Düker: Tunnel underneath the river Rhine

770 meters long, 2.6 meters in diameter, 256 concrete pipes: These are just some of the figures from Düker 3 (culvert no. 3), which runs from the central power plant and under the Rhine before ending at the Friesenheimer Insel. So, what is it like to walk through the culvert yourself? We joined Bernd Nitschke from the Pipe Racks, Product and Utility Piping unit (ESI/EF) on his inspection underneath the Rhine. 

Once a month, Bernd Nitschke makes his way to K111. The entrance to culvert no. 3 is located directly on the bank of the Rhine. Before the inspection tour begins, all “first timers” have to take part in a safety induction. Nitschke then checks the current oxygen level and the temperature in the culvert tunnel using a monitoring device. The levels are fine and the tour can begin. 

Take a walk underneath the Rhine in BASF`s Düker! (German)

We enter the culvert through the building located above, K111. A metal walkway is attached to the ground and we start with a steep descent. Despite the wintry temperatures above ground, the temperature in the culvert is a warm 30°C. It is a lot less comfortable here during the summer months, explains Nitschke, as despite the insulated piping, the air temperature can reach 40°C. One of the pipes is a 40-bar steam pipe. Since July 2006, this pipe has been used to provide the Friesenheimer Insel site with steam drawn from the central steam network at the Ludwigshafen site. Every hour, between 80 and 90 metric tons of steam flow through the pipe. The employees at the power station ensure that the pressure and the quantity correspond to the requirements at the Friesenheimer Insel site.

And we follow this exact pipe further and further below the Rhine. After around 15 minutes of walking, Nitschke suddenly stops. “Do you all have your passports with you?” he jokingly asks, and goes on to explain that we are currently at the deepest point of the tunnel, located directly below the middle of the Rhine. He points at a sign and adds that we are also about to cross the state border between Baden-Württemberg and Rhineland-Palatinate. Above us are approximately 10 meters of sand and gravel, and above that, another 3 to 4 meters of water, depending on the Rhine’s water level.


metres long is the conrete tube which connects two plants and, what is more, two federal states underneath the water.  

Friesenheimer Insel were pushed through the sand and gravel under the surface of the water, all the way to the Ludwigshafen site.

The drill took three months to dig the 770-meter-long concrete tunnel under the Rhine to Ludwigshafen. We are told that every three years, the thickness of the layer of sand and gravel covering the culvert is measured, and if the thickness is insufficient, sand and gravel have to be added again. 

The route gets tougher after we cross the border, as the temperature remains high, and we also begin our ascent. By now, only soil is above us, as only about one-third of the culvert is actually covered by water. The inspection has already been going on for 45 minutes before we reach the end of the long tunnel and with it, the building above it on the Mannheim side of the Rhine. Bernd Nitschke leads us up 40 stairs into building FA315 and out into the daylight. Looking around from here, it is hard to imagine that we were deep beneath the Rhine just a few minutes ago.