Table 3

Effect of automated enforcement 1 year after warning period

Hourly vehicle volume*Hourly violation rate*Hourly high speed violation rate*Mean violation speed†Maximum violation speed*Hourly mean speed*
MD (95% CI)MD (95% CI)MD (95% CI)MD (95% CI)MD (95% CI)MD (95% CI)
Fixed
 Time period
WarningRefRefRefRefRefRef
  Citation year 129.0 (−16.6 to 74.7) 3.95 ( 7.60 to 0.30) −0.61 (−1.78 to 0.55) 0.11 (0.023 to 0.20) 1.53 ( 2.24 to 0.82) 1.07 ( 1.62 to 0.52)
  Citation year 211.9 (−0.54 to 24.3) 3.22 ( 4.09 to 2.36) 0.32 ( 0.54 to 0.10) −0.050 (−0.17 to 0.075) 0.95 ( 1.36 to 0.54) −0.072 (−0.46 to 0.31)
 Intercept439 (326 to 551)11.9 (7.36 to 16.44)1.83 (0.44 to 3.21)29.5 (29.1 to 29.9)35.7 (34.4 to 37.0)25.8 (24.7 to 26.9)
Random
 Random parameters
  Citation year 1 (SD)49.6 (26.2 to 93.9)4.7 (2.96 to 7.55)1.42 (0.69 to 2.94)0.70 (0.39 to 1.28)0.64 (0.42 to 0.98)
  Citation year 2 (SD)16.7 (8.6 to 32.3)0.131 (0.059 to 0.29)0.44 (0.24 to 0.81)0.45 (0.25 to 0.82)
  Intercept (SD)146 (101 to 210)5.4 (3.50 to 8.39)1.45 (0.68 to 3.08)0.54 (0.33 to 0.88)1.62 (0.85 to 3.09)1.33 (0.83 to 2.13)
 Correlation
  Year 1 and year 20.080 (−0.50 to 0.61)0.14 (−0.57 to 0.73)−0.31 (−0.75 to 0.33)
  Year 1 and intercept0.33 (−0.085 to 0.65)−0.97 (−0.99 to 0.92)−0.95 (−0.99 to 0.58)−0.15 (−0.62 to 0.40)0.23 (−0.45 to 0.74)
  Year 2 and intercept0.029 (−0.52 to 0.56)−0.72 (−0.97 to 0.38)−0.86 (−0.97 to 0.49)−0.24 (−0.80 to 0.54)
 Residual (SD)143 (102 to 200)12.7 (10.69 to 15.2)7.70 (5.90 to 10.0)1.66 (1.54 to 1.79)3.68 (3.50 to 3.87)4.17 (3.66 to 4.75)
  • Multivariable multilevel mixed linear regression to calculate MD and 95% CI.

  • Bolded results highlight findings whose 95% CI does not cross 0.

  • *Adjusted for day and quarter.

  • †Adjusted for day.

  • ‡Not included in model.

  • MD, mean differences.