Part A describes the purpose, scope, and intended audience of the HSM. The HSM exists to provide analytical tools, techniques, and processes for quantifying the potential effects that decisions made in planning, design, operations, and maintenance have on overall crashes. The information in the HSM intends to help agencies integrate safety into their decision-making processes. When used properly, the HSM can be integrated into all facets of the project development process. It also provides a brief introduction into the core elements of human factors that affect the interaction between drivers and the roadway. Although there is no specific design guidance provided in the HSM related to human factors, the information related to human factors is intended to support the information provided in Parts B, C, and D. A more detailed discussion on human factors is available in the NCHRP

Report 600: Human Factors Guidelines for Road Systems. The last chapter in Part A introduces the fundamental concepts needed to understand the roadway safety management techniques and crash estimating methods presented in the subsequent parts of the HSM. This chapter includes an overview of the following fundamental concepts:

For greater understanding of Part A, please refer to the HSM.