Samenvatting
The NAASRA design guide for roundabouts (1986) uses the results of a UK study into the relationship between the degrees of deflection for through movements and accident frequencies, as a basis for the concept that all roundabouts should be designed so that the speed of all vehicles within the intersection will be less than 50 km /h. A change in the method of measuring through radii paths to allow for lane switching, on two lane roundabouts, was found to improve the performance of the NAASRA side friction formula for determining through speeds.