Speed reducing measures

A new road classification for urban roads has been introduced in denmark. The basis of this classification is the road function and the desired speed - the reference speed - as the governing parameter. A prerequisite for making the road classification work in practice is, of course, that the reference speed is respected by the drivers. It is therefore necessary to use effective speed reducing measures such as humps and staggerings. As knowledge about the geometric design of these speed reducing measures was not available in denmark for reference speeds of 30 km/h, 40 km/h, 50 km/h, and 60 km/h, it was decided to acquire this knowledge through trials. Hump geometrics for both car and bus were determined. The types of humps chosen were the t hump (trapezoidal hump) and the c hump (circular hump). For each of the speeds - 30 km/h, 40 km/h, and 50 km/h - a geometric design was chosen which would give the driver a vertical acceleration of 0.7 G. The trials resulted in a new type of hump - the k hump - which at the same speed would expose the car driver and the bus driver to the same discomfort. The geometric design of staggerings were determined for the car, the bus, and the articulated vehicle, for reference speeds of 30 km/h, 40 km/h, 50 km/h, and 60 km/h, and for the free sight ranging from -1.0 M to 2.0 M. A video technique was used for determination of the wheel track (a).