LEFT TURN SIGNAL WARRANTS FOR ARIZONA

A warrant was developed to choose the appropriate type of left turn signal phasing: permissive, exclusive/permissive, or exclusive. Time-lapse photography was used to observe volume and delay data at a total of six arterial-arterial signalized intersections in the Phoenix metropolitan area. From the time-lapse film, data on volume, number of vehicles stopping, total delay, average delay per stopped vehicle, and average delay for all vehicles was obtained for each turning movement. The effect of the type of left turn signal phasing onleft turn delay and through delay was analyzed. A three year history of Accident rates for the three types of left turn phasing were also reviewed. The developed warrant chooses the type of left turn phasing based on left turn volume, opposing volume, number of opposing lanes, cycle length, approach speed, sight distance restrictions, and accident history. (Author)