In which manual can the safety performance functions be found?

• A. Roadside Design Guide
• B. AASHTO Safety Manual
• C. Highway Capacity Manual
• D. Manual on Uniform Traffic Control Devices

Answer: (B)

The AASHTO Safety Manual is the correct reference for finding safety performance functions. This manual was specifically developed to provide guidance on safety analysis and the implementation of countermeasures to improve roadway safety. Safety performance functions are statistical relationships that estimate the number of crashes that may occur under specific road conditions, allowing engineers and planners to evaluate and compare safety across different roadway designs and interventions.

In contrast, the other manuals serve different purposes. The Roadside Design Guide focuses on roadside safety and design principles to reduce the severity of crashes involving roadside objects. The Highway Capacity Manual provides methodologies for evaluating the capacity and level of service of various transportation facilities, but it does not specifically address safety performance functions. The Manual on Uniform Traffic Control Devices primarily establishes standards for traffic control devices, such as signs and signals, rather than detailed safety performance metrics. Each of these other documents contributes important information to the field of transportation, but the AASHTO Safety Manual is uniquely dedicated to safety performance analysis.