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The Debate - Roundabouts vs. Traffic Lights Continues

Engineering StackExchange.com, a question and answer site for professionals and students of engineering, has many comments from those in favor of roundabouts who say that, among other things, they are safer than traffic light intersections. This claim, they say, has been scientifically proven. On the other hand, they say traffic light intersections are more space-inefficient.

The Federal Highway Administration Office of Safety identified roundabouts as a “Proven Safety Countermeasure because of their ability to substantially reduce the types of crashes that result in injury or loss of life. Roundabouts are designed to improve safety for all users, including pedestrians and bicycles.” 

According to data from the International Road Traffic Database, some six million traffic accidents occur each year in the U.S. Of these accidents, 40 percent happen in intersections. International Road Traffic says that intersections may be convenient and familiar for drivers, but their inherent design allows for a proliferation of high-speed, high-impact crashes. 

Traffic Signal: Pros and Cons (Sources: Arizona & Wyoming Departments of Transportation) 

Traffic signals are electrically operated traffic control devices that alternately direct traffic to stop and to proceed. The primary function of any traffic signal is to assign right of way to conflicting movements of traffic at an intersection, and it does this by: 

• Providing for the orderly movement of traffic.
• Increasing the traffic handling capacity of an intersection.
• Reducing the frequency and severity of crashes, particularly right angle or broadside crashes.
• Interrupting heavy traffic at intervals to permit other vehicles or pedestrians to cross. 

Traffic signals are not a solution for all traffic problems at intersections, and unwarranted signals can adversely affect the safety and efficiency of traffic by causing one or more of the following: 

• Excessive delay;
• Increased traffic congestion, air pollution and gasoline consumption;
• Disobedience of signals;
• Increased use of less-adequate streets to avoid traffic signals;
• Increased frequency of crashes, especially rear-end collisions. 

Roundabouts: Pros and Cons (Sources: Federal Highway Administration & RoundaboutsUSA) 

A roundabout is a type of circular intersection, but is quite unlike a neighborhood traffic circle or large rotary.  Roundabouts have been proven safer and more efficient than other types of circular intersections by the very nature of their construction. 

Counterclockwise Flow. Traffic travels counterclockwise around a center island. 

Entry Yield Control. Vehicles entering the roundabout yield to traffic already circulating. 

Low Speed. The curvature of roundabouts results in lower vehicle speeds, generally 15-25 MPH, throughout the roundabout. 

Roundabout controlled intersections can efficiently service traffic with decreased delay and greater efficiency than traffic signals. This is particularly true where traffic volumes entering the roundabout are nearly balanced on all legs and where there are a high number of left-turning vehicles. 

Roundabouts, however, do have their own limitations: 

• Steady-state entry headways are shorter at traffic signals because of the positive assignment of right-of-way. By using long cycle times to minimize the effects of startup lost time, it is possible under most conditions to achieve higher approach capacities.
• For very low-volume applications, TWSC (two-way stop control) and AWSC (all-way stop control) are easier and less expensive to implement.
• Since roundabout operation is not periodic, it is not possible to coordinate the operation of roundabouts on an arterial route to provide smooth progression for arterial flows.
• Roundabouts offer the least positive form of control. Each vehicle entering the intersection must yield to all traffic that has already entered, but they still experience less accidents than a comparable signal or stop control.
• Roundabouts impose a new form of traffic control that may not be familiar to motorists, but experience has found that drivers learn quickly how to drive in a roundabout. 

Therefore, roundabouts are not the solution to all traffic problems at all locations.  

“Any accident can be devastating. Contact our experienced team of attorneys if you or a loved one is involved in an accident as the result of another’s actions,” says Fort Myers Auto Accident Attorney, Randall Spivey of Spivey Law Firm, Personal Injury Attorneys, P.A. 

Fort Myers Auto Accident Attorney, Randall L. Spivey is a Board Certified Trial Attorney – the highest recognition for competence bestowed by the Florida Bar and a distinction earned by just one (1%) percent of Florida attorneys. He has handled over 2,000 personal injury and wrongful death cases throughout Florida. For a free and confidential consultation to discuss your legal rights, contact the Spivey Law Firm, Personal Injury Attorneys, P.A., in Lee County at 239.337.7483 or toll free at 1.888.477.4839, or by email to Randall@SpiveyLaw.com. Visit SpiveyLaw.com for more information. You can contact Spivey Law Firm, Personal Injury Attorneys, P.A.in Charlotte County at 941.764.7748 and in Collier County 239.793.7748.