Access Design and Management Manual

Transportation Research Record: Journal of the Transportation Research Board, 2008

2006

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 of 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 ¼ mile is sufficient for a range of conditions considering arterial speeds and progression quality; however, more restrictive guidelines of ½ mile should be applied in cases where the anticipated development will reach high levels. In general, the findings are supportive of the guidelines provided in FAC Rule 14-97.

Transportation Research Record, 2007

Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Board's recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs.

2006

This glossary has been prepared to include the terminology of the SIDRA INTERSECTION software. The sources used in preparing this document are the SIDRA INTERSECTION User Guide (2017), the Australian AUSTROADS Glossary, AP-C87-15 (2015) and the US Highway Capacity Manual Edition 6 Glossary (2016). This unique glossary includes many terms that are not included in the Australian AUSTROADS Glossary and the US HCM Glossary. An effort has been made to keep the definitions given in the AUSTROADS and HCM glossaries as much as possible, combine them together, modify as required and incorporate them into the definitions used in the SIDRA INTERSECTION software. The usage in SIDRA INTERSECTION takes precedence where there are discrepancies. Thus, many of the key analysis terms in this glossary have significant differences from those in the AUSTROADS and US HCM glossaries (mostly in the expression but sometimes in the meaning). It is hoped that they represent clearer and more general definitions, for example considering left-hand and right-hand traffic rules and different local traffic engineering practices.

This paper reviews research studies relating traffic operations to access spacing, presents results of specially conducted operations analyses at 22 sites in Connecticut, Illinois, New Jersey, and New York, and sets forth emergent access spacing guidelines. The literature review and operational analyses were performed as part of NCHRP Project 3-52-Impacts of Access Management Techniques. Each site represented an unsignalized driveway for a major traffic generator along a suburban arterial roadway without deceleration lanes. Information was gathered on the number and percentage of through vehicles impacted by right turns. The percentage of through vehicles impacted approximated 0.18 times the rightturn volumes. The impact lengths of through vehicles were determined, and the influence distances were computed. The results were then used to quantify the likely effects of multiple driveways and to establish guidelines for deceleration lanes and access separation distances. Access separation distances for various operating speeds and right-turn volumes were based on the likelihood of minimizing spillback across an upstream driveway over a series of driveways along a 1 ⁄ 4 -mile section of road. For example, to hold the spillback rate to 20% for a 40-mph posted speed, a 285-foot spacing would be needed. When the acceptable spillback rate is reduced to 5%, a 400-foot separation is required.

Curb separates the sidewalk from the roadway. When cars start to invade the pedestrian zone and cross the curb to park on the sidewalk or drive on the sidewalk, it is a sign of poorly regulated traffic. The major problem in urban areas is that the number of cars is increasing rapidly. Too many cars in traffic leads to several problems, for example, air pollution, traffic becomes poorly regulated with more injuries in car traffic accidents (with both pedestrians and drivers being injured), higher costs of health care related to trauma and surgery, devastation of nature. It is very important for the urban areas to legally regulate the number of the cars.

Transportation Research Record, 1999