01023216

Component

In December 2004, in response to a formal request from the North Carolina Department of Transportation (NCDOT), the North Carolina Section Institute of Transportation Engineers (NCSITE) announced a Task Force to investigate and recommend a practice for determining yellow change and all-red clearance intervals at signalized intersections in North Carolina. Following receipt of the Task Force’s recommendation, on July 15, 2005, the State Intellignet Transportation System (ITS) and Signals Engineer issued a memo announcing that the new practice would go into effect as of August 1, 2005. While published methods exist, most notably from ITE, there is not a national standard, nor is there a legally binding practice, such as those normally associated with the Federal Highway Administration (FHWA) Manual on Uniform Traffic Control Devices (MUTCD). After a description of the Task Force composition and process, this paper reviews the recommended practice, along with the key factors considered by the Task Force during the process. Of critical interest to the Task Force was the mitigation of excessive yellow change and all-red clearance intervals, as wider facilities and other design elements have been resulting in ever-lengthening intervals. While the method for calculating yellow change intervals follows the “ITE formula,” the method for calculating all-red clearance intervals includes modifications to the ITE formula, resulting in lower all-red clearance intervals. Other topics discussed include: consideration of enforcement devices, like red light cameras; determination of clearance distance, appropriate left turn speeds, time to conflict point; and mitigation of excessive all-red clearance intervals.

01020180

06-1099

English

15p

2006

Transportation Research Board 85th Annual Meeting

CD-ROM

Figures (3) ; References (20) ; Tables (3)

Clearance interval (Traffic signal cycle); Red interval (Traffic signal cycle); Red light running; Signalized intersections; Traffic control devices; Yellow interval (Traffic signal cycle)

Manual on Uniform Traffic Control Devices; North Carolina Department of Transportation

Safety design; Safety standards

North Carolina

Highways; Operations and Traffic Management; Safety and Human Factors; I70: Traffic and Transport

Transportation Research Board Annual Meeting 2006 Paper #06-1099

TRIS, TRB

Mar 3 2006 10:35AM