A roundabout, in general, is a circular intersection in which traffic travels counterclockwise around a central island and entering traffic yields to circulating traffic. Geometric features slow traffic at the intersection. There are four classifications of roundabouts: mini-roundabouts, compact roundabouts, single-lane roundabouts, and multilane roundabouts (see ). Mini and compact roundabouts are two types of reduced-diameter roundabouts with traversable features. While mini-roundabouts have a fully traversable center island and may have traversable splitter islands, compact roundabouts have a combination of traversable elements but do not provide a fully traversable center island. See for the varying typical diameters for the four classifications of roundabouts.

Roundabouts have been demonstrated to significantly reduce the number of severe crashes at intersections, improve Level of Service (LOS), and increase capacity. TxDOT has adopted as the primary source for roundabout design guidelines. The information contained in this section of the RDM is considered a companion guide to .