Method for measuring road surface longitudinal profile

A longitudinal road surface profile measurement method for surveying a longitudinal irregularity condition in a road surface while moving a measurement vehicle longitudinally on a road, comprising the steps of:

• arranging first, second, and third disk-shaped rollers having the same outer diameter so that the rollers have a predetermined spacing therebetween on the same straight line and rotate in the same straight-line direction;
• using a measurement block constituted of a first predetermined-length coupling rod which is mounted on rotary shafts of the first and second rollers to couple the first and second rollers in a revolving manner, a second coupling rod which is mounted on rotary shafts of the second and third rollers to couple the second and third rollers in a revolving manner, distance measurement means which measures a movement distance of the rollers, and angle detection means which detects a displacement angle by which the first and second coupling rods have revolved from a straight state thereof, to elastically attach the measurement block to a measurement vehicle with a coupling member so as to be urged against the road surface;
• deciding a plurality of survey positions obtained as a result of dividing into a plurality of pitches a reference distance which is defined as a center-to-center dimension between the first and third rollers in a condition where the first and second coupling rods are in a straight state;
• each time the leading roller reaches the survey positions sequentially in an advancing direction in which the measurement block moves over the reference distance in a longitudinal direction of the road surface, detecting a displacement angle between the first and second coupling rods at each of the survey positions using the angle detection means;
• calculating height data of the road surface at each of the survey positions using a filter operation method based on the detected displacement angle value obtained by the angle detection means and known height data at each of the immediately preceding survey positions measured by the measurement block, to obtain a unit road surface profile over the reference distance;
• and
• integrating the consecutive unit road surface profiles in the entire longitudinal direction of the road surface, to create a longitudinal profile of the road surface.