Second Maasdelta section sunk at Rotterdam | News
The Maasdelta Tunnel, also known as the Blankenburg Connection, will link Vlaardingen on the right bank with Rozenburg on the left bank of the waterway around 15km west of Rotterdam city itself. It will include a network of road junctions each side connecting to the existing motorway and ring road network, bringing relief to increasing levels of road traffic including freight as the port expands including the two Maasvlaktes, the project was described in detail in MJ May 2023[1].
The tunnel beneath the river comprises two elements sunk into a pre-dredged trench (to maintain sufficient depth for river traffic) and connected to shorter tunnels dug either side on land.
Earlier in 2023 the first section, named Alara, was successfully sunk into position on the south side but problems sinking the second, northern section, named Isabella, caused the operation to be aborted. A cable connection broke and the tunnel was damaged when it contacted the quay on the Vlaardingen side, necessitating the tunnel section to be towed back to Damen Verolme’s nearby drydock for repair.
As well as repairing the tunnel itself, much thought went into ensuring the second attempt would not suffer the same fate. Around six months later the re-scheduled operation got underway in an operation lasting around 36 hours and witnessed by MJ.
Once again, the river was closed to traffic and a flotilla of small craft assembled for the operation. Boluda’s tugs VB Tiger, VB Mars, VB Ebro and Rotterdam towed Isabella the short distance to the location, where it was manoeuvred into position athwart the river.
Four barges were positioned, two above and two below the location, with wire connections to the tunnel. Two further barges, Baak Primair and Baak Secundair, were positioned on top of the tunnel itself to provide services and float free once the tunnel was immersed. This part of the operation included slowly flooding four tanks within the tunnel itself. While precautions had to include counteracting the tidal flow, the tunnel’s minimal air draught allowed a generous Beaufort force seven wind limit for the operation.
The tow-out commenced around 6.30am on the day, arriving at the immersion location around 8am with the actual sinking getting underway mid-afternoon. By the following morning Isabella was in position in the trench and the door to Alara, the southern section of the tunnel, could be opened.
Final works including loosening the lifting points of the tunnel section took longer than planned with the waterway finally opened once again to shipping around 5.30pm on the second day.
The last small section of the tunnel, called the closing joint, is constructed between the northern access ramp and the immersed tunnel section and eventually, sand will be added to the tunnel sides and a one-metre thick layer of stones placed on top of the tunnel for protection.
Tunnel elements of this size – 185m and 205m long – have never been built and sunk in the Netherlands before, at a depth of -30m NAP in a tidal river.
On the surface during the operation there was a sense of quietness and calm, despite the flotilla of around 25 various craft from tugs, multi-cat type workboats and diving vessels to small patrol craft fussing around carrying out their duties.
The whole question of the need for and location of the tunnel has provoked much debate locally and project sponsors Rijkwaterstaat, along with the BAAK consortium (Ballast Nedam and DEME Group), have kept the public abreast with progress including providing public viewing areas and car parking facilities each side of the river with staff on hand to explain what is going on during both tunnel immersion events.
With many of the road connections now appearing to be complete and the tunnel opening planned for 2024, the delay with the second sinking should not affect the schedule. The first stage of the Women’s Tour de France from Rotterdam to La Haye in August 2024 includes two passages through the Maasdelta Tunnel, although a local source said it would only be opened for that event.
References
- ^ the project was described in detail in MJ May 2023 (www.maritimejournal.com)