MPC Research Reports
Report Details

Title:	Evaluation of Advance Warning Signals on High Speed Signalized Intersections
Authors:	Peter T. Martin, Vikram C. Kalyani, and Aleksandar Stevanovic
University:	University of Utah
Publication Date:	Nov 2003
Report #:	MPC-03-155
Project #:	MPC-233
TRID #:	00980585
Keywords:	detection and identification systems, dilemma zone, driving, signalized intersections, speed, stopping, traffic signals, warning signals

Abstract

UTL compared the intersections with an Advanced Warning System (AWS) to an intersection without AWS. They found that the AWS in St. George was not effective in reducing the number of drivers in DZs. Although 90% of drivers responded positively by reducing their speed when the signal was flashing, most of them reserved their decision to stop or proceed until they were close to the intersection. Speeds were reduced by an average of 5 to 10 mph. They were reduced less if drivers could see that the traffic light at the intersection was still green. St. George had 1.15% more vehicles in the DZ than the control intersection. The AWS setup at Brigham City was effective in reducing vehicles in the DZ. It had 1.4% fewer vehicles in the DZ than the Logan intersection. The effectiveness of AWS in Brigham City may be attributed to its combined AWS+AD setup. Because the research results did not yield conclusive results on the effectiveness of AWS systems, UTL recommends an intensive study at potential AWS locations before any future installations. UTL also recommends modifying the AWS system at St. George to improve its effectiveness.