Comprehensive framework for speed-zone guidelines

Speeding is often considered as one of the major reasons of traffic crashes. As a result, State Departments of Transportations (DOTs) receive requests from communities to decrease speed limits in towns along rural highways. Such requests, coupled with the lack of proper manuals, have forced state DOTs to reduce the speed limits. A proper speed-zone manual is required to establish consistent speed zones across a state. This paper reviewed the literature on speed, crashes, enforcement techniques, and speed-zone manuals. A nationwide survey was conducted to identify various factors affecting the decisions of speed zones establishing. This paper identified best practices based on the literature review and expert opinions, and proposed a comprehensive framework for a speed-zone manual. The Nevada DOT traffic engineers were also interviewed during this research to incorporate their opinions in the framework. The framework provided in this paper has six phases. They are; 1) speed-zone identification; 2) speed-limit determination; 3) transition-zone detailed design; 4) speed-zone approval; 5) speed-limit enforcement; and 6) follow-up study. Relevant studies, and manuals corresponding to each phases were presented in this paper. This framework is useful for NDOT, other state DOTs within the U.S., and transportation agencies worldwide that haven't had speed zone manuals currently to develop a proper speed-zone manual.