In the Scottish city of Glasgow it rains on average over 200 days a year, with total precipitation of about 1,100 mm. Berlin averages only 115 rainy days and Seville in Spain just 65. In order to prevent flooding and improve water quality in the region, the Glasgow sewage system is constantly being expanded, for example with the Shieldhall Tunnel, Scotland's largest wastewater tunnel.
For the almost 5 kilometer long sewer pipe, a Herrenknecht Mixshield spent 15 months excavating a tunnel in the south of the city from Craigton to Queen’s Park. Tunnelling began in July 2016. More than 3,200 segments were installed to line the tunnel before the tunnel boring machine with a diameter of almost 5.5 meters completed its mission in October 2017. During the advance with minimum overburdens of only 4 meters, sensitive track sections and former coal mines were successfully passed.
The new Shieldhall Tunnel provides an additional 90,000 m³ of storm water and wastewater capacity. Over 500,000 tonnes of material were removed for the modern infrastructure.