Laser scanning is commonly used in railways for detecting problems related with the clearance profile which are quite common especially in old tunnels. By increasing the resolution of the scanner system it is possible to use the images for identifying problems affecting the structure of the tunnel such as, for example, cracks, empty joints, deformation and water inflows. Moreover, since the used scanner system records not only the position but also the temperature of each measured point, it is possible to combine laser and thermo images which allows recognising the presence of water and or empty cavities behind the lining which may be considered major causes of lining weathering. This paper will show how the application of this technique based on laser scanning images analysis modified the tunnel inspection process, necessary for assessing the tunnel condition.