Synthesis of Safety for Traffic Operations - Transports Canada

Synthesis of Safety for Traffic Operations March 2003
Stop-control
N = exp(-9.34 + 0.60ln ADT main + 0.61ln ADT side + 0.13ND
– 0.0054SKEW) [3.9]
where:
N = annual number of crashes
ADT main = Average daily traffic on the main road
ADT side = Average daily traffic on the minor road
ND = number of driveways on the major road legs within
76 metres of the intersection
SKEW = intersection angle (degrees) expressed as one-half of the
angle to the right minus one-half of the angle to the left
for the angles between the major road leg in the direction
of increasing stations and the right and left legs,
respectively. 2
Signal Control
N = exp(-5.46 + 0.60ln ADT main + 0.20ln ADT side
– 0.40PL – 0.018LT + 0.11V + 0.026T + 0.041ND) [3.10]
where:
N = annual number of crashes
ADT main = Average daily traffic on the main road
ADT side = Average daily traffic on the minor road
PL = 0 if no protected left-turn phasing on major road; 1 otherwise
LT = Proportion of minor road traffic turning left during AM and
PM peak combined (%)
V = grade rate for all vertical curves within 76 metres of the
intersection along the main and minor roads
T = Proportion of trucks entering in the AM and PM peak hours
combined (%)
ND = number of driveways on the major road legs within 76
metres of the intersection
The stop-control SPF was developed using data from 324 intersections in Minnesota,
with five years of crash data. The signal controlled SPF was developed from 18
intersections in California, and 31 in Michigan, each with three years of crash data
available.
2 In most instances SKEW is computed as the absolute value of the angle of intersection minus 90 degrees.
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