The objective of this research was to develop design guidance for channelized right-turn lanes, based on balancing the needs of passenger cars, trucks, buses, pedestrians (including pedestrians with disabilities), and bicycles.
The revised final report has been published as NCHRP Web Only Document 208.
Many transportation agencies use channelized right-turn lanes to improve operations at intersections, although their impact on safety for motorists, pedestrians, and bicyclists is not clear. The Americans with Disabilities Act (ADA) requires that all pedestrian facilities, including sidewalks and crosswalks, be accessible to pedestrians with disabilities. The U.S. Access Board has published draft rights-of-way guidelines requiring pedestrian signals at channelized turn lanes. Research in NCHRP Project 3-78A, “Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities,” is addressing this issue. Regardless of the outcome of that research, some agencies may remove existing channelized right-turn lanes and avoid constructing new ones. Guidance is needed to help make these decisions based on reliable data on their safety impacts.
For the purposes of this project, a channelized right-turn lane is characterized by separation from the through and left-turn lanes on the approach by an island and separate traffic control from the primary intersection. The channelized right-turn lane may or may not have a deceleration lane entering it and it may have a merge or an auxiliary lane at the exiting end.
Task 1. Prepare a report summarizing existing practice and research related to the design and safety of channelized right-turn lanes. The report should include and build on information contained in the final report for NCHRP Project 3-72, “Lane Widths, Channelized Right Turns, and Right-Turn Deceleration Lanes in Urban and Suburban Areas.” The report should be submitted to the NCHRP, revised based on panel comments, and resubmitted in a format suitable for posting on the NCHRP website.
Task 2. Develop a data collection and analysis plan to determine the safety and operational impacts associated with different types of channelized right-turn lanes. This plan will support the development work that will be carried out in Tasks 5 and 6. Data collection sites should be geographically diverse and include significant nonmotorized use. At least one site should be near a school or another destination that children walk to.
Task 3. Submit an interim report, within 4 months, to document Tasks 1 and 2 for review by the NCHRP.
Task 4. Carry out the Task 2 data collection and analysis plan as approved by the project panel.
Task 5. Develop a process for determining whether a channelized right-turn lane should be installed at an intersection. Factors that may influence the decision on installing a channelized right-turn lane include passenger car, large vehicle, pedestrian, and bicycle volumes; safety history; gap availability on the receiving road; weaving and queues due to a downstream intersection; roadway classification; and the presence of a sidewalk. To the extent practical, these factors should be handled quantitatively although it is expected that several will need to be addressed in a more qualitative manner. A warrant is not anticipated.
Task 6. Develop a reasonable number of typical design diagrams for situations where channelized right-turn lanes are desirable. Diagrams should be included for merging and auxiliary lane designs. These typical design diagrams should address the needs of all of the roadway users (e.g., passenger cars, pedestrians, bicycles, pedestrians with disabilities, and large vehicles). The diagrams should include details such as the island dimensions, roadway radii, stopping and intersection sight distances, design speed, and crosswalk location.
Task 7. Develop a user’s guide for applying the results of Tasks 5 and 6. The user’s guide should include a sufficient amount of supporting material to give the designer confidence in the process and typical design diagrams.
Task 8. Develop recommended text for the AASHTO Policy on Geometric Design of Highways and Streets incorporating the results of Tasks 5 and 6. Develop text for other affected AASHTO documents (e.g., Guide for the Planning, Design, and Operation of Pedestrian Facilities; Guide for the Development of Bicycle Facilities).
Task 9. Submit a final report that documents the entire research effort. The Task 7 user’s guide and Task 8 text should be included as stand-alone appendices.