?”

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