THE SAFETY IMPLICATIONS OF SOME CONTROL CHANGES AT URBAN INTERSECTIONS

Injury accident data for a sample of New Zealand urban intersections were analysed. The data were arranged in monthly time series and collected from intersections both where control had changed and control had not changed during the study period. The analysis was designed to isolate the effect on safety of various changes in control from the effect of time trends and individual intersection characteristics. The changes in control considered were changes from give way signs, stop signs and no control to signals and small roundabouts. Signals and roundabouts appeared to reduce accidents at 4-leg junctions. At 3-leg junctions roundabouts appeared to reduce accidents while there was no hard evidence of any accident change associated with signals.