Impact of Left-Turn Phasing on Older and Younger Drivers at High-Speed Signalized Intersections, 2004

(2004) Impact of Left-Turn Phasing on Older and Younger Drivers at High-Speed Signalized Intersections, 2004. Transportation, Department of


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Several recent studies have demonstrated differences in safety between different types of left-turn phasing—protected, permitted, and protected/permitted phasing. The issue in question is whether older and younger drivers are more affected by a particular type of left-turn phasing at high-speed signalized intersections and whether they are more likely to contribute to a left-turn related crash under a specific type of left-turn phasing. This study evaluated the impact of different types of left-turn phasing on older and younger drivers at high-speed signalized intersections in Iowa. High-speed signalized intersections were of interest since oncoming speeds and appropriate gaps may be more difficult to judge for older drivers and those with less experience. A total of 101 intersections from various urban locations in Iowa with at least one intersecting roadway with a posted speed limit of 45 mph or higher were evaluated. Left-turn related crashes from 2001 to 2003 were evaluated. Left-turn crash rate and severity for young drivers (14- to 24-year-old), middle-age drivers (25- to 64-year-old), and older drivers (65 years and older) were calculated. Poisson regression was used to analyze left-turn crash rates by age group and type of phasing. Overall, left-turn crash rates indicated that protected phasing is much safer than protected/permitted and permitted phasing. Protected/permitted phasing had the highest left-turn crash rates overall.

Item Type: Departmental Report
Keywords: Adults, Aged drivers, Crash rates, Drivers, Exclusive permissive phasing, Exclusive phasing, Highway safety, Highway traffic control, Left turn phase, Left turns, Permissive phasing, Signalized intersections, Traffic crashes, Traffic safety, Traffic signals, Young adults
Subjects: Transportation
Transportation > Traffic safety
Transportation > Research
Transportation > Drivers
ID Code: 21069
Deposited By: Iowa DOT Library
Deposited On: 17 Dec 2015 13:09
Last Modified: 17 Dec 2015 13:09