Potential MUTCD Criteria for Selecting the Type of Control for Unsignalized Intersections (2015)

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4 CHAPTER 1: INTRODUCTION RESEARCH PROBLEM STATEMENT The 2009 Manual on Uniform Traffic Control Devices (MUTCD) (1) 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. The values for volumes and crashes contained within Sections 2B.04, 2B.06, 2B.07, and 2B.09 of the 2009 edition of the MUTCD have not been evaluated based on research since that time. Research was desired to examine the warrants (criteria) in Part 2B for determining whether an intersection should have no control, yield control, or stop control. This National Cooperative Highway Research Program (NCHRP) project was tasked with developing criteria and supporting material for determining appropriate traffic control at unsignalized intersections. The types of unsignalized traffic control to be addressed included no control, yield control, two-way stop control, and all-way stop control. The material produced was to be suitable for integration into an update to the 2009 MUTCD Sections 2B.04 through 2B.09. RESEARCH OBJECTIVES The objective of this NCHRP project was to develop criteria and supporting material for determining appropriate traffic control at unsignalized intersections. RESEARCH APPROACH The research was conducted within seven tasks. Each task listed is followed by the objectives of that task:  Task 1. Compile Policies and Guidelines, and Conduct Literature Review. The objective of this task was to compile policies and guidelines used by state and local transportation agencies related to unsignalized traffic control. In addition, the research team reviewed literature on the effectiveness and selection of different types of unsignalized traffic control.  Task 2. Identify Intersection and Traffic Characteristics. The objective of this task was to identify intersection and traffic characteristics that may influence the selection of an appropriate type of unsignalized traffic control for an intersection.  Task 3. Critically Evaluate MUTCD Sections 2B.04 through 2B.09. The objective of Task 3 was to evaluate quantitative and qualitative criteria currently included in MUTCD Section 2B.04 through 2B.09, along with the findings from Task 1 and Task 2 related to the choice of unsignalized traffic control, including the underlying research and rationale.  Task 4. Develop Task 5 Work Plan and Submit Interim Report. The objective of this task was to develop and submit the interim report summarizing the results of Tasks 1 through 3, identifying provisions that deserve further study, and presenting a Task 5 work plan for addressing critical weaknesses.  Task 5. Conduct Work Plan. The objective of this task was to conduct the approved work plan from Task 4.

5  Task 6. Develop Potential MUTCD Materials. The objective of this task was to develop materials for the MUTCD that would be ready for consideration by the National Committee on Uniform Traffic Control Devices (NCUTCD) and recommended to the Federal Highway Administration (FHWA).  Task 7. Prepare Final Report. The objective of this task was to prepare this final report. The final report describes the work done; presents the potential MUTCD text, tables, and figures; and documents the rationale for the proposed MUTCD material. REPORT STRUCTURE This final report summarizes the results of the various project tasks, documenting the research team’s activities, methodology, and findings. This report has seven chapters and one appendix:  Chapter 1: Introduction describes the problem statement, objective of the project, research approach, and report structure.  Chapter 2: Review of Policies and Guidelines includes a summary of guidelines in the 2009 MUTCD and policies listed in various state and local manuals. It also includes a summary of findings from outreach to traffic engineering practitioners.  Chapter 3: Literature Review includes a summary of key reference documents along with previous research on selecting traffic control devices for unsignalized intersections and pedestrian traffic control device treatments at unsignalized intersections.  Chapter 4: Intersection and Traffic Characteristics identifies the intersection, traffic, and safety characteristics that affect decisions made regarding traffic control at an unsignalized intersection.  Chapter 5: Critical Review includes a summary of the research team’s observations and review of the numeric and general criteria in the 2009 MUTCD. It also summarizes the key considerations for the Phase II work plan.  Chapter 6: Economic Analysis documents the steps taken by the research team to conduct the economic analysis used as a basis for recommending guidance on appropriate traffic control.  Chapter 7: Overview, Conclusions, and Recommendations summarizes the research team’s efforts in conducting the research and describes researchers’ recommendations for revised traffic control at unsignalized intersections based on the findings and conclusions from the research.  Appendix provides the research team’s recommended text of proposed changes to the 2009 MUTCD developed at the conclusion of the project.