The link between the lightrail stations "El Humedal" and "Universidad de Oviedo" is missing in Gijon, northern Spain, hence, a new connection had to be built. The tunnel route was planned with a length of 3.5 kilometers, crossing under two rivers and built-up areas. Both geology and route looked challenging, but manageable.
Work with the EPB shield S-255 began in April 2004. However, en route for the University, progress came to a sudden halt, as unsuspected geological obstacles caused a change of direction. For nearly a year no further progress was made but with an extra 500 meters of tunnel the project finished successfully after two and a half years in December 2006. It may have meant a detour for the machine but for the students it is a short cut.