Injury accidents were studied at 150 junctions and roundabouts before and after the installation of single or multiple islands, kerbed or unkerbed. 132 of these, considered separately, were previously governed by 30 or 40 mile/h speed limits with (a) priority control, (b) traffic signals, or (c) roundabouts. Type (a) 88 sites, had statistically significant reductions of 34 and 46 per cent in all injury and in fatal plus serious injury accidents respectively whether unkerbed sites were included or not. Type (b) 13 sites, all types combined, showed a statistically significant decrease in fatal plus serious accidents of 62 per cent. Type (c) 31 sites all kerbed. All types except single kerbed island sites with 3 arms showed a statistically significant increase of 91 per cent for all accidents and rather more for fatal plus serious especially when 2 multiple systems were included (200 per cent). accidents involving two-wheeled motor vehicles at type a sites, and those involving pedal cycles at type c sites, expressed as proportions of the total, were significantly reduced. In higher speed limit zones the changes in all accidents at a few sites, type (a) - 10 sites and (c) - 8 sites, were statistically significant and gave indications endorsing the results above. (Author/publisher)
Abstract