A spectacular Spanish engineering work
The construction of the Guadarrama tunnel has been one of the largest engineering works carried out in Spain and has contributed to placing our country at the forefront of world infrastructures. It is the first and only high-speed tunnel built without intermediate shafts, the fourth longest high-speed tunnel in Europe and the fifth in the world.
The construction process was developed from the criteria of compliance with the execution period and minimum environmental impact.
The East tube was inaugurated on May 5, 2005, in a ceremony presided over by the Minister of Public Works, Magdalena Álvarez. A month later, works on the West tube were completed. A total of 32 months were invested in the construction of this tunnel since the works began on September 28, 2002.
The Guadarrama tunnel is the cornerstone of the high-speed lines that will connect Madrid with the main cities in the north and northwest of Spain.
Since the tunnel was put into service, the Madrid - Segovia route is covered in just 22 minutes, and the trip to Valladolid can be completed in 55 minutes.
In its longitudinal profile, from the Madrid access, the tunnel starts at an altitude of 998 meters and reach a maximum height of 1,200 meters with an average slope of 1.5%. Then, it descends to 1,114 meters at the Segovia access with a slope of 0.9%.
The tunnel route runs between the municipalities of Miraflores de la Sierra and Segovia. Its geological profile consists of five large sections based on the nature of the main units that the route crosses, with granite and gneiss of great consistency, hardness and abrasiveness.
Morphological and geological profile
From a descriptive point of view, it is a double-tube tunnel, with a 30 m distance between tunnel axes and 28.4 km in length.
Both tubes are connected to each other by emergency galleries located every 250 meters.
The Guadarrama massif has long been declared a specially protected area. Therefore, the use of intermediate shafts for the construction of the tunnel was ruled out, resorting to four tunnel boring machines, two for each of the tubes that make up the tunnel.
These machines were specifically designed for extra-hard rock. Therefore, they are adapted to the characteristics of the route and the geology of the Sierra de Guadarrama massif.
Knowing that more than 4 million cubic meters of rock were extracted by the four TBMs may help get an idea of the magnitude of the work carried out.
For this project, double shield tunnel boring machines were used, a kind of mobile tunnel factory. These machines offer high levels of safety, productivity and performance.
Each of the tunnel boring machines, two working from the south entrance (Madrid) and the other two working from the north entrance (Segovia), boring at an average rate of around 16 meters per day, although they reached close to 1,000 meters bored in a month. In parellel with the drilling process, the tunnel boring machines placed the segment rings that make up the internal lining of the tunnel.
The bore diameter of these TBMs is approximately 9.5 meters and, once covered by the 32-centimeter-thick segment rings, it is reduced to 8.5 meters.
After this process, the tunnel is ready for the rest of the railway elements to be installed.
A tunnel is the kind of transport infrastructure whose construction and existence causes the least impact on the natural environment. In addition, for this project it was decided to extend the tunnel approximately 1,000 m so that it would not affect protected areas with high environmental value.
All necessary measures for the environmental integration of the works and for the protection of the hydrological system, fauna and vegetation were implemented from the very beginning.
As per the Environmental Impact Statement, almost 30% of the excavated material was used for manufacturing concrete, in the segment ring plants. The rest was disposed of in landfills authorized by the environmental authorities.
The Guadarrama tunnel has interconnecting galleries, located every 250 m. However, during the construction process these galleries were drilled every 1,000 meters in order to guarantee the safety of the workers.
The emergency room, 500 m long and with capacity for 1,200 people, is located in the middle of the tunnel, between the two tubes.
The emergency room has its own ventilation system that guarantees fresh air for 48 hours in the event of a fire.
The tunnel is controlled by a control center from which the ventilation, gallery and emergency room aeration, energy, lighting, signaling, communications and fire detection and extinction are supervised.
Awarded budget€1,219 million
- Length: 28,407.70 West 28,418.66 East
- Bore diameter: 9.50m
- Inner diameter: 8.50 m.
- Distance between tunnel axes: 30 m.
South entrance: excavated material
- Tunnel tube 1: 1,054,350 m3
- Tunnel tube 2: 940,270 m3
North entrance: excavated material
- Tunnel tube 1: 940,270 m3
- Tunnel tube 2: 1,054,350 m3
Manufacture of segment rings, track beds and fillings: 22% of the total material.
- Minimum radius: 8,400 m.
- Maximum radius: 15,000 m.
- Each ring of the tunnel is made up of 7 segments.
- 160 cm wide segment rings.
- Thickness: 0.32 m.
- Volume: 15.2 m3 ring (9.48 m3 /tunnel meter)
- Steel: 90 kg/m3 of concrete
- Total number of rings: 35,472
- Total number of segments: 248,304
- Approximate volume filled with mortar: 286,550 m3
Tunnel boring machines
- The cutting heads are made up of 60 steel rollers.
- 250 km long
- Diameter: 9.51 m
- 4 million m3 of rock extracted
- Progress of 16 m/day per TBM.