Magic Roundabout (Hemel Hempstead) 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 a former public house, called "The Plough Inn", which was between the junction of what is now Selden Hill and St Albans Road. It has also been known as the Moor End Roundabout as it is adjacent to the part of Boxmoor nearest the town. Before Hemel Hempstead became
Roundabout islands is 28 metre diameter ICD with a 4-metre diameter island. This threshold being driven primarily by vehicle geometry – which is globally relatively consistent – rather than driver behaviour, it is adopted in other jurisdictions too. Below this minimum size, the mini-roundabout prevails. After developing the offside priority rule, Frank Blackmore, of the UK's Transport Research Laboratory, turned his attention to the possibility of a roundabout that could be built at sites lacking room for a conventional roundabout. Mini-roundabouts can be a painted circle or a low dome but must be fully traversable by vehicles. Motorists can drive over