Summary

The modern roundabout is a one-way, circular intersection, designed to provide safe and effcient traffic flow. Not to be confused with older style traffic circles and rotaries, a modern roundabout utilizes "yield at entry" and special geometry to calm traffic, dramatically reducing injury accidents while improving traffic flow over standard signalized intersections. Delay is reduced due to the smooth flow of vehicles entering the roundabout. Roundabouts are much smaller in size than many of the traffic circles that were built 30-50 years ago.

Safety

The City of Hilliard believes safety is paramount and is committed to investing in solutions for a safer community.

Roundabouts are designed to move traffic through an intersection at a slower speed but steady rate, increasing safety and reducing delays. Two primary design features accomplish this goal:

• Drivers enter the roundabout facing a central island and yield to vehicles within the circulatory roadway, keeping weaving to a minimum
• Roundabout entrances and exits are curved to promote low traffic speeds

Traffic will circulate counterclockwise, passing to the right of a central island. Raised splitter islands will divide the roadway at entrances and exits. These splitters ensure that drivers travel in the intended path and separate opposing traffic. Splitter islands also improve pedestrian safety and provide spaces for aesthetic enhancements.

Roundabouts are safer for pedestrians than signalized intersections for a number of reasons:

• Slow vehicle speeds (20 – 25 MPH) at the crosswalks.
  
• Because the lanes approaching and leaving roundabouts are separated by splitter islands, pedestrians need only negotiate one direction of vehicular traffic at a time. Refuge is provided for pedestrians in the splitter island prior to crossing the outbound vehicular lanes.
  
• Two-lane roundabouts have 16 pedestrian/vehicle conflict points as compared to 28 or more for an equivalent signalized intersection depending on the number of lanes. Despite the use of "WALK" indicators at signalized intersections, crosswalks are still traversed by vehicles turning left and right on red, both movements causing the driver to focus on approaching vehicular traffic and not pedestrians in the crosswalk.
  
• Since crosswalks are only located at the approach/exit lanes and are set at least one car length back from the entrance to the circle, drivers do not have to split their attention between pedestrians and oncoming vehicular traffic.

Studies from around the world show that roundabouts typically reduce crashes by 40-60 percent compared to stop signs and traffic signals. They also reduce injury crashes by 35-80 percent and virtually eliminate incapacitating injury and fatal crashes. Two recent U.S. studies are consistent with these results.

Improved traffic flow through a modern roundabout means that fewer vehicles are idling at a congested intersection, reducing pollution and fuel consumption. Modern roundabouts also decrease ambient noise levels and provide an ideal location for aesthetic landscaping.