Influence of Multiple Freeway Design Features on Freight Traffic Safety

Table 1

Descriptive statistics.

Variable	Mean	S.D.	Min.	Max.
Total crashes	5.153	7.472	0	49
Truck-involved crashes	1.765	3.550	0	16
Natural logarithm of AADT (veh/day)	11.066	0.666	9.250	12.453
Section length (mile)	0.731	0.931	0.101	6.972
Number of lanes	2.683	0.795	2	5
Maximum speed limit (mph)	64.981	5.843	50	70
Horizontal curve (1 = yes, 0 = no)	1 = 739 sites, 0 = 1402 sites
Inside shoulder rumble strips (1 = yes, 0 = no)	1 = 1494 sites, 0 = 647 sites
Outside shoulder rumble strips (1 = yes, 0 = no)	1 = 1534 sites, 0 = 607 sites
Lane width (ft)	12.034	0.199	11	15
Inside shoulder width (ft)	7.718	3.611	2	17
Outside shoulder width (ft)	9.922	1.741	2	17