Magic Roundabout (Hemel Hempstead) a New Town the roads met in a simple junction which was then replaced by a standard roundabout. Constructed in 1973, the "Magic Roundabout" in Hemel Hempstead was voted the UK's second-worst roundabout in a 2005 poll held by an insurance company (the winner being its Swindon counterpart). In 2011 the roundabout was voted the best in Britain by motorists in a competition organised by a car leasing service. The original magic roundabout had six exits in total, with the British Petroleum building spanning "Marlowes", the road leading to the town centre, in the approximate position of the earlier railway
Roundabout Devices. Roundabouts are generally not appropriate for placement on motorway or freeway mainlines because the purpose of such facilities is to provide for uninterrupted traffic flow. However, roundabouts are often used for the junction between the slip roads (ramps in North America) and the intersecting road. A single roundabout, grade separated from the mainlines, may be used to create a roundabout interchange. This type of junction is common in the UK and Ireland. Alternatively, separate roundabouts also may be used at the slip road intersections of a diamond interchange to create what often is referred to as a "dumbbell interchange",