What is the Difference between a Rotary & a Roundabout?

> Roundabout FAQ > CCRPC Roundabout Projects & Information

For example, here is an aerial image of a Rotary:


View Larger Map

This is what it looks like on the ground:


View Larger Map

For example, here is an aerial image of a Roundabout:


View Larger Map

This is what a Roundabout looks like on the ground:


View Larger Map

 

The primary difference between a Roundabout and a Rotary is in its Size:

  • The greater size and expanded geometry of the Rotary allows for much higher speeds, which in-turn allows for higher injury and fatality rates during crashes.

  • The Rotary example (above) has two lanes allowing for "multi-lane weaving", which is an additional traffic phenomenon associated with higher crash rates.
This image is of a conversion of a Rotary into a Roundabout in Kingston, NY, off of I-87. Here the size difference between the two traffic devices is clearly indicated; where an approximate rotary diameter is greater than 600 feet, an approximate roundabout diameter is less than 300 feet.