The objective of this task was to provide step by step instructions for developing calibration factors for use with the Highway Safety Manual (HSM) safety performance functions. Tasks included the following:Review Part C and Appendix A, Volume 2 of the Highway Safety Manual; Review current literature and state DOT practices on SPF calibration; review the scope of work proposed for the HSM Implementation Pool Fund Study: TPF 5-255 to ensure consistency and avoid information gaps and duplication of efforts; submit a draft outline of the calibration guide for panel review; fully develop draft guidelines that will assist a transportation agency in developing statistically sound calibration factors; submit the draft guidelines to the panel for review, and submit a revised final report that includes the revised guidelines.