Princess Margriet Tunnel Aqueduct

The Princess Margriet Tunnel near Uitwellingerga, close to Sneek, is an aqueduct that also functions as a traffic tunnel and runs under the Princess Margriet Canal. It is part of the A7 motorway and connects the Sneekermeer with the Aldhôf via the Modderige Geau and the Sânepoel. 

The aqueduct is accessible 24 hours a day to road traffic, slow traffic and shipping.

The tunnel was constructed using the usual sinking method, but in a unique way: the tunnel elements were made on site because they were too large to be transported from elsewhere.

In 2022, rising groundwater pushed up part of the tunnel, forcing the A7 to be closed for more than a month and a half. The tunnel was temporarily stabilised with almost 10,000 sandbags and concrete blocks. The problem was partly caused by a design flaw: too little steel had been used, causing rust and weakening the foundation. Around 1,100 tension poles and 250 wall anchors were installed for the repair.