FCC Construcción

The project was to build a rail tunnel to serve as both the connection between Atocha Station and Chamartín Station (both of which are in Madrid) and as a through station for AVE high-speed trains. This tunnel enables lines starting or ending in southern and eastern Spain to make connections with the lines in the northern half of the country.

The section contains a double set of international-gauge tracks a total of 7.3 kilometres long. Of this length, which runs through some densely packed areas of Madrid, 6.9 kilometres travel underground in order to cause minimum upset. They cross above Line 9 of the Madrid Metro, beneath another eight Metro lines and beneath the Spanish-gauge Atocha-Recoletos-Chamartín and Atocha-Sol-Chamartín tunnels (which provide service for local and long-distance domestic trains), at an average depth of 45 metres.

Most of the tunnel was dug by a TBM, except for a 110-metre-long section next to Chamartín Station, which was excavated as a trench with retaining pile walls and later covered, and a 22-metre-long section using the top-down cut-and-cover or lid method, next to Atocha Station.

The tunnel was lined with 1.8-by-0.36-metre lining segments assembled by the TBM itself, and it has eight emergency exits.

As an extension of the new high-speed tunnel, another tunnel is being built that will act as a bypass around the recently inaugurated Atocha Through Station.

This rail connection between the stations of Atocha and Chamartín will be essential for the development of a good international-gauge railway system in Spain.