The worlds’s largest platform cavern
A major feat of civil engineering, with the largest earth-excavated platform cavern in the world
The new "Puerta del Sol" station, located on the plaza of the same name, built by FCC for the Ministry of Development's Railway Infrastructure Administration, comprises part of the second commuter train tunnel between Atocha and Chamartin, totaling 8,500 meters in length, which has been operating since July 9, 2008.
Its construction, unique due to its engineering features and location, posed a major technical challenge placing Spanish engineering in the forefront worldwide.
The station, comprised of two main parts - the platform cavern and the station entrance and metro connection lobby.
The platform cavern is the largest in the world to have been excavated in the ground to date. The cavern measures 207 meters in length x 20 m. in width x 15 meters in height.
It was designed as a two-level space: the lower platform area and the upper level, referred to as the mezzanine, which facilitates passenger traffic throughout the building for accessing the platforms and the station lobby. It is located below the east block of Montera Street and was built using the German method, which is an orderly process of excavating and concreting successive galleries excavated by conventional mining methods. In the construction process, the framing section of the cavern is built first to afterward proceed to the interior excavation.
For this purpose, in an initial phase, which was begun in November 2004, two pits were dug, from which the cavern was then built. These pits, seven meters in diameter, were excavated by sections up to their baseline level, which, in the Montera Street pits, was located at a depth of 40 meters, equivalent to a 13-story building.
Afterward, from the pits, the soil pretreatments were then completed by means of consolidating injections, gap filling, compensation, reinforcement and improvement, all of which was to assure the full protection of the buildings and structures located above the cavern. These measures have ensures the stability of an area measuring 1.5 hectares. The drillholes drilled for injections totaled a length of over 15 kilometers in all.
The entire cavern construction process was carried out by means of 400 checkpoints located above ground and in the nearby buildings, the data of which was taken and analyzed several times a day.
The station lobby
The station lobby for accessing and transferring to the metro system is located on the east part of the plaza, where the bus stops were formerly located.
The station lobby was built from ground level using barriers, measures 7,500 m2 in area, divided among six levels, being 28 meters in depth, equivalent to the height of a nine-story building.
Before starting building, the necessary space for its construction had to be accommodated. For this purpose, a preliminary phase of detecting and locating up to 228 utilities pertaining to 30 entities, many of which were not on record anywhere, was carried out. Next, the same were then re-routed, rearranged and improved. The complexity of the utility re-routing process made it necessary to build two new gallery, equivalent in height to a two-story building. Two large-diameter water supply pipes were located in one of these galleries, all of the other rearranged utilities having been located in the other gallery. It was also necessary to house a new electric power transformer station inside this station.
This major engineering feat received careful architectural treatment. The lobby access is outfitted with escalators, which made it necessary, for their protection, to build a pavilion, designed by Antonio Fernández Alba, an architect of renowned prestige and a member of the San Fernando Royal Academy of Fine Arts. The uniqueness and meticulous design of this steel and glass structure will now become part of the image of the "Puerta del Sol", one of Madrid's most emblematic spots.
On the interior, the spaces have been adapted to the different requirements set out, one of the most noteworthy of which is a new police station and the museum housing the ruins of the "Iglesia del Buen Suceso" church, found on starting construction on the lobby. Also, as is customary in railway stations, the Sol station has a clock, the face of which is a copy of the famous clock of the "Puerta del Sol".
The commuter train station is outfitted with 16 escalators in the platform cavern and 14 in the transfer point. This station is also equipped with advanced security, communications and accessibility systems, one of the most noteworthy of which are a total of eight elevators; three ventilation shafts; emergency exit, fire detection and extinguishing systems, CCTV and cell phone, among other facilities.
Special attention has been given to making this station handicapped accessible. Measures have been incorporated including: guide strip integrated into the pavement; braille indications on handrails and elevators; double railings on handrails; warning pavement on platform edge, as well as a fluorescent cord marking the train stopping point on the platform.
The Sol station will be the new transfer point between the commuter system and the metro system, providing for easy transfer among the C-3 and C-4 commuter lines and metro Lines 1, 2 and 3. Over 70,000 travelers are anticipated to be using this new station daily in 2010.