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Fitzpatrick, Brewer, Eisele, Zhang, Gluck, Levinson, and Iragavarapu 1 DEVELOPMENT OF LEFT-TURN LANE WARRANTS FOR UNSIGNALIZED INTERSECTIONS Kay Fitzpatrick,a Marcus A. Brewer,b William L. Eisele,c Yunlong Zhang,d Jerome S. Gluck,e Herbert S. Levinson,f and Vichika Iragavarapug Submitted to the Transportation Research Board 91st Annual Meeting, January 2012. TOTAL WORDS: 7475 equivalent (Words=5475, Tables=5(250)=1250, Figures=3(250)=750) ABSTRACT 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 some left-turn warrants have been updated, many agencies still use research performed by M.D. 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 crash 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 Kay Fitzpatrick, Ph.D., P.E. (corresponding author), Senior Research Engineer, Texas Transportation Institute, 3135 TAMU, College Station, TX 77843-3135, phone: 979/845-7321, fax: 979/845-6006, email: K-Fitzpatrick@tamu.edu b Marcus A. Brewer, P.E., Assistant Research Engineer, Texas Transportation Institute, 3135 TAMU, College Station, TX 77843-3135, phone: 979/845-7321, fax: 979/845-6481, email: m-brewer@tamu.edu c William L. Eisele, Ph.D., P.E., Research Engineer, Texas Transportation Institute, 3135 TAMU, College Station, TX 77843-3135, phone: 979/845-8550, fax: 979/845-6008, email: bill-eisele@tamu.edu d Yunlong Zhang,Ph.D., P.E., Associate Professor, Zachry Department of Civil Engineering, Texas A&M University, CE/TTI 301-G, 3136 TAMU, College Station, TX 77843-3136, email: yzhang@civil.tamu.edu e Jerome S. Gluck, PE, PTOE, Associate Vice President, U.S. Transportation Planning, AECOM, 605 Third Avenue, New York, NY 10158, phone: 212/973-2962, fax: 212/972-0832, email: Jerome.Gluck@aecom.com f Herbert S. Levinson, P.E., Consultant, email: hslevinson@aol.com g Vichika Iragavarapu, Assistant Transportation Researcher, Texas Transportation Institute, 3135 TAMU, College Station, TX 77843-3135, Phone: 979/845-7321, fax: 979/845-6006, E-mail: v-iragavarapu@ttimail.tamu.edu TRB 2012 Annual Meeting Paper revised from original submittal.
