What is the standard reference for speed percentiles and speed limits?

• A. MUTCD 2B.13
• B. AASHTO 4.2
• C. FMCSA 5.1
• D. ASCE 3.3

Answer: (A)

The Manual on Uniform Traffic Control Devices (MUTCD) is widely recognized as the standard reference for traffic control devices and regulations in the United States. Specifically, Section 2B.13 of the MUTCD addresses the establishment of speed limits, including the consideration of speed percentiles. This section provides guidance on the proper method of setting speed limits to ensure they are reasonable and appropriate for the typical conditions of the roadway, effectively balancing safety and mobility considerations.

In practice, appropriate speed limits are often established based on the85th percentile speed, which is the speed at or below which 85% of the vehicles are traveling. This approach is grounded in empirical research, making the MUTCD a vital resource for traffic engineers when strategizing on speed regulations and ensuring they align with the behavior of road users.

While other references such as AASHTO (American Association of State Highway and Transportation Officials), FMCSA (Federal Motor Carrier Safety Administration), and ASCE (American Society of Civil Engineers) provide valuable information regarding transportation design and vehicle operations, they do not specifically serve as the standard reference for speed percentiles and speed limits like the MUTCD does.