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AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under National Cooperative Highway Research Program Project 3-109 by the Texas A&M Transportation Institute (TTI), Texas A&M University, Jim Pline, and Peter Koonce. Kay Fitzpatrick, TTI senior research engineer, was the principal investigator. The other authors of this report are Marcus Brewer (TTI associate research engineer), Gene Hawkins (associate professor at Texas A&M University), Jim Pline (consultant), Peter Koonce (consultant), Paul Carlson (TTI research engineer), and Vichika Iragavarapu (TTI assistant research engineer). The work was performed under the general supervision of Dr. Fitzpatrick. The authors wish to acknowledge the many individuals who contributed to this research by participating in discussions regarding this research, including the panel and members of the National Committee on Uniform Traffic Control Devices. The authors would also like to acknowledge the TTI staff members who conducted some of the literature reviews and made several of the VISSIM runs, including James Robertson, Perla Torres, and Alex Valdez. viii
ABSTRACT The 2009 Manual on Uniform Traffic Control Devices (MUTCD) includes guidance for the use of various types of traffic control at unsignalized intersections. Despite changes and advances in traffic engineering in recent decades, the MUTCD content related to selection of traffic control in Part 2B has seen only minor changes since 1971. In an effort to update the MUTCD, this research addressed the following types of unsignalized traffic control: no control, yield control, two-way stop control, and all-way stop control. The research team developed recommendations using information available from reviews of existing literature, policies, guidelines, and findings from an economic analysis, along with the engineering judgment of the research team and panel. The language proposed for the next edition of the MUTCD for unsignalized intersections developed at the conclusion of this research is provided in the appendix. It includes consideration of high-speed (rural) and low-speed (urban) conditions along with the number of legs at the intersection. Because the number of expected crashes at an intersection is a function of the number of legs, the decision on appropriate traffic control should also be sensitive to the number of legs present. The proposed language includes introductory general considerations, discusses alternatives to changing right-of-way control, and steps through the various forms of unsignalized control from least restrictive to most restrictive, beginning with no control and concluding with all-way stop control. Supplemental notes are provided to suggested additions to the current text, which show the reader the source(s) of the material and/or the research teamâs reasoning for proposing the text. ix
