The Weser Tunnel is a vital east-west/ west-east axis for the economic development of the lower Weser region. The tunnel connects the Weser-Ems region with the Weser-Elbe region and strengthens the competitiveness of the Lower Saxony ports inclusive of Bremen. Two tubes each with two lanes without hard shoulders connect the two banks of the Weser south of Bremerhaven and Nordenham at the localities of Dedesdorf and Kleinensiel.

The constructional engineers used shield tunnelling technology in completing the 3,200-meter-long tunnel. A Mixshield of a 11,670-mm diameter bored its way through the ground in the spring of 1999. The innovation on the machine: the isolated invert segment that counteracts clogging and, therefore, a slowing down of tunnelling. On average, the 1,500-tonne tunnel boring machine advanced up to ten meters a day. Breakthrough was achieved at the first tube in a west-east direction in November 2000. The project was completed in November 2001 when the breakthrough was achieved at the second tube. The Weser Tunnel went into service in 2004.