UC Berkeley SafeTREC and the Center for Pedestrian and Bicyclist Safety (CPBS), a Tier-1 University Transportation Center (UTC) supported by the United States Department of Transportation (USDOT) and led by the University of New Mexico (UNM), has released a Year 1 (2023-2024) research report titled "A context-sensitive roadway classification framework for speed limit setting in the US" authored by UC Berkeley's Julia Griswold, Cheng-Kai Hsu, Melody Tsao and John Bigham; University of Wisconsin-Milwaukee's Robert Schneider; and San Jose State University's assistant professor Marcel Moran. The report proposes a new approach to speed-limit setting that differs from approaches common in the United States.
In the U.S., speed limit setting (SLS) has historically relied on driver-behavior-based approaches, such as using the 85th percentile speed. While these approaches are considered objective and allow for consistent application, they have significant limitations, including drivers’ tendencies to underestimate their speeds, the phenomenon of speed creep, and inadequate consideration of vulnerable road users. These issues may conflict with the Safe System Approach and Vision Zero initiatives endorsed by USDOT. In contrast, context-sensitive approaches, which classify roads based on roadway typologies, have been effectively implemented in countries like New Zealand, Sweden, the Netherlands, and Australia.
Inspired by New Zealand’s One Network Framework, the researchers developed a U.S.-based context-sensitive roadway classification framework that integrates “Place,” which considers surrounding land uses and locational contexts, and “Movement,” which pertains to the road’s transport function.
Using data from the Smart Location Database (SLD) and the Highway Performance Monitoring System (HPMS), the researchers validated their framework through internal reviews and external interviews with state-level practitioners. This process revealed both opportunities and challenges in implementing a context-sensitive SLS approach in the U.S. The findings demonstrate the feasibility of establishing an objective, context-sensitive roadway classification system in the US and provide valuable insights for developing new speed-limit guidance aligned with the Safe System framework.
Read the full publication for more information.
Learn more about UC Berkeley's participation in the Center for Pedestrian and Bicyclist Safety (CPBS).
