Magic Roundabout (High Wycombe) whilst the A404 goes south to Marlow and Maidenhead. Magic Roundabout (High Wycombe) The Magic Roundabout in High Wycombe, Buckinghamshire, England, is similar to the roundabouts with the same name in Swindon and other places. It is located on the junction of the A40 and A404. The junction is the second meeting point of the two roads, they interchange at the start of the A404 in Marylebone, London, with the A40 forming the Westway. The two roads follow different routes to reach Wycombe, the A40 coming via Beaconsfield and the A404 via North London and Amersham. From the roundabout, the
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",