Criteria for Justification and Design of Auxiliary Lanes

OBJECTIVES: The objectives of this study are to develop warrants and guidelines for the use and design of right-turn and left-turn auxiliary lanes for both signalized and unsignalized intersections. The availability of such warrants and standards will aide highway design, traffic engineering, and access permitting practices within Kentucky. In addition, the results ofthis study will be integrated into Kentucky's evolving access management program. BACKGROUND: Maximizing the potential capacity of existing roadways is becoming a priority due to growing congestion and limited resources for adding more capacity to the highway system. Including turn lanes in the design of a highway improvement project, or requiring turn lanes to be added as a result of new development, is a complex decision requiring the Cabinet to evaluate the anticipated demands for right or left turns to abutting land development and the anticipated benefits in delay and crash reduction against the cost and other impacts of the installation. The common method of analyzing and designing intersections on the basis of past experience, accident records, complaints from the traveling public, and engineering judgment has led to inconsistencies. Even where technical analysis is attempted, the most commonly used analysis tool (the 1967 Harme1ink Methodology) is of questionable value due to the facts that the underlying assumptions are no longer valid for today's driving conditions and queue storage lengths frequently need to be longer than those indicated by the limits of the Harmelink curves. It is also anticipated that the products of this study will be useful in providing justification for requiring and specifying developer-funded turn lane improvements which may be needed to mitigate the impacts of major traffic generating developments. Better analysis procedures are needed to justify and specify developer-funded turn lane improvements which may be needed to mitigate the impacts of major traffic generating developments in the future. FY 2007 PROPOSED WORK: It is anticipated that the project work and results documentation can be completed within the 2007 fiscal year. PROGRAMMED COST FY 2007: TOTAL ESTIMATED COST: $50,000 $75,000