BROOK HILL ROUNDABOUT, SHEFFIELD: A BEFORE-AND-AFTER STUDY

Observations were made of traffic delays and the 35 m diameter small-island layout was introduced. The before study covered the period prior to any alternation of the original roundabout layout, whilst the after study was carried out 8 months completion of the new roundabout traffic capacity experiment. The pattern of traffic movements through the intersection during both morning and afternoon peak hours and typical off-peak periods were recorded, as well as traffic delay during these periods. The results confirm that the increased capacity shown in observations has led to a reduction in delays to vehicles despite increases of 8 to 10 percent in the peak hour traffic volumes. Peak hour delays are estimated to have been reduced by some 3500 veh-hr per annum.