The objective of this research was to develop criteria and supporting material (suitable for consideration for MUTCD Sections 2B.04 to 2B.10) for determining appropriate traffic control at an unsignalized intersection. The types of unsignalized traffic control that should be addressed include no-control, yield, two-way stop, and multi-way stop.
In 1983, an ITE Journal article noted that “The Manual on Uniform Traffic Control Devices includes warrants for the use of Yield, Two-way Stop, and Four-way Stop control at intersections. Those existing warrants have undergone little improvement in the past 25 to 50 years to correspond with the advancement in traffic engineering.” (ITE Journal; January 1983; “Guidelines for Use of Sign Control at Intersections to Reduce Energy Consumption”; Upchurch, Jonathan E.) Since then, that MUTCD language has remained largely unchanged. Yet, much has been learned over the decades about the effectiveness of alternative unsignalized intersection control. The relevant chapters in the Highway Capacity Manual (TRB, 2010) have been updated several times and the recently published Highway Safety Manual (AASHTO, 2010) provides techniques to assess the safety of different designs. The current MUTCD criteria largely focus on crash problems, vehicle and pedestrian volumes, and vehicle speed. Many users of the MUTCD have asked for additional guidance for factors such as changes in traffic mix of pedestrians and bicyclists, intersection geometrics, and roadway functional classification.
Task 1. Compile policies and guidelines used by state and local transportation agencies related to unsignalized traffic control decisions and summarize key components. Review the literature on the effectiveness and selection of different types of unsignalized traffic control.
Task 2. Identify intersection and traffic characteristics that may influence the decision on the type of unsignalized traffic control that is appropriate at an intersection. Examples include, but are not limited to, crash history, traffic volumes, functional classification, urban/rural/neighborhood, intersection geometrics, speed characteristics, sight distance, pedestrian and bicyclist use, land use, parking, and bus usage.
Task 3. Critically evaluate the quantitative and qualitative criteria currently included in MUTCD Sections 2B.04 through 2B.10 related to the choice of unsignalized traffic control, including the underlying research and rationale.
Task 4. Submit an interim report summarizing the results of Tasks 1 through 3, identifying MUTCD provisions that deserve further study, and presenting a Task 5 work plan for addressing the critical weaknesses.
Task 5. Carry out the work plan from Task 4, as approved by the panel, to address the critical weaknesses of the current MUTCD as it pertains to unsignalized intersections.
Task 6. Develop potential MUTCD text, tables, and figures. These materials should be clear and directly applicable to the decision on the type of unsignalized traffic control at an intersection. Support statements should be provided to aid in decisionmaking and in explaining the decision to the public.
Task 7. Submit a final report describing the work that was done; presenting the potential MUTCD text, tables, and figures; and documenting the rationale for the proposed MUTCD material.