The Effects of Traffic Composition on Freeway Crash Frequency by Injury Severity: A Bayesian Multivariate Spatial Modeling Approach

Table 2

Descriptive statistics of variables in the model.

Variables	Description	Mean	SD	Min.	Max.
Response variables
No-injury	No-injury crash count per segment in 2014	3.60	2.98	0	20
Injury	Injury crash count per segment in 2014	0.86	1.03	0	5
Crash exposure variable
DVKT	Daily vehicle kilometers traveled (10^3 km⋅pcu)	44.3	16.9	9.98	129
Risk factors
	The percentages of vehicles of Category 1	38.3	0.70	37.6	40.3
	The percentages of vehicles of Category 2	2.59	0.23	2.24	3.05
	The percentages of vehicles of Category 3	21.8	0.31	21.0	22.4
	The percentages of vehicles of Category 4	6.58	0.27	6.18	7.06
	The percentages of vehicles of Category 5	30.7	0.87	28.9	31.6
Curvature	Segment horizontal curvature (0.1 k)	1.77	1.27	0	4.35
Gradient	Segment vertical gradient (%)	0.741	0.568	0	2.91
Bridge	A part of a bridge: Yes = 1, No = 0	0.500	0.502	0	1
Ramp	Presence of ramps Yes = 1, No = 0	0.210	0.407	0	1

: passenger car units