Access connections and signalized intersections in the vicinity of an interchange can greatly affect the operations of the arterial and the freeway mainline.Previous studies on this topic have been focused on operations (e.g. arterial delays) and policy issues (e.g., right-of-way acquisition). The focus on this study was primarily on operations issues, but the intent was to take a more comprehensive approach, simultaneously considering several factors that influence arterial operations near an interchange. The main objective was to develop some quantitative tools and guidance for the location of signalized intersections in the vicinity of interchanges. The main sections of this report include the following: a literature review that provides a summary of technical studies, state practices, and national guidelines for access management; a discussion of diamond interchange design issues and their relationship to arterial operations; an overview of available simulation and analytical methods for the analysis of arterial operations in interchange areas; an overview of the relationship between signal spacing and other related factors on progression quality; and the development of tools for the assessment of arterial operations in the vicinity of interchanges. The recommendations for minimum signal spacing near interchanges derive firstly, from the consideration of progression quality at the arterial and secondly, from the estimation of the operating speed and the desired level of service. A software tool was developed that can be used by analysts to assess, at the planning level, the effect of several roadway, traffic, and control variables on arterial operations. The tool has two main features: 1. it will provide an assessment of the adequacy of a given signal spacing with respect to progression quality, and 2. it will provide an estimate of the average travel speed between the interchange off-ramp and fist downstream signal, as a function of arterial and driveway operational characteristics and signal distance. The research findings indicate that a minimum signal distance of 1/4 mile is sufficient for a range of conditions considering arterial speeds and progression quality; howver, more restrictive guidelines of 1/2 mile should be applied in cases where the anticipated development wil reach high levels. In general, the findings are supportive of the guidelines provided in FAC Rule 14-97. (Author/publisher)
Samenvatting