Analysis of Injury Severity of Drivers Involved Different Types of Two-Vehicle Crashes Using Random-Parameters Logit Models with Heterogeneity in Means and Variances

Table 4

Marginal effects result of injury severity of drivers involved in different types of vehicle crashes.

Variables	Car-car crashes		Truck-truck crashes		Car-truck crashes
	CD model^a		TD model^a		CD model		TD model
	MI	SI	MI	SI	MI	SI	MI	SI
Random parameters
Age band of car driver (1 if 26–45 years, 0 otherwise)	−0.0146	0.1071
Age band of truck driver (1 if 26–45 years, 0 otherwise)			−0.0311	0.1605			−0.0070	0.0666
Speed limit (1 if 30 mph, 0 otherwise)	0.0232	−0.2318	0.0210	−0.2030	0.0245	−0.1855	0.0121	−0.1832
Fixed parameters
Driver characteristics
Gender of car driver (1 if female, 0 otherwise)	−0.0233	0.1556			−0.0702	0.2695
Gender of truck driver (1 if male, 0 otherwise)			−0.1917	0.7950	−0.0082	0.0318	−0.0254	0.2146
Age band of car driver (1 if 65 years above, 0 otherwise)	−0.0050	0.0276			−0.0326	0.0655
Age band of truck driver (1 if 65 years above, 0 otherwise)			−0.0079	0.0185			−0.0005	0.0034
Vehicle characteristics
Age of car vehicle (1 if 3–10 years, 0 otherwise)					0.0010	−0.0043
Age of truck vehicle (1 if above ten years, 0 otherwise)							−0.0099	0.0566
Car vehicle maneuver (1 if speeding, 0 otherwise)	−0.0017	0.0354			−0.0338	0.1180	−0.0012	0.0060
Truck vehicle maneuver (1 if speeding, 0 otherwise)			−0.0001	0.0002
Car vehicle maneuver (1 if turning, 0 otherwise)	−0.0067	0.0601
Truck vehicle maneuver (1 if changing lane, 0 otherwise)					−0.0208	0.1799	−0.0028	0.0103
First point of impact (1 if front, 0 otherwise)	−0.0056	0.0427			−0.0264	0.0890	−0.0057	0.0980
First point of impact (1 if offside, 0 otherwise)	−0.0717	0.3846	−0.0245	0.3038	−0.0091	0.0946
Roadway characteristics
Road area type (1 if rural, 0 otherwise)			−0.0113	0.0928	0.0184	−0.0929	−0.0014	0.0085
Road area type (1 if urban, 0 otherwise)	0.0149	−0.1433
Road type (1 if dual carriageway, 0 otherwise)	−0.0053	0.0420			−0.0071	0.0381
Road type (1 if roundabout, 0 otherwise)	−0.0014	0.0196
Road type (1 if junctions, 0 otherwise)			−0.0107	0.0752
Environmental characteristics
Light conditions (1 if darkness—no lighting, 0 otherwise)	−0.0004	0.0115	−0.0163	0.0404	−0.0002	0.0007	−0.0239	0.2231
Light conditions (1 if darkness—lights lit, 0 otherwise)	−0.0128	0.0910
Weather conditions (1 if fine, 0 otherwise)	0.0242	−0.1459
Weather conditions (1 if raining, 0 otherwise)			−0.1264	0.4958	−0.0025	0.0280
Season (1 if summer, 0 otherwise)	−0.0101	0.0530
Day of week (1 if weekdays, 0 otherwise)			−0.0107	0.0461			−0.0073	0.0920
Crash time (1 if off-peak time, 0 otherwise)	−0.0180	0.1032			−0.0432	0.1543

^aTD: truck driver, CD: car driver, SI: severe injury, and MI: minor injury.