Abstract
This project focuses on protected-permitted left-turn phasing, including the different types of signal arrangements and indications, their benefits, and their drawbacks. Several previous studies were reviewed, and a number of agencies were contacted for information related to the operations of intersections with protected-permitted phasing. Twelve intersections in Sacramento County, California were analyzed using Synchro traffic analysis software to compare protected-only left-turn phasing with typical protected-permitted phasing. The analysis showed significant improvements in delay, especially with the left-turn movements benefitting from the protected-permitted phasing. Based on the available information, it can be shown that protected-permitted phasing increases traffic operational efficiency, decreases delay, reduces fuel consumption, and decreases emissions. Overall, the implementation of protected-permitted phasing can be beneficial when done properly by experienced traffic engineers. The twelve Sacramento County intersections that were analyzed as part of this project show that there is promise in the use of PPLT in the Sacramento area. Multiple intersections are estimated to experience significant operational improvements with PPLT based on the predictions of the traffic analysis software. Considering these results and the research conducted by sources cited in this report, the Sacramento County Department of Transportation should proceed with the implementation of PPLT.