Highway Safety Manual (HSM), First Edition

KAI led the publication of the First Edition of the Highway Safety Manual (HSM). The HSM is a user-friendly, applications-oriented document that assists practitioners in integrating safety into their everyday practice. It provides science-based guidance for conducting roadway safety analysis.

The HSM has four parts:

  • Part A – Introduction, Human Factors, and Fundamentals: Establishes a common vernacular and understanding of safety analysis as relates to data quality, crash prediction and understanding the effects of potential solutions.

  • Part B – Roadway Safety Management Process: Presents guidance for conducting network screening, diagnosing crash patterns and trends, selecting countermeasures, assessing economic feasibility of improvements, prioritizing improvements and quantifying the effectiveness of improvements that have been implemented.

  • Part C – Predictive Methods: Contains crash prediction models to enable practitioners to calculate the expected number of crashes on rural two-lane and multilane highways and urban/suburban arterials. The crash prediction models are sensitive to different traffic volume and geometric conditions.

  • Part D – Crash Modification Factors (CMFs): A compilation of higher quality CMFs that represent the relative effectiveness of different geometric elements and operational characteristics implemented and evaluated across a range of previous independent (i.e., not conducted with a direct intent of informing the HSM) research projects and studies.

Relative to the original outline for the HSM, KAI revised the structure of the manual to facilitate its use in-practice; re-wrote and edited draft chapters; created new material to describe the relationship among various parts of the manual; and added text to describe how the manual can be applied to planning, design, operations, and maintenance activities. Ms. Ferguson was a lead researcher responsible for revising previous draft chapters, developing new material and updating example problems to illustrate the methodologies within all parts of the HSM.

With the publication of the HSM, KAI worked with Digiwest to create a software program to automate the crash prediction calculations found within parts C and D of the HSM.