New Study by Arizona State University Reveals Some Roundabouts Increase Number of Crashes in Arizona

Posted by Shawn B. Hamp | Jul 19, 2017 | 0 Comments

Ask Arizonans how they feel about roundabouts, and you'll get a variety of opinions. However, whether state residents like them or not, they have likely and frequently dealt with them. There are approximately 80 one and two-lane roundabout sites in the state. These sites were built in an effort to deter car collisions and reduce delays. But a new study conducted by Arizona State University has concluded that they may be actually causing accidents for state motorists.

According to the study, the projected safety of a roundabout boils down to how many lanes it contains. Single-lane roundabouts effectively decreased the rates of accidents by 18%, while simultaneously decreasing the number of injuries by 44%. Researchers discovered that two-lane roundabouts, however, had a contrasting effect on the rates of accidents. The study found that while injuries significantly dropped with the implementation of two-lane roundabouts, the collision rate increased by more than a whopping 60%.

Lead researcher of this study and ASU professor, Michael Mamlouk, said that the results were alarming.But he says that he understands why accidents are occurring so frequently on two-lane roundabout sites.

A study by ASU found that while injuries significantly dropped with the implementation of two-lane roundabouts, the collision rate increased by more than a whopping 60%.

“People are not familiar with how to use roundabouts,” Mamlouk said. “That's the main thing- they don't know which lane to use. When they introduced traffic signals in the 1920s, it took people several years to get familiar with the three-color system and understand the rules of the traffic signal. I am sure people will get familiar with roundabouts with time and experience.”

Although there are some roundabouts in the state, they are relatively new. Many of the state's roundabouts were constructed within the last 10 years. Mamlouk says that when the public begins using them correctly, these accident rates will drastically decrease.

“Instead of stopping at the stop sign or at the red light when no other vehicles are at the intersection, roundabouts allow motorists to proceed with caution without stopping, allowing for free-flow movement,” he said. “Reducing stopping has the benefit of increasing the intersection capacity and reducing traffic delay and greenhouse gas emission.”

In addition to the public's incorrect use of these sites, Mamlouk also emphasized that constructing roundabouts in the right conditions makes all the difference when it comes to decreasing collision rates. When roundabouts are poorly placed, they are likely to heighten traffic congestion, which in turn increases accidents in that area. However, when they are properly placed, there is an apparent improvement. As of now, Mamlouk and his fellow researchers are presenting their findings to public officials in order to further improve the placement of roundabouts.

The study also comes in the wake of a fatal crash involving a young Phoenix wrong-way driver by the name of Keaton Allison. The collision was caused by Allison's inability to properly operate her vehicle in a two-lane roundabout. The crash claimed the lives of three people. 

Experienced Arizona Traffic Attorneys

If you are in need of legal counsel for any traffic-related incident, you should consult with a skilled legal professional who is well-versed in state traffic law. Contact the Law Offices of Shawn Hamp today for a consultation.

About the Author

Shawn B. Hamp

President and lead counsel for The Hamp Law Offices, LLC (An Arizona Professional Corporation), Shawn Hamp has practiced law for more than 15 years with an emphasis in criminal law. An experienced trial attorney, Mr. Hamp has been lead counsel in hundreds of criminal trials and court...


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