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

Table 7

45 MPH model estimation results.

Significant variable	Coefficient estimate	t-statistic	Variable notation
Constant	−1.86	−17.91
Indicator of 11 ft lane width for each direction	−0.06 (0.52)	−0.68 (7.49)
Directional average daily traffic per lane	0.0001	11.73
Segment length	0.65	5.35
Indicator of each direction on 27th st between Old Dairy rd and Kmart Dr	1.58	7.51
Indicator of each direction on Nebraska highway from S 33rd st to S 27th st	0.94	2.71
Dispersion parameter	7.21	2.76
Number of observations	910
Log-likelihood with constant only	−1331.99
Log-likelihood at convergence	−1004.13
McFadden pseudo R-squared	0.25
Chi squared	655.72
Info. criterion: AIC	2.22
Finite sample: AIC	2.22
Info. criterion: BIC	2.27

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