Cheaper aquaduct to replace Skarsterbrêge bridge

The bridge in the A6 motorway crossing the Skarster Rien canal can be replaced with an aqueduct at a much lower cost than previously anticipated. In addition, the majority of the work can be realised within 18 months’ time. These are the conclusions drawn by the engineers of Witteveen+Bos in Heerenveen.

In the spring of 2016, Melanie Schultz-Van Haegen, then Minister of Infrastructure and the Environment, cancelled the planned realisation of an expensive aqueduct because spending cuts were necessary. She had set aside EUR 50 million for this aqueduct. Recent bridge malfunctions once again resulted in major congestion problems on the A6 motorway between Joure and Emmeloord. Witteveen+Bos see the cancellation of the aqueduct as a missed opportunity. ‘The A6 is the main link between the Randstad conurbation and the provinces of Friesland and Groningen. It is already a busy road, and it will just keep getting busier,’ says Rinze Herrema of Witteveen+Bos. ‘The reconstruction of Joure junction is nearing completion, and the southern ring road around the city of Groningen will be completed in a few years’ time as well. The corridor between Amsterdam and Hamburg will at that point be obstacle-free, and this will certainly affect the amount of traffic.’

The bridge across the Skarster Rien canal is opened frequently to allow pleasure boats to pass. During the summer season this results in dozens of A6 closures every day. Herrema: ‘In this day and age this is simply not acceptable. All the main roads in the province of Friesland have aqueducts. Except here and at Kornwerderzand, where there are still failure-prone movable bridges, even though it concerns major access roads into Friesland.’ Incidentally, the existing bridges in the A6 require large-scale maintenance works in the near future. The investment needed for this is estimated at over EUR 10 million.

Witteveen+Bos has designed an aqueduct that can be realised for a mere EUR 40 million. This has become possible thanks to improved insights into the construction techniques and the development of cheaper methods. The design is similar to that of the Langdeel aqueduct in the national road N31. According to Herrema the location of the Skarsterbrêge bridge is ideal for the realisation of an aqueduct: ‘It will not be necessary to buy or demolish any buildings. The aqueduct can be built on “virgin land”. And if it is constructed adjacent to the existing A6, the motorway will hardly have to be closed at all. The only negative consequence is that the Skarster Rien canal will be obstructed for a period of ten months, outside the peak boating season.’

In the past, Witteveen+Bos was involved in the construction of a number of Frisian aqueducts, including the Geeuw aqueduct in Sneek and the aqueducts in the national roads referred to as ‘Haak om Leeuwarden’ and ‘De Centrale As’.