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

Table 4

Random-parameter multinomial logit model of precrash actions for side impact crashes at four-way intersections.

Y1 = precrash action (base: other behaviors)		Ran stop sign			Failed to yield at stop sign			Failed to yield at turn
Variables and description		β	ME	β	ME	β	ME
Constant		−1.648			−0.134			−4.028
Urban	Yes				0.067		−2.06%
Crash location	Open country	0.013		0.03%				0.096		−0.07%
	Residential area	0.734		2.61				−0.523		0.19%
	Shopping center	−0.217		−0.47				0.145		−0.15%
Roadway condition	Dry							1.860		−3.54%
	Wet							1.874		−0.53%
Lighting condition	Daylight	−0.096		−0.61%	0.423		4.89%	−0.039		0.07%
	Dark without lighting	0.598		0.37%	0.175		0.16%	0.743		−0.12%
	Dark with lighting	−0.178		−0.15%	0.037		0.05%	−0.129		0.03%
Roadway geometry	Straight level road	1.141		12.26%	1.472		17.96%
	Straight road with grade	1.345		1.65%	1.172		2.28%
Turn lane present	Yes	−1.495		−1.38%	−1.199		−3.54%
No functioning traffic control	Yes	−1.559		−1.89%	−2.258		−6.66%	1.085		−1.08%
At-fault driver_speeding	Yes				−4.024		−0.37%	−4.219		0.00%
At-fault driver_DUI	Yes	−1.899		−0.23%	−3.734		−0.46%	−2.793		0.01%
Gender	Male				−0.230		−1.64%
Causal driver age	21 years old or younger	0.197		0.37%	0.029		0.09%
	22∼31 years old	0.269		0.53%	−0.234		−0.72%
	32∼41 years old	0.161		0.19%	−0.127		−0.25%
	42∼51 years old	−0.209		−0.17%	−0.393		−0.63%
	52∼61 years old	−0.105		−0.09%	−0.080		−0.13%
	62∼71 years old	−0.051		−0.04%	0.052		0.08%
Point of impact	Front passenger side	0.601		0.55%	0.266		0.33%	−0.724		0.04%
	Back passenger side	0.362		0.27%	0.095		0.11%	−0.444		0.03%
	Bumper	0.160		0.51%	0.708		4.57%	1.003		−1.46%
	Driver door	0.275		0.25%	0.209		0.31%	0.435		−0.09%
	Passenger side behind the driver	0.095		0.07%	0.116		0.15%	0.117		−0.02%
Causal vehicle type	Passenger car				0.372		2.81%	0.342		−0.42%
	Pickup				0.314		0.85%	0.124		−0.05%
	SUV				0.489		1.26%	0.291		−0.14%
Noncausal vehicle type	Passenger car							−0.089		0.10%
	Pickup							−0.138		0.06%
	SUV							−0.296		0.12%
Scale parameters for random parameters in precrash actions	Straight level road	1.137
	Urban				1.793
	Causal vehicle: SUV				0.721
Summary statistics	Number of observations	13,910
	Log likelihood at zero L (0)	−19,283.355
	Log likelihood at convergence L (β)	−12,703.043
	Pseudo-R2	0.341
	Likelihood-ratio test (vs. regular multinomial logit)	Prob. = 0.000
	AIC	25,556.1

Significance at 1%; 5%; 10% levels.