The above Louisiana Department of Transportation and Development Public Service Announcement (PSA) video on driving through a roundabout.
by KAREN LAGRANGE COX
Roundabouts are circular intersections used for traffic management instead of traffic lights or stop signs. Vehicles circulate around a central island, yielding to traffic already within the roundabout before entering.
Roundabouts are used for various reasons, including safety priority, efficiency, and sustainability. They also accommodate the needs of various road users and enhance the built environment.
Some of the considerations for roundabouts are that they require more land than traffic lights or stop signs, that the initial cost for a roundabout is usually a higher investment than for the traffic lights and stop signs, and that there are costs for landscape maintenance.
While roundabouts may be beneficial, traffic lights may also benefit traffic management, including offering clearer guidance for drivers, controlling traffic flow, and requiring less land.
Some considerations for traffic lights include the potential for traffic congestion, dependency on power supply, malfunction, installation costs, and regular inspections.
The following questions and answers on roundabouts are from the Louisiana Department of Transportation and Development website. [source]
What is a roundabout?
- Roundabouts are one-way, circular intersections designed to improve safety and efficiency for motorists, bicyclists, and pedestrians.
- In a roundabout, traffic flows counterclockwise through a center island.
- A roundabout redirects conflicting traffic, such as left turns, which may cause crashes at traditional intersections because drivers enter and exit the roundabout through a series of right-hand turns.
What are the advantages of roundabouts?
- A well-designed roundabout can improve an intersection’s safety, operations, and aesthetics.
- Greater safety is achieved primarily by slower speeds and the elimination of more severe crashes. Smooth-flowing traffic with less stop-and-go than a signalized intersection improves traffic operation. The opportunity for more landscaping and less pavement enhances aesthetics.
What do statistics from the Federal Highway Administration (FHWA) say about roundabouts?
- Roundabouts may save lives by reducing fatalities by up to 90%.
- Roundabouts may reduce injury crashes by up to 76%.
- Roundabouts may reduce pedestrian crashes by up to 30% to 40%.
- Roundabouts create up to 75% fewer conflict points than a four-way intersection. Conflict points are any point where the paths of two vehicles through or turning diverge, merge, or cross.
- Roundabouts save money by:
- Reduces road electricity and maintenance costs by an average of $5,000 annually.
- Eliminates the costs to install and repair signal equipment.
- Provides a 25-year service life compared to the ten-year service life of signal equipment.
- Roundabouts provide environmental benefits by:
- Reduces vehicle delay and the number and duration of stops compared with signalized intersections, thus decreasing fuel consumption and carbon emissions. Fewer stops and hard accelerations mean less time idling.
How are modern roundabouts different than traffic circles and rotaries?
- Modern roundabouts are significantly different from older-style traffic circles and rotaries in how they operate and are designed. Rotaries and traffic circles may have two-directional flow and are typically much larger than the modern roundabout.
- The compactness of a modern roundabout helps keep speeds low and makes it easier for drivers to stay oriented and judge the speed of the vehicles before entering the roundabout.
- Modern roundabouts require entering traffic to yield, not merge at all entries. Meanwhile, traffic circles and rotaries may require circulating traffic to yield to entering traffic.
What are the general principles of using a roundabout?
- Think of roundabouts as a series of “T” intersections, where entering vehicles yield to one-way traffic coming from the left. A driver approaching a roundabout must slow down, stop, or yield to traffic already in the roundabout and yield to pedestrians in the crosswalk.
- Then, it’s simply making a right-hand turn onto a one-way street.
- Once in the roundabout, the driver proceeds around the central island and makes the necessary right-hand turn to exit.
Can roundabouts accommodate larger vehicles?
- Yes. Roundabouts are designed to accommodate vehicles with a large turning radius such as buses, fire trucks, and eighteen-wheelers. Roundabouts provide an area between the circulatory roadway and the central island, known as a truck apron, over which the rear wheels of these vehicles can safely track.
