Distinguishing Roundabouts from Other Circular Intersections

Since the purpose of this guide is to assist in the planning, design, and performance evaluation of roundabouts, not other circular intersections, it is important to be able to distinguish between them. Since these distinctions may not always be obvious, the negative aspects of rotaries or neighborhood traffic circles (hereafter referred to as “traffic circles”) may be mistaken by the public for a roundabout. Therefore, the ability to carefully distinguish roundabouts from traffic circles is important in terms of public understanding.

How then does one distinguish a roundabout from other forms of circular intersection? Exhibit 1-5 identifies some of the major characteristics of roundabouts and contrasts them with other traffic circles. Note that some of the traffic circles shown have many of the features associated with roundabouts but are deficient in one or more critical areas. Note also that these characteristics apply to yield-controlled roundabouts; signalized roundabouts are a special case discussed in Chapter 8.

In addition to the design elements identified in Exhibit 1-5, roundabouts often include one or more additional design elements intended to enhance the safety and/ or capacity of the intersection. However, their absence does not necessarily preclude an intersection from operating as a roundabout. These additional elements are identified in Exhibit 1-6.