AASHTO HSM-1 2014 Supplement

Includes Chapter 18, Chapter 19 and Appendix B to Part C for the Highway Safety Manual, First Edition and 2016 Errata.The Highway Safety Manual Supplement includes two new chapters that help utilize the predictive method to estimate the expected average crash frequency (in total, by crash type, or by crash severity) for both freeways and ramps with known characteristics. The third chapter, Appendix B for Part C, describes two specialized procedures to be used with the predictive method presented in the new Chapters 18 and 19; the first procedure is used to calibrate the predictive models; the second, the Empirical Bayes Method, helps combine observed crash frequencies with the estimates provided by the predictive models.