Frequently asked questions

No, a modern roundabout is not a four-way stop. Both intersections are what the engineering community calls a “method of moving traffic,” but four-way stops require all traffic to stop prior to entering the intersection. Modern roundabouts require motorists to yield at entryways. All traffic entering a modern roundabout must follow the golden rule of the modern roundabout: Never merge. Here are some other differences between roundabouts and four-way stops.

• Four-way stops yield to the right, while roundabouts yield to the left (similar to a right turn at a red light).
• Traffic in a modern roundabout circulates counterclockwise.
• Motorists coming from different directions take turns in a first-come-first-served order at a four-way stop. This is not the case with roundabouts, where each driver chooses a safe gap to enter.

Many traffic circles require circulating vehicles to grant the right of way to entering vehicles and can be very large or very small. They can operate at higher speeds and often require motorists to move from one lane to another.

Modern roundabouts include improvements such as yielding to as opposed to merging with circulating traffic, deflection at entry and low-speed entry by design.

The Arizona Department of Transportation manages implementation of the Arizona STSP and is a primary stakeholder as are the Arizona Department of Public Safety, Arizona Department of Health Services, Governor’s Officer of Highway Safety, Federal Highway Administration, National Highway Traffic Safety Administration and Federal Motor Carrier Safety Association. Hundreds of other stakeholders, representing municipalities, law enforcement, emergency responders, hospitals and health services providers, safety organizations, and more serve on Emphasis Area teams.

Every year, preventable crashes result in hundreds of fatalities and thousands of serious injuries on Arizona roadways. The purpose of the STSP is to direct transportation-project investment decisions and assure best practices are adopted to achieve a significant reduction in transportation related fatalities and serious injuries on all public roadways.

Based on the most recent analysis of statewide crash data, Arizona has identified five emphasis areas. These emphasis areas are a required component of any STSP and help direct resources, focus implementation efforts, and organize emphasis area teams. The five emphasis areas are: Highway Safety (Behavior-Related), Intersections, Lane Departure, Pedestrians and Safety-Related Data.

A Strategic Traffic Safety Plan (STSP) is a statewide, coordinated plan that provides a comprehensive framework for reducing fatalities and serious injuries on all public roads. The STSP is developed by the Arizona Department of Transportation in cooperation with local, regional, state, federal, tribal, non-profit and private-sector safety stakeholders. The STSP is a data-driven, multiyear plan that establishes statewide goals and objectives and identifies Emphasis Areas that must be addressed to reduce traffic fatalities and serious injuries. The plan outlines feasible strategies and action steps or countermeasures to address the Emphasis Areas through integration of the 4 E’s of transportation safety: Engineering, Education, Enforcement and Emergency Medical Services.