Intersection Safety Case Study Summary Continuous Green TIntersections

Intersection Safety Case Study Summary Continuous Green T-Intersections A Colorado Success Story FHWA-SA-09016

The Challenge • Angle crashes are among the most severe crashes that occur at intersections, including T-intersections. • Limited stopping sight distance is a common reason. • Colorado Department of Transportation (CDOT) sought an intersection design treatment to reduce the number and severity of crashes at signalized T-intersections.

Solution Continuous Green T-intersections (CGT): • Main line through traffic passes through without stopping (the top side of the “T”), denoted with continuous green signal • Dedicated acceleration and deceleration lanes provided for leftturning movements • Concrete median and pavement markings provide lane separation

Technical Data • Locations: – 2 high-crash intersections in Colorado • Speed Limits: – Ranged from 35 mph to 50 mph • Implementation Cost: – $300, 000 per intersection including the new signals and the raised median work • Implementation Time: – 3 months per intersection • Implementation Issues: – CDOT experienced no implementation issues with this countermeasure.

Results at Treated Intersections • Average Crash Reductions: – 96. 8% reduction in angle crashes per year – 70% reduction in injury crashes per year – 60% reduction in total crashes per year

For More Information • Visit FHWA’s intersection safety web site to download this and other case studies highlighting proven intersection safety treatments from across the country: http: //safety. fhwa. dot. gov/intersection • Or Contact: Zane Znamenacek Region 3 Traffic Operations Engineer, Colorado Department of Transportation Phone: (970) 683 -6278 E-mail: zane. znamenacek@dot. state. co. us Ed Rice Intersection Safety Team Leader, FHWA Office of Safety Phone: (202) 366 -9064 E-mail: ed. rice@dot. gov