Spatial Influence Analysis of Traffic Safety in Diverging Areas between Freeway Segments and Off Ramps

Table 2

Nominal variables description for diverging area analysis.

Variables	Descriptions	Values and meanings	Frequency
			0	1
Ramp.Lanes	Number of lanes of a ramp	0, 1; 0 denotes 1 lane; 1 denotes 2 lanes	57	15
Up_Interstate.Lanes	Number of lanes of up interstate	0, 1; 0 denotes 1 and 2 lanes; 1 denotes 3 and 4 lanes	40	32
Down_Interstate.Lanes	Number of lanes of down interstate	0, 1; 0 denotes 1 and 2 lanes; 1 denotes 3 and 4 lanes	45	27
Median_Type	Median type (1 to 4 scale): 1 = curbed; 2 = positive barrier; 3 = unprotected; and 4 = none	0, 1; 0 refers to scale 1, scale 2, and scale 3; 1 refers to scale 4	43	29
PSR	Present serviceability rating (0 to 5 scale): 0 = extremely deteriorated pavement; 5 = pavement in excellent condition	0, 1; 0 denotes rating 3.5; 1 denotes rating 2.5, rating 3, rating 3.9, and rating 4.1	60	12
Truck_Percent	Percent truck related	0, 1; 0 denotes 4, 6, 7, and 9 percent; 1 denotes 11 percent	27	45