Inverted syphon under the river Rhine in Cologne - a new district heating tunnel to be constructed under the Rhine

Drilling rig "Marion" just before starting the inverted syphon project under the river Rhine in Cologne at the Mülheim bridge. The approx. 100 t drill head looks really imposing. 161 reinforced  concrete jacking pipes will follow the route made by "Marion" underneath the Rhine. Each pipe has an impressive outer diameter of 3.40 m, is 4.00 m long, and weighs 30 t. 

Safe recovery from a 24 m depth after precise entry from the Rhine riverbank at Deutz.