Magic Roundabout (Hemel Hempstead) viaduct. The BP building was found to be unstable due to defective reinforced concrete and the exit had to be closed. The building was demolished but the original route was not restored, although a newer side exit from the roundabout replaced the junction with Marlowes off a side road. Magic Roundabout (Hemel Hempstead) The "Magic Roundabout" in Hemel Hempstead, Hertfordshire, England, is the familiar name given to the Plough roundabout. The familiar name comes from the children's television programme, and is also used for a similar junction in Swindon and the M40 junction in Denham. The official name relates to
Roundabout priority over it (Traffic circle), but take it in turns to enter from each. Almost all of Jersey's roundabouts are of this type. In the Philippines, the term "rotunda" or "rotonda" is used in referring to roundabouts. The fundamental principle of modern roundabouts is that entering drivers give way to traffic within the roundabout without the need for traffic signals. Conversely, traffic circles typically require circling drivers to give way to entering traffic. Generally, exiting directly from an inner lane of a multi-lane roundabout is permitted, given that the intersecting road has as many lanes as the roundabout. By contrast,