TRANSPORT | IMMERSED TUBE TUNNELS
Below top : Figure 1. The centrepiece of the A281 link road, near Bremen in Germany, is an almost 1.1km-long immersed tube tunnel to be built along the bed of the Weser river. Credit: Wayss & Freytag
Below bottom: Figure 2. The Weser river immersed tube tunnel will be formed of a total of six long concrete elements, which are being constructed at a dry dock in Bremerhaven. Each will be towed 60km away along the Weser to the construction site on the river. Credit: Eric Shambroom Photography
IMMERSED TUNNEL FOR WESER CROSSING
Motorway expansion is under way in north-west Germany to improve major traffic flows near Bremen, including links for road freight as well as to the port and airport. A key gap is the connection missing between the A1 and A27, now being closed with an immersed tube tunnel in the Weser river. Project briefing by Andreas Böddeker, project director A281 Weser Crossing, Deutsche Einheit Fernstraßenplanungs-und-bau (DEGES), Jens Classen, overall project director A281 Weser Crossing, Wayss & Freytag Ingenieurbau, Roland Herr, freelance journalist
The road crossing beneath the Weser river, which closes the gap in the A281 between the A1 and A27 motorways, is an important project in north-west Germany that will relieve traffic congestion on both and also on the access roads to the Hanseatic city of Bremen. The project was awarded by Deutsche Einheit
Fernstraßenplanungs- und -bau (DEGES), on behalf of Autobahn, to Wayss & Freytag Ingenieurbau. It comprises the construction of the approximately 4.8km-long, four-lane motorway route, including the Weser crossing with an approximately 1.1km-long immersed tube tunnel
(Fig. 1). Parallel construction of two immersed elements in an external dry dock will save around two years of construction time. Work began in mid-2023 and the connection is scheduled to go into operation in 2030.
1 - PROJECT DESCRIPTION AND CHARACTERISTICS One of the last two sections of the A281 motorway still to be built is located between the existing junctions at Seehausen and Gröpelingen, to the south and north of Bremen, respectively. The centrepiece of the new motorway route is the immersed tube tunnel crossing the Weser river. The tunnel will be formed by the longitudinal placement, on-site, of six large concrete elements currently being cast in a dry dock in Bremerhaven. They will be floated in the dock and then towed along the Weser to the construction site around 60km away (Fig. 2). After temporary storage in Bremen‘s industrial port, the elements are to be lowered into an excavated channel across the bed of the Weser. Particular attention is being paid to flood protection
as the excavation pits on both sides of the Weser are affected by the tide. Since the existing flood protection wall on the north side and the dyke on the south side have to be opened for the work, flood protection will be installed on the bulkheads and around the immersion channels. The following services, among others, will be provided:
● Explosive ordnance detection and recovery in the tunnel area and in the Weser
● Construction of excavation pits for troughs, immersed concrete elements, and cut and cover (C&C) tunnel construction in sections on the north and south sides
● Construction of a protective gallery in the area of the slag tip of the Arcelor Mittal Bremen steelworks;
● Trough structures for the north and south sides adjacent to the tunnel structures
● Tunnel sections in the northern and southern areas using C&C
● Construction of the immersed tube tunnel, including dredging work for the trench in the bed of the Weser river
● Construction of the final joint 10 | July 2026
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