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Table 5 Results of multivariate adaptive regression splines (MARS) analysis for average vehicle speed

From: Effects of weather conditions, light conditions, and road lighting on vehicle speed

Weather and independent variables Coefficients
Any weather
 (Intercept) 71.556593
LightingOrNot −20.053046
h(11 − RoadWidth) 2.743444
h(RoadWidth − 11) 4.305712
h(SpeedLimit − 50) 0.201694
h(SpeedLimit − 60) −1.115876
h(70 − SpeedLimit) −2.200719
h(SpeedLimit − 70) 1.570952
h(SpeedLimit − 90) 0.553183
h(120 − DistanceToIntersection) × LightingOrNot 0.16244
h(DistanceToIntersection − 120) × LightingOrNot 0.085485
h(SpeedLimit − 70) × LightingOrNot 0.414816
h(9.5 − RoadWidth) × h(70 − SpeedLimit) 0.40451
h(RoadWidth − 9.5) × h(70 − SpeedLimit) 0.719237
h(SpeedLimit − 50) × h(Precipitation − 0.42) −0.035494
h(SpeedLimit − 50) × h(0.42 − Precipitation) 0.227114
Clear
(Intercept) 79.981334
LightingOrNot −28.518277
h(11 − RoadWidth) 2.780364
h(RoadWidth − 11) 5.282669
h(SpeedLimit − 50) −0.065991
h(SpeedLimit − 60) −1.136726
h(70 − SpeedLimit) −2.189518
h(SpeedLimit − 70) 1.995838
h(SpeedLimit − 90) 0.573804
h(122 − DistanceToIntersection) × LightingOrNot 0.158861
h(DistanceToIntersection − 122) × LightingOrNot 0.086751
h(SpeedLimit − 50) × LightingOrNot 0.403711
h(9.5 − RoadWidth) × h(70 − SpeedLimit) 0.400246
h(RoadWidth − 9.5) × h(70 − SpeedLimit) 0.700583
h(SpeedLimit − 50) × h(Month − 5) −0.009991
h(SpeedLimit − 50) × h(5 − Month) −0.020567
Rain
(Intercept) 77.395878
LightingOrNot −29.097199
h(11 − RoadWidth) 3.023544
h(RoadWidth − 11) 7.771029
h(SpeedLimit − 50) −0.06837
h(SpeedLimit − 60) −1.05428
h(70 − SpeedLimit) −2.128295
h(SpeedLimit − 70) 1.849517
h(SpeedLimit − 100) 0.840325
h(122 − DistanceToIntersection) × LightingOrNot 0.175531
h(DistanceToIntersection − 122) × LightingOrNot 0.09366
h(SpeedLimit − 50) × LightingOrNot 0.437476
h(9.5 − RoadWidth) × h(70 − SpeedLimit) 0.388002
h(RoadWidth − 9.5) × h(70 − SpeedLimit) 0.688757
h(SpeedLimit − 50) × h(RoadSurfaceTemp − 3.3) 0.00191
h(SpeedLimit − 50) × h(3.3 − RoadSurfaceTemp) −0.022534
Snow
(Intercept) 72.993458
LightingOrNot −23.47263
h(70 − SpeedLimit) 0.620395
h(SpeedLimit − 70) 0.600392
h(−3.16667 − RoadSurfaceTemp) 0.51156
h(RoadSurfaceTemp − −3.16667) 0.258633
h(5 − Month) −1.18959
h(Month − 5) −0.761911
h(50 − SpeedLimit) × LightingOrNot −1.146202
h(SpeedLimit − 50) × LightingOrNot 0.54384
h(5 − DayOrNight) × h(SpeedLimit − 70) −0.009452
h(DayOrNight − 5) × h(SpeedLimit − 70) 0.010379
h(50 − DistanceToIntersection) × h(70 − SpeedLimit) −0.011507
h(DistanceToIntersection − 50) × h(70 − SpeedLimit) −0.001207
h(1590 − DistanceToIntersection) × h(SpeedLimit − 70) −0.000104
h(DistanceToIntersection − 1590) × h(SpeedLimit − 70) 0.000023
h(8 − RoadWidth) × h(70 − SpeedLimit) 0.050211
h(RoadWidth − 8) × h(70 − SpeedLimit) −0.120054
h(SpeedLimit − 70) × h(Precipitation − 1.43333) −0.042663
h(SpeedLimit − 70) × h(1.43333 − Precipitation) 0.175684
  1. DayOrNight light conditions (darkness, twilight, daylight), DistanceToIntersection distance to nearest intersection, RoadWidth road width, SpeedLimit posted speed limit, RoadSurfaceTemp mean value of road temperature per hour, LightingOrNot presence or not of road lighting