Crash Frequency Minimization with Severity Mitigation in Road Geometric Design Using Chance Constraint Programming Optimization

Table 5

35NCBD model estimation results.

Significant variable	Coefficient estimate	t-statistic	Variable notation
Constant	−1.25	−15.35
Indicator of 9 ft lane width for each direction	−0.36	−4.05
Indicator of 10 ft lane width for each direction	−0.28 (0.52)	−4.17 (14.26)
Indicator of 11 ft lane width for each direction	−0.30	−4.18
Indicator of 1 lane for each direction	−0.62	−11.94
Indicator of one way road	0.39	3.37
Indicator of each direction on 27th st between Nebraska highway and Cornhusker highway	0.93	15.26
Indicator of each direction on 40th st between Van Dorn st and Pioneers Blvd	1.6	10.61
Directional average daily traffic per lane	0.0003 (0.89D-04)	23.635 (26.518)
Dispersion parameter	7.14	6.70
Number of observations	2290
Log-likelihood with constant only	−5544.58
Log-likelihood at convergence	−3001.87
McFadden pseudo R-squared	0.46
Chi squared	5085.41
Info. criterion: AIC	2.63
Finite sample: AIC	2.63
Info. criterion: BIC	2.66

Random parameter, the standard deviation of parameter distribution is shown in parentheses.