ROUNDABOUTS: THE NEW DUTCH GUIDELINES

In 1998, a new regulation on roundabouts was introduced in The Netherlands to improve safety on roundabouts. It provides more uniformity in right of way rules, design, and equipment, and has three main guidelines about right-of-way rules. This paper discusses road safety at roundabouts, the capacity of roundabouts and the uniform layout design of individual roundabouts, together with various design elements. Several studies of safety at roundabouts have been conducted during recent years. They have been aimed mainly at: (1) the safety of roundabouts compared with other junction types; (2) the safety of cycle lanes as opposed to segregated cycle tracks; (3) cyclists having or not having right of way; and (4) the relationship between the safety and design of roundabouts. Appropriate capacity for a single-lane roundabout is 20,000-25,000 vehicles per 24-hour day. For a two-lane roundabout with single-carriageway approaches, it is 22,000-30,000 per day. For a two-lane roundabout with dual-carriageway approaches, it is 35,000-40,000 per day. The paper discusses the design of a roundabout as an example. When designing the layout of a roundabout, particular attention should be given to its external and internal radii, carriageway width, raised sloping lane, crossings for slow traffic, and slip roads.