Bavaria commissions HELLER with pilot project

First network-wide survey of the load-bearing capacity of Bavarian state roads

The Free State of Bavaria is the first German state to use the so-called Traffic Speed Deflectometer (TSD) for the network-wide recording of the load-bearing capacity of a total of 14,500 km of state roads. The method developed in Denmark measures the short-term deformation of the road under a vehicle axis using laser sensors. First results are expected in spring next year.

The maintenance of road infrastructure can only be sustainable and economical if reliable information on the road structure is available. The condition survey and assessment, which is carried out every four years, provides important data on the quality of the road surface. In order to gain insights into the underlying pavement layers, the load-bearing capacity of the road must be investigated.

So far, the so-called Falling Weight Deflectometer (FWD) has been used for this purpose, in which a weight is dropped onto the road and the temporary hollow is measured using geophones. However, this method is only suitable for recording specific sections of a road. The Traffic Speed Deflectometer (TSD) developed by the Danish company Greenwood, on the other hand, measures the short-term deformation of the road due to vehicle load while driving. Since the measuring vehicle fits into normal traffic at speeds of up to 80 km/h, entire road networks can be surveyed without traffic obstructions. The measuring vehicle used in Bavaria is also equipped with a georadar device to assess the thickness of the pavement layers. The road surface is exposed to electromagnetic rays to measure the reflection time.

The measurement is carried out by the Polish research institute Instytut Badawczy Dróg i Mostów (IBDiM). HELLER Ingenieurgesellschaft mbH is responsible for the quality assurance, evaluation and visualization of the data. The Bavarian State Ministry for Housing, Construction and Transport is responsible for financing and technical support. The Federal Highway Research Institute supports the project technically as well.