Warrants for the installation of separate left-turn lanes were developed. Literature was reviewed, and policies and practices in other states were surveyed. Accident analyses of locations with and without separate left-turn lanes were conducted. Computer simulation was used to determine the relationship between and among traffic delay and load factor and traffic volume, percent left-turns, cycle length, and cycle split. The relationship between left-turn accidents and conflicts was investigated.

Warrants were developed involving the following three general areas: (1) accident experience, (2) volumes (based on delay), and (3) traffic conflicts.

Report Date


Report Number

No. 526

Digital Object Identifier



The contents of this report reflect the views of the author who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Bureau of Highways. The report does not represent a standard, specification, or regulation.