Roughness is a fundamental requirement when it comes to galvanizing sheet metal for making cars. Segal worked with Alstom and DMO to develop a measuring apparatus that makes it possible to monitor the Ra roughness factor at every point and throughout the process. The new system has been installed on the Segal galvanizing line. Two measuring heads (WINDIS) with travelling system have been installed, one on each side, after the skin-pass allowing a continuous measurement of the roughness. Alstom roughness control system is composed of an Alstom HPC controller linked to Windis and PC computer. The roughness measurement system has been in operation for a few months and the results show a very satisfactory correlation of Windis measurements with the manual measurements carried out in the laboratory.