Description
The load-bearing capacity of traffic superstructures is usually assessed based on deformation measurements. The bearing capacity is defined as the superstructure's resistance to short-term deformations. However, different measurement concepts and evaluation methods are required for different superstructures to assess the bearing capacity. Therefore, different methods for road and tramway superstructures will be presented in this paper and exemplified by practical examples.
The bearing capacity of road pavements is typically assessed by deflection measurements using the falling weight deflectometer (FWD). In this dynamic measurement method, a falling weight is applied to the road surface, and the resulting deformation basin is recorded for a short time. This can then be evaluated. Non-destructive measurements can be carried out with the FWD, so comparative repeat measurements at individual points are also possible later. Evaluations of various measurements in Germany are presented.
The assessment of load-bearing capacity in the tramway sector is not currently established in German regulations. An individual measurement concept was developed and applied to assess the load-bearing capacity in urban transportation. In addition to vertical deflection, lateral displacements, as well as torsion of the grooved rail and torsion at the rail head, are to be considered. The measurements aimed to determine the in-situ deformations of the grooved rail with a selected type of fastening during the passing of tramways. In addition, the serviceability during operation was checked. The measurements were carried out on an open construction (grass track) and a closed construction (asphalt). Furthermore, track sections with tight curves and straight track were investigated. The applied measurement concept was developed for application in a large German city and can detect the above-mentioned movements. Based on the deformations determined, conclusions can also be drawn about the service life.
