The main objectives of this study were to develop procedures for estimating the level of service on freeway frontage roads and to determine desirable spacings for ramp junctions. The tasks involved developing (1) procedures for analyzing frontage road weaving sections, (2) recommended spacing requirements for ramp junctions, and (3) a technique to evaluate overall operations on a continuous frontage road section. The two weaving segments analyzed included a one-sided weaving area formed by an exit ramp followed by an entrance ramp and connected by an auxiliary lane and a two-sided weaving area formed by an exit ramp followed by a downstream signalized intersection.
The objective of the research was to develop a procedure for evaluating the operations along one-way and twoway freeway frontage roads. The developed procedure is based on the arterial analysis chapter of the Highway Capacity Manual and includes consideration of the delays that are incurred at ramp junctions. To develop the level-of-service analysis procedure, data were collected at several locations within Texas. Travel time, volume, and access density data were collected at 20 one-way frontage road sites and nine two-way frontage road sites. Delay data were collected at six ramp junctions. The results showed that signalized intersections have the greatest impact on the operations along a frontage road. Access density (i.e., the number of driveways and unsignalized intersections per km) affects the operations along a frontage road segment when greater than 20 acs/km on one-way frontage roads and greater than 16 acs/km on two-way frontage roads. The developed procedure produced reasonable results when compared to the average speed measured at six one-way and six two-way frontage road sites. Predicted results were generally within 3 km/in of measured speeds.
This report is part of a larger study developing a level of service evaluation procedure for freeway frontage roads. The results from this report will aid engineers in evaluating existing and proposed two-sided weaving sections on one-way frontage roads. The procedures developed can be used to estimate the level of service at these types of sections. This, in turn, will aid engineers in prioritizing frontage road improvement projects and/or predicting future operations. Also provided are recommended desirable and minimum exit ramp-to-intersection spacings. The results from this study will be incorporated into the final frontage road analysis package.
"Since the publication of the first edition of the Access Management Manual, the context for transportation planning and roadway design in the United States has been transformed. Transportation agencies and local governments are under growing pressure to integrate land use and transportation policy and achieve a more sustainable, energy-efficient transportation system. This second edition of the manual responds to these developments by addressing access management comprehensively, as a critical part of network and land use planning. The content is interdisciplinary, with guidance pertinent to various levels of government as well as to pedestrians, bicyclists, and motorized vehicles, including trucks and buses, and is strongly grounded in decades of research, engineering science, and professional experience. Greater emphasis is placed on appropriate location of access, and guidance is refined to provide appropriate consideration of context and community issues. Substantial updates aid state and local agencies in managing access to corridor development effectively. Specific guidance on network and circulation planning and modal considerations is included, as well as guidance on effective site access and circulation design. A chapter on corridor management reinforces these concepts with a framework for application of access management in different contexts, along with appropriate strategies for each context. There are also new chapters on network planning, regional access management policies and programs, interchange area access management, auxiliary lane warrants and design, and right-of-way and access control. The manual concludes with an extensive menu of access management techniques and information on their application"--Provided by publisher.
TRB's National Cooperative Highway Research Program (NCHRP) Report 687: Guidelines for Ramp and Interchange Spacing explores guidelines for ramp and interchange spacing based on design, operations, safety, and signing considerations. The report is designed to help aid the decision-making process when an agency is considering new ramps or interchanges on existing facilities, modifying ramps and interchanges of existing facilities, or when planning and designing new highway and interchange facilities. The guidelines also offer standardized definitions measuring ramp and interchange spacing, which have varied in previous design guides. A final report documenting the full research effort related to the development of NCHRP Report 687 was published as NCHRP Web-Only Document 169--
