Safety Impacts of Push-Button and Countdown Timer on Nonmotorized Traffic at Intersections

Table 2

Model estimation results for random parameters negative binomial model of pedestrians’ crash frequency at intersections (all random parameters are normally distributed).

Variable	Parameter coefficient estimate	-stat (90% CI)	Average marginal effect
Constant	1.33	16.28
Push-button (1 if intersection has push-button; 0 otherwise) (standard deviation of parameter distribution)	−0.81 (−0.34)	−10.03 (−3.69)	−4.03
Countdown timer (1 if intersection has countdown timer; 0 otherwise) (standard deviation of parameter distribution)	−0.25 (−0.87)	−4.09 (−12.82)	−1.24
Average annual daily left turn traffic (vehicle per day)	0.06	1.71	0.30
Ratio of major direction AADT to minor direction AADT	0.09	2.69	0.45
Number of through traffic lanes	0.07	2.45	0.35
Number of left turn traffic lanes (standard deviation of parameter distribution)	0.18 (1.49)	4.29 (27.64)	0.90
Dispersion parameter, α	0.32	13.45
Number of observations	1001
Log-likelihood with constant only,	−2850.78
Log-likelihood at convergence,	−2538.02
	0.35