TRAFFIC FLOW ON GRADIENTS ON DIRECTIONAL CARRIAGEWAYS

VERKEHRSABLAUF AN STEIGUNGSSTRECKEN VON RICHTUNGSFAHRBAHNEN

IN THE DESIGN PROCEDURE DESCRIBED IN SPECIFICATIONS RAL-Q 73 THE TYPE OF TRAFFIC FLOW ON GRADIENTS HAS A MARKED INFLUENCE ON THE CAPACITY OF ROADS. THE DECREASE IN CAPACITY IN RELATION TO THE TYPE OF GRADIENT AND THE PROPORTION OF LORRIES NEEDS TO BE PROVED. IN PARTICULAR ATTENTION IS TO BE PAID TO LONGITUDINAL GRADIENT AND LENGTH OF GRADIENT, NUMBER OF LORRIES BY CAPACITY, WEIGHT, VEHICLE LENGTH, DEGREE OF LOADING, ETC. IN ESTABLISHING CAPACITY LIMITS FOR INDIVIDUAL ROAD SECTIONS THE QUALITY OF THE TRAFFIC FLOW HAS TO BE TAKEN INTO ACCOUNT. AS WELL AS FOR UPHILL GRADIENTS STUDIES ALSO HAVE TO BE CARRIED OUT ON DOWNHILL GRADIENTS, AS HERE TOO IN MANY CASES LORRIES HAVE TO TRAVEL AT DECREASED SPEED. TRAFFIC FLOW ON THOSE SECTIONS OF ROAD WHICH CONNECT WITH THE RISING OR DESCENDING GRADIENT ALSO HAS TO BE CONSIDERED. WORK WHICH HAS BEEN CARRIED OUT HITHERTO IN THIS FIELD DOES NOT PROVIDE A BASIS FOR SOLVING THE PROBLEM. THIS WORK HAS CONCENTRATED ON LORRY DESIGN WITHOUT CONSIDERING THE MIX OF DIFFERENT TYPES AND SIZES OF LORRIES, AND ALSO DID NOT CONSIDER RECENTLY INTRODUCED CONTROLS ON LORRY CAPACITY.