A New GNB Model of Crash Frequency for Freeway Sharp Horizontal Curve Based on Interactive Influence of Explanatory Variables

Table 5

Estimated and statistics parameters.

Estimated parameter	Model 1	Model 2			Model 3	Model 4			Model 5	Model 6
		2.1	2.2	2.3		4.1	4.2	4.3
α0	1.93	1.37	0.56	1.59	2.96	1.58	0.48	1.42	5.00	3.81
α1	0.29	0.17	0.30	1.00	0.31	0.15	0.33	1.00	0.78	0.60
α2	-0.77	-1.10	1.00	-0.23	-1.60	-1.33	1.00	-0.72	-14.05	-11.70
α3	-0.001	1.00	-0.76	-1.41	-0.001	1.00	-0.65	-0.73	6.62	7.85
α4	—	—	—	—	—	—	—	—	0.003	0.015
α5	—	—	—	—	—	—	—	—	9.29	8.49
	—	—	—	—	—	—	—	—	-2.79	-2.41
	—	—	—	—	—	—	—	—	0.38	0.64
	—	—	—	—	—	—	—	—	-0.001	-1.09
	—	—	—	—	—	—	—	—	-0.004	-5.80
λ0	—	—	—	—	2.06	-0.63	-0.93	-0.82	—	1.17
λ1	—	—	—	—	-8.22	-0.18	0.12	-0.15	—	-6.35
β	0.36	0.46	0.45	0.811	—	—	—	—	0.23	—
AIC	401.13	407.63	406.32	431.79	398.47	409.22	408.12	431.79	400.71	393.99
BIC	413.51	417.54	416.23	441.70	413.33	421.61	420.50	441.70	427.96	423.72
Pseudo R2	0.03	0.02	0.02	0.01	0.04	0.016	0.023	0.039	0.059	0.080
LR chi2	11.13	6.12	9.38	4.57	15.76	6.52	9.41	15.96	23.54	32.24