An Analysis of the Effects of Crash Factors and Precrash Actions on Side Impact Crashes at Unsignalized Intersections

Table 5

Random-parameter ordered logit model of injury severity for side impact crashes at four-way intersections.

Y2 = four-way intersection crash injury severity		Model estimates		Marginal effects
Variables and description		β	O	C	B	A	K
Constant		0.042
Precrash actions (base: other behaviors)	Ran stop sign	0.718		−17.00%	4.48%	7.37%	4.73%	0.43%
	Failed to yield at stop sign	0.092		−2.03%	0.67%	0.85%	0.47%	0.04%
	Failed to yield at turn	0.123		−2.77%	0.88%	1.16%	0.66%	0.06%
Urban	Yes	−0.524		12.01%	−3.62%	−5.10%	−3.02%	−0.27%
Crash location (base: other crash locations)	Open country	0.286		−6.45%	2.05%	2.72%	1.56%	0.14%
	Residential area	−0.240		5.25%	−1.78%	−2.17%	−1.20%	−0.10%
	Shopping center	−0.213		4.67%	−1.57%	−1.94%	−1.07%	−0.09%
Roadway geometry (base: curved roadway)	Straight level road	0.143		−3.24%	1.03%	1.36%	0.78%	0.07%
	Straight road with grade	−0.086		1.89%	−0.64%	−0.78%	−0.43%	−0.04%
Turn lane present	Yes	0.103		−2.31%	0.75%	0.97%	0.55%	0.05%
At-fault driver_speeding	Yes	0.775		−18.66%	4.42%	8.18%	5.55%	0.51%
At-fault driver_DUI	Yes	1.048		−25.39%	4.95%	11.21%	8.43%	0.80%
Gender	Male	−0.167		3.71%	−1.23%	−1.55%	−0.86%	−0.07%
Causal driver age	21 years old or younger	−0.263		5.68%	−1.96%	−2.34%	−1.27%	−0.11%
	22∼31 years old	−0.218		4.73%	−1.62%	−1.95%	−1.07%	−0.09%
	32∼41 years old	−0.259		5.56%	−1.93%	−2.29%	−1.23%	−0.11%
	42∼51 years old	−0.242		5.19%	−1.81%	−2.13%	−1.15%	−0.10%
	52∼61 years old	−0.167		3.62%	−1.24%	−1.49%	−0.82%	−0.07%
	62∼71 years old	−0.176		3.82%	−1.31%	−1.58%	−0.86%	−0.07%
Point of impact	Front passenger side	−0.356		7.47%	−2.67%	−3.05%	−1.62%	−0.14%
	Back passenger side	−0.965		17.93%	−7.00%	−7.08%	−3.55%	−0.30%
	Bumper	0.755		−16.76%	5.33%	7.03%	4.04%	0.35%
	Driver door	0.412		−9.57%	2.80%	4.09%	2.46%	0.22%
	Passenger side behind the driver	−0.633		12.64%	−4.72%	−5.08%	−2.63%	−0.22%
Causal vehicle type	Passenger car	−0.138		3.06%	−1.01%	−1.28%	−0.71%	−0.06%
	Pickup	−0.209		4.53%	−1.55%	−1.87%	−1.02%	−0.09%
	SUV	−0.112		2.47%	−0.83%	−1.02%	−0.57%	−0.05%
Noncausal vehicle type	Passenger car	−0.330		7.32%	−2.40%	−3.05%	−1.71%	−0.15%
	Pickup	−0.497		10.40%	−3.71%	−4.24%	−2.26%	−0.19%
	SUV	−0.289	0.819	6.21%	−2.15%	−2.56%	−1.39%	−0.12%
Scale parameters for random parameters	Failed to yield at stop sign	0.523
	Male	0.950
Mu(01)		0.819
Mu(02)		2.003
Mu(03)		4.588
Summary statistics	Number of observations	13,910
	Log likelihood at zero L (0)	−14,882.277
	Log likelihood at convergence L (β)	−14,116.792
	Pseudo-R2	0.051
	Likelihood-ratio test (vs. regular ordered logit)	Prob. = 0.000
	AIC	28,305.6