SPEED PROFILES AT SLOW POINTS ON RESIDENTIAL STREETS. CIVIL ENGINEERING WORK PAPER

Speed control on residential streets is an important objective for traffic management by local government authorities. A wide range of measures and devices have been proposed and a few of these (eg, road humps) have been quantitatively tested and evaluated for their effectiveness and performance. This paper describes a pilot survey aimed at evaluating the family of 'diagonal slow point' devices used by many municipalities for speed control on local streets. Vehicle speed profiles around four slow points were measured, and the speed reduction effects analysed. The data permit the performance of the devices to be assessed under a range of design parameter values and street environments. The results suggest that a device length of about 10 m with an angle of 30 degrees gives the optimum speed reduction effects. The qualifications on this result are that some measures may be needed to support the diversionary effect on vehicle trajectories, and that the effect of the device is seen only within a short, local 'zone of influence'. The experimental procedure derived from the pilot survey should be applicable in testing a wide range of device types. (TRRL/Author)