Federal Highway Research Institute

Reference section for measuring systems used to survey the substance characteristics (surface) of carriageways

Visible damages on the road surface are called substance characteristics


The damage directly visible on the road surface gives an initial indication of the damage to the road. Such surface damage is described as substance characteristics (surface), and is regularly surveyed in the course of road monitoring and assessment (ZEB).

The fast moving measuring systems used for this purpose are fitted with area scan or line scan cameras trained on the road surface, and which can be used to record surface damage. During the survey process, it is important to ensure that cracks with a width starting from just one millimetre can be reliably identified. In addition to cracks, other characteristics relevant to the evaluation include patched areas and, in the case of concrete construction, broken corners and damaged edges. As a plausibility check, recourse can be made to images taken by a front camera.

Currently, the measuring systems deployed are principally checked by means of comparison surveys using reference measuring systems on real road surfaces. It has not yet been possible to conduct a test on defined, constant surface characteristics.


To check the measuring systems, a reference section has been built using an asphalt and concrete construction in the southern part of the duraBASt. The section contains all the substance characteristics (surface) to be surveyed under the ZEB. Artificial cracks with different crack widths have been made by using cold plastic to produce an impression of real cracks. Features such as broken corners and damaged edges have been specifically incorporated into the section. Furthermore, test panels with a test sample specially developed for the measuring systems approval process are arranged along the section. Because parts of the reference section lie in the area of an underpass, the influence of alternating light and shade can be simulated during the measurement, and the illumination of the surface images tested.


The picture shows a crack disc A crack disc made of cold plastic, containing an artificial crack created using an impression of a real crack

The utilisation of artificial and unchangeable surface damage together with the deployment of test samples offer an objective and improved process for checking the measuring systems for surveying substance characteristics (surface) under defined peripheral conditions.

In addition to this, the section can be used to test and further develop laser-supported and optical measuring systems, and as a research and development tool for automated procedures to detect substance characteristics.