St. Petersburg Metro, Line 1, Russia

Line 1 of the St. Petersburg Metro is one from the main transport arteries public from the city, known also as “The red Line". Inaugurated in the 1955, is one from the more ancient line of the metropolitan network from the city, connecting different areas key through the center historical and neighborhoods residential. The line has undergone various expansions and improvements in the course of the years, making it an element crucial for mobility urban of St. Petersburg.

The works for Line 1 involved the reopening of two tunnels, each approximately 800 meters long. These galleries cross the bed glacial Neva River at a depth of about 60 meters and collapsed in 1995 due to natural causes. The work consisted of the excavation of two new parallel tunnels, with an internal diameter of 6.40 m for a total length of more than 1,600 m. The excavation was carried out with a 7.40 m diameter full-section hydroshield TBM. The average depth of the route was 55 m below ground, through water saturated sand and clay soils of glacial origin, in the presence of salt water.