this report describes an experiment carried out during october 1972 at the five-arm brook hill roundabout, sheffield, to determine the capacities of two new roundabout designs, and to compare them with the original conventional roundabout; the junction has an inscribed circle diameter of 75 m. the new layouts tried were a ring junction design and a mini-roundabout. the ring junction consists of five mini-roundabouts and was designed to overcome some of the problems associated with right-turning traffic. two versions of the mini-roundabout were tried with different sizes of central island and corresponding adjustments to the entry arrangements. the capacity of the ring junction was about 7 per cent higher than the original roundabout, and the two mini-roundabouts gave overall increases of 17 per cent and 28 per cent respectively for the designs with 20 m and 35 m diameter islands. the operation of these layouts is discussed. (a).

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