AASHTO HSM-1 2014 Supplement, published in 2014, supplements the Highway Safety Manual, First Edition, with additional predictive method chapters. The supplement adds Chapter 18, a predictive method for freeways, and Chapter 19, a predictive method for ramps. These chapters let practitioners estimate expected average crash frequency, in total, by crash type, or by crash severity, for freeways and ramps with known characteristics. A third component, Appendix B to Part C, describes specialized procedures that support the predictive method. The additions extend crash prediction coverage to freeway and ramp facilities not addressed by the predictive methods in the first edition. Highway agency safety analysts applying the predictive method in project development and safety management studies can use the supplement with the base manual.