Overview
Before ESL After ESL Difference
Average % average over SL 85th SL Average % average over SL %ile speed % drivers over SL 85th SL Average 85th
I-635, Dallas County, Belt Line 68.9 6.1% 74 65 66.8 11.3% 5.5% 94.5% 72 60 -2.2 -2.0
US 75, Collin County, FM 543 69.0 -1.4% 74 70 66.6 2.5% 38.2% 61.8% 71 65 -2.4 -3.0
US 380, Collin County, Collins 67.5 -3.6% 72 70 63.9 -1.7% 64.5% 35.5% 67 65 -3.6 -5.0
US 380, Denton County, US 377 64.6 70 70 65 (incomplete data available)
I-635, Dallas County, Scyene 69.1 6.3% 75 65 65.9 9.8% 12.1% 87.9% 71 60 -3.2 -4.0
I-30, Rockwall County, FM 551 68.3 -2.5% 73 70 67.1 3.3% 31.7% 68.3% 71 65 -1.1 -2.0
I-20, Dallas Cty, St. Augustine 72.6 75+ 70 65.6 69 65 (removed because value highly irregular)
I-35, Dallas County, Keaton Rd. 68.4 -2.2% 72 70 68.5 5.4% 23.1% 76.9% 73 65 0.1 1.0
I-35, Denton County, FM 407 70.4 0.6% 74 70 68.5 5.4% 27.2% 72.8% 73 65 -1.9 -1.0
US 67, Ellis County, N. of 287 66.7 -4.6% 71 70 64.9 -0.1% 55.5% 44.5% 70 65 -1.8 -1.0
US 287, Ellis County, FM 664 67.9 -3.0% 72 70 66.0 1.6% 45.3% 54.7% 70 65 -1.9 -2.0
I-45, Ellis County, US 287 bus. 70.6 0.9% 75+ 70 70.0 7.6% 17.2% 82.8% 75 65 -0.6 0.0
US 80, Kaufman County, Spur 557 69.6 -0.5% 74 70 69.7 7.3% 14.9% 85.1% 74 65 0.1 0.0
US 175, Kaufman County, FM 148 69.0 -1.4% 74 70 68.3 5.1% 21.9% 78.1% 73 65 -0.7 -1.0
I-20, Kaufman County, FM 740 70.0 0.0% 75+ 70 68.7 5.7% 28.1% 71.9% 75 65 -1.2 0.0
Averages 68.8 -0.4% 67.2 4.9% 29.6% 70.4% -1.6 -1.5
Explanation: Average: average speed
% average over SL: % average speed is higher than speed limit
% drivers over SL: % of drivers exceeding the speed limit
%ile speed: percentile speed that speed limit represents
85th: 85th percentile speed, a key figure for determining the appropriate speed limit.
SL: posted speed limit
Difference: difference of indicated figure before and after ESLs
Notes:
1. The 85th percentile speeds for I-45, Ellis County, US 287 bus. and I-20, Kaufman County, FM 740 are actually "75+". The radar tally sheets had one checkbox for any speeds 75 or higher. The 75+ notation was converted to 75 to enable rudimentary mathematical modeling.
2. The posted limit is on average 8 MPH below the 85th percentile speed limit, resulting in, on average, 30th percentile speed limits (criminalizing 70% of all drivers).