For the re-profiling of roads, the existing road profile is usually determined by survey. Re-profiling is meant to improve the uneven profile of a road by milling and asphalting. The current survey instruments,such as tacheometry and levelling, are actually a nuisance to traffic and are unsafe. The policy of the Ministry of Transport, Public Works and Water Management is to keep this problem to a minimum. The Road and Hydraulic Engineering Division (DWW) has, therefore, examined whether the re-profiling measurements can be done from a moving vehicle. A feasibility study was carried out by the National Aerospace Laboratory (NLR) in 1993 at the orders of the DWW. This study indicated that it is necessary to use an Inertial Navigation System (INS). INS is a gyro system consisting of a combination of gyro's and accelerometers. By combining the measurements from the INS-system with the ultrasonic sensors of the Ionic sensors of the ARAN measurement vehicle belonging to DWW, the longitudinal and transverse profile of the road can be measured simultaneously at relatively high speeds (maximum 90 km/h). The INS was tested in experimental deployment in 1994. The test was carried out on a road section of which the exact profile had been determined by means of rod and level survey. From the analysis of the measurements in the test, it appears that with the new gyro system a longitudinal profile can be obtained that agrees, within a centimetre, with profile obtained by survey methods. (standard deviation=0.5 cm, maximum deviation 1.2 cm). The transverse profile can also be measured with this accuracy. (A)
Abstract