01334161

Component

The purpose of this study was to investigate permissive left-turn right-angle crashes during a permissive phasing at intersections where protective-permissive five-section left-turn signals are operated in Northern Virginia. A five-section left-turn signal head provides protective left-turn phasing with a green arrow followed by permissive phasing with a green ball for left-turn vehicles. Five-year crash data from 2003 to 2007 and signal inventory data were used to form the study dataset. A panel negative binomial regression model was used to develop a safety performance function and to find out factors affecting the occurrence of permissive left-turn right-angle crashes. Speed limits, the number of lanes from opposing approaches, and average annual daily traffic (AADT) were related to annual total crash frequency. AADT and the number of lanes from opposing approaches were found to be influential. Three or more opposing lanes were found to have differential effects on such crashes compared to one or two lanes at intersections under operation with a five-section left-turn signal head. The study findings might have implications for traffic engineers in determining whether an existing protective-permissive five-section signal head should be converted to a protected-only signal head considering potential safety consequences.

01329018

11-2302

English

11p

2011

Transportation Research Board 90th Annual Meeting

DVD

Figures (3) ; References (10) ; Tables (5)

Annual average daily traffic; Crash data; Crash rates; Left turns; Right angle crashes; Traffic crashes; Traffic safety; Traffic signals

Permissive left turn operations; Protected left turns

Northern Virginia

Highways; Operations and Traffic Management; Safety and Human Factors; I80: Accident Studies

Transportation Research Board Annual Meeting 2011 Paper #11-2302

TRIS, TRB

Feb 17 2011 6:07PM