Four Liebherr crawlers are installing 120m long, 48m deep slurry walls in the centre of Amsterdam for the North-South underground rail line. Because the walls have to be close to historic buildings, vibrations have to be avoided and lasers monitor for the slightest movement in the buildings. The HS 853 HD and HS 855 HD cranes operate with mechanical as well as hydraulic slurry wall grabs. The cranes are owned by the specialist contractors Franki Geotechnics of Belgium and the UK’s Cementation Foundations Skanska.