Selection Categories

There are many locations at which a roundabout could be selected as the preferred traffic control mode. There are several reasons why this is so, and each reason creates a separate selection category. Each selection category, in turn, requires different information to demonstrate the desirability of a roundabout. The principal selection categories will be discussed in this section, along with their information requirements.

A wide range of roundabout policies and evaluation practices exists among operating agencies within the U.S. For example, the Florida Department of Transportation requires a formal “justification report” to document the selection of a roundabout as the most appropriate traffic control mode at any intersection on their State highway system. On the other hand, private developers may require no formal rationalization of any kind. It is interesting to note that the Maryland Department of Transportation requires consideration of a roundabout as an alternative at all intersections proposed for signalization.

It is reasonable that the decision to install a roundabout should require approximately the same level of effort as the alternative control mode. In other words, if a roundabout is proposed as an alternative to a traffic signal, then the analysis effort should be approximately the same as that required for a signal. If the alternative is stop sign control, then the requirements could be relaxed.

The following situations present an opportunity to demonstrate the desirability of installing a roundabout at a specific location.