Nowadays several types of Falling Weight quality of roads and airfields by the measurement of the pavement-deflection for the purpose of establishing maintenance requirements. Four problems occur:
1. No calibration of the equipment in regular set-up is possible (only calibration of different components)
2. Different types of FWD-devices result in deviating measurement results
3. Measurement results of different types of FWD's are not exchangeable
4. Deflection bowls measured are also different from those caused by wheel load. In conjunction with the Forum of European National Highway Research Laboratories (FEHRL) and in a later stage with the COST 336 action, international interest was gained for this problem. Nevertheless, no generally accepted solution was found for absolute calibration of a group of FWD's. The proposed (co-operative) research project closely connects to the objectives of Theme I of the SMT Programme. The project will develop and improve the scientific base (finite element analyses of pavement and subbase to establish correlation between FWD-type, wheel load bowl shape, pavement structure geometry and sub-base material characterisation) for written European standards. It should finally result in the development of specifications (including measurement protocols) for the installation of harmonised calibration-stations throughout Europe (and possibly beyond) as well as improved simulation of traffic load by FWD's. Important effect of better measurements will be an improved determination of maintenance-activities needed (higher quality of roads). Every percent performance improvement leads to substantial savings (estimate: 17,5 MECU/year). However reducing user-costs has an even stronger impact as well as indirect effects such as lower frequency of maintenance activity and a lower accident risk. Producers of FWD-equipment already expressed their interest and willingness to participate to an eventual research proposal. Partners intend to closely co-operate and discuss the matter with CEN.