Over more than 17 years, the Regional Transportation Authority has delivered many transportation improvements to the greater Tucson metropolitan area through its 20-year plan voters approved in 2006.
These include reducing congestion, improving mobility options (bicycle and pedestrian facilities), improving safety, and expanding transit options. The RTA also has delivered enormous economic benefits totaling billions of dollars through project-related construction employment and post-construction private sector investments in improved areas.
Something we don’t often talk about, however, is the adoption of new and innovative applications when looking for solutions to improve traffic flow through the use of advanced traffic control options including how busy intersections throughout the region are designed.
“Because of various factors such as the age of roadways, dynamic traffic patterns, along with constrained locations, we have had to seek creative solutions to some of the region’s most challenging intersections,” said Rick Ellis, director of transportation services at Pima Association of Governments.
Some of these innovative approaches to improving intersections and other traffic controls employed in RTA projects include:
- Indirect left turns: These unconventional left turns direct motorists through an intersection to a signalized left U-turn where drivers then make a right turn to merge onto the new travel direction. Indirect left turns improve safety and traffic flow by delivering fewer delays and expediting travel times compared to the direct left turn. Indirect left turns are located at Ina and Oracle roads; Grant and Oracle roads; Grant Road and Stone Avenue; and Grant Road and First Avenue. An additional indirect left turn is planned for Grant Road and Alvernon Way. A variation on the indirect left turn also was used in the Valencia Road, Alvernon Way to Kolb Road, improvement project for eastbound left turns.
- Jughandle: This unique configuration was installed at the intersection of La Cholla Boulevard and Magee Road. The jughandle allows motorists to avoid a multi-phase left turn at an acute angle from northbound La Cholla onto westbound Magee. Instead, traffic continues northbound through the intersection then makes a right turn onto the jughandle-shaped loop that exits onto westbound Magee.
- Braided weave: This innovative design was constructed at the east-side frontage road at Continental Road and Interstate 19 in Green Valley. The design allows for eastbound and westbound traffic on Continental to turn south onto the frontage road, which goes beneath a section of the I-19 offramp before realigning with the frontage road in a two-way route.
- Roundabouts: Roundabouts are a highly effective way of improving intersection safety, congestion and operations. Rather than encountering multiple points of potential conflicts that can be encountered at a traditional intersection, roundabouts offer motorists, pedestrians and bicyclists safer and more controlled condition.
These and other innovative approaches to intersection configurations were not simply efforts to adopt new or unusual designs for the sake of novelty. Rather, challenges such as spatial limitations or asymmetrical roadway alignments or heavy traffic flows with regular changing patterns in these areas required creative solutions.
“The RTA has worked closely with jurisdictions to research and adopt innovative traffic control configurations,” Ellis said. “These are tried and tested technologies that have demonstrated in other communities to improve the overall intersection performance significantly.”