Development of Left-turn Lane Warrants for Unsignalized Intersections
Author | : |
Publisher | : |
Total Pages | : |
Release | : 2010 |
ISBN-10 | : OCLC:844362162 |
ISBN-13 | : |
Rating | : 4/5 (62 Downloads) |
Download or read book Development of Left-turn Lane Warrants for Unsignalized Intersections written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Left-turn movements at intersections, including driveways - especially movements that are made from lanes that are shared with through traffic - cause delays and adversely impact safety. Although left-turn warrants have been updated, many agencies still use research performed by M. Harmelink from the mid-1960s. While most states use procedures that are based on Harmelink, a number of limitations of Harmelink's procedure have been identified. Economic analysis can provide a useful method for combining traffic operations and safety benefits of left-turn lanes to identify situations in which left-turn lanes are and are not justified economically. This project used a benefit-cost approach to determine when a left-turn lane would be justified. The steps included simulation to determine delay savings from installing a left-turn lane, crash costs and crash reduction savings determined from safety performance functions and accident modification factors available in the "Highway Safety Manual," and construction costs. Left-turn lane warrants were developed for rural two-lane highways, rural four-lane highways, and urban and suburban roadways. In addition, warrants for bypass lanes were developed for rural two-lane highways. A "Design Guide on Left-Turn Accommodations at Unsignalized Intersections" was developed that discusses left-turn lane designs, traffic control treatments, and case study examples.