U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
This figure is a diagram depicting the characteristics of a roundabout. It shows a roundabout in the center of the figure at the intersection of a four-lane road (two lanes each way separated by an island) running north-south and a two-lane road (one lane each way separated by an island) running east-west. Six items are depicted in the figure:
This figure shows two diagrams: a traditional intersection with four legs (with the caption "traditional intersection") and a roundabout with four legs (with the caption "roundabout"). The caption over the entire figure reads "With roundabouts, head-on and high-speed right angle collisions are virtually eliminated."
Each figure shows the paths that left turns, right turns, and through movements make through each intersection. Where paths cross, a red dot has been placed; the red dot has the legend "potential vehicle conflict point." The traditional intersection has 32 red dots, 16 that involve movements crossing one another (representing potential head-on and high-speed right angle collisions) and 16 that involve merging or diverging conflicts. The roundabout has 8 red dots, all of which represent merging or diverging conflicts.
This figure is a diagram of a roundabout with four two-lane roads (one lane each way separated by an island) approaching it: one each from the top, bottom, left, and right and single entering and exiting lanes on all legs. It has the caption "Tips for safely walking and biking through a roundabout."
The diagram has a set of purple arrows illustrating a path for how pedestrians can safely walk around the roundabout to get from the northeast corner of the intersection to the southwest corner. The path starts at the east end of the crosswalk across the north leg, passes to the splitter island dividing the north leg's exit and entry (where an icon of a pedestrian is shown), and then passes to the west end of the crossing across the north leg. The path then curves along a sidewalk that is separated from the roundabout curb by a green landscaping buffer until it reaches the crosswalk across the west leg. The path then proceeds to the splitter island in the west leg and then to the south end of the crosswalk. The path has the caption "Walk around the outside; don't cross through the middle."
The figure also depicts two paths for cyclists. One set of red dotted lines depicts the safe path for a cyclist riding his/her bike by using the travel lane as a vehicle. This is shown as a path starting from the south leg. The path enters the roundabout and then splits into two paths, with one depicting a through movement to the north and one depicting a right turn to the east (all in travel lanes). A second set of red dotted lines depicts a cyclist walking his/her bike along the sidewalk. This is shown as a path starting from the sidewalk on the east side of the south leg. The path proceeds north along the sidewalk and curves along the perimeter of the roundabout to the south side of the east leg. At the crosswalk on the east leg, the path splits into two, with one using the crosswalk across the east leg and one continuing to follow the sidewalk to the east. The caption reads "Ride your bike as a vehicle or walk your bike as a pedestrian."
Below the figure, a caption reads "Research is ongoing on additional treatments and design considerations to address the needs of visually impaired pedestrians."