Vibroacoustic System for automatic Determination of the Number of Axles of passing Vehicles

In this project, the feasibility of a system for counting axles of passing vehicles by evaluation of carriageway vibrations was investigated for the first time. It was initially planned to use these just for registration of the number of axles by means of overhead bridges in electronic toll systems. Now the application of results in form of an own measuring service and the development of a mobile measuring system is planned as well, which would be able to be demonstrated in form of a pilot system. Contrary to the basic research study, in which measurements were performed exclusively on the same test stretch, the objective of the feasibility study was to enable the counting of axles of passing vehicles using vibro-acoustic methods under realistic conditions on various motorway sections. Special care was taken during the selection of measuring sites and the scheduling of measurements that different carriageway structures, weather conditions and traffic burdens were taken into account in the measurements in order to guarantee highest possible variability of the measured data. The measurements were performed using two different recording systems and sensor types and the data obtained by algorithms of the digital signal processing were compared with each other. Thereby, it could be identified that both sensor types provide near to equal results and moreover, enable clear statements with regard to the number of axles of heavy lorries, so that the chosen path should be continued in any case. Moreover, the absolutely comparable results on asphalt and concrete carriageways indicate the technology’s universal usability.