What Are The Advantages of Roundabouts for Traffic Control?


Here’s another video tip from our “How To” series. The transcript is below:

Hi, W&A Engineering here, your local Athens, Georgia based engineering firm, here again with another tip from our “How to” series. One of our specialties is traffic engineering and today I’ll be talking about the advantages of using roundabouts for traffic control.

OK, let’s get started…

So, what is a Roundabout?

Roundabouts, like traffic signals and stop signs, control the flow of traffic at roadway intersections. Modern roundabouts have several characteristics that differentiate them from other circular roadway features such as traffic circles and rotaries, which allow high vehicle speeds, require large amounts of land, and require circulating traffic to yield to incoming traffic. Unlike older circular roadways, modern roundabouts have channelized approaches to separate opposing traffic at the entry and exit points, roadway curvature that promotes lower vehicle speeds, counterclockwise circulation around a central island to eliminate left turns and reduce the number of vehicle conflict points, and require entering traffic to yield to circulating traffic.

What are the 7 Advantages of Using a Roundabout for Traffic Control?

First, Safety

Modern roundabouts eliminate through and left turn movements and thus reduce the number of vehicle conflict points, the angle of impacts, and the resulting severity of injuries and number of fatalities when compared to those associated with stop-controlled and signal-controlled intersections.

Second, Functional Performance

Modern roundabouts do not require entering and existing vehicles to stop.  All approaches are yield-controlled which reduces delay and congestion. At stop-controlled and signal-controlled intersections, opposing and cross traffic is required to stop to allow the approach with the right-of-way to proceed through the intersection, while at a modern roundabout, vehicles from all four approaches may simultaneously enter the roundabout. During off-peak hours, vehicles entering the roundabout experience minimal delay as there are fewer vehicles to which the entering vehicles are required to yield; whereas, vehicles in signal-controlled intersections may sit through an entire signal cycle during the off-peak hours even when there is no cross traffic.

Third, Economic Impact

Modern roundabouts use less electricity and have fewer electrical components than traditional signalized intersections.  Equipment maintenance that is required for a traffic signal includes bulb replacement, routine upgrades and replacements, and software updates. The reduction in accidents that occur at roundabouts results in a reduction in economic and social costs related to property damage, physical injuries and fatalities.

Fourth, Environmental Impact

Since vehicles are not required to stop at the approach to a modern roundabout, idle time and stop and start movements are reduced when compared to traditional intersections. With these changes in vehicle operation patterns, users of the intersection will experience reduced noise and air quality impacts as well as reduced fuel consumption.

Fifth, Traffic Calming

Modern roundabouts are designed with specific geometric parameters that encourage drivers to reduce the operating speed of their vehicles. Signage at each approach to the roundabout limits the speeds of vehicles entering the intersection.

Sixth, Aesthetics

The central island and splitter islands provide landscape opportunities as well as serving as a unique roadway feature that can be used as a landmark or gateway feature for a region or neighborhood.

And seventh, Pedestrian Access

Pedestrian safety is provided at roundabouts by reducing vehicle operating speeds and providing pedestrian refuge in the splitter islands. The refuge areas allow pedestrians to focus on approaching vehicles from one-direction at each stage of the crossing.

There you have it! The top 7 advantages of traffic roundabouts…

Good luck in your traffic engineering projects, and if you’re ever in Athens, stop by and see us.

Until next time, all the best from W&A Engineering…