Madrid – Valladolid line

Guadarrama tunnel

Introduction

The Guadarrama tunnel is the largest engineering project executed in Spain, which puts us at the head of infrastructures worldwide: it is the first and only tunnel for high-speed use constructed without intermediate stages, the fourth largest in Europe and the fifth in the world.

The construction process was developed based on criteria of meeting the completion deadline and having the minimum possible environmental impact.

The breaking through of the east tube was carried out on May 5th, 2005 in an inauguration ceremony presided over the Minister of Public Works, Magdalena Alvarez. One month later, work was completed with the breaking through of the west tube. Given that the construction began on September 28, 2002, the total time invested was approximately 32 months.


Advantages of the tunnel

The Guadarrama tunnel is the cornerstone of the future high-speed line that will connect Madrid with the principal cities in the north and northwest of Spain.
When it begins to function, the Madrid-Segovia stretch will be covered in barely 22 minutes. The trip all the way through to Valladolid can be completed in 55 minutes.


General information and technical data

Looking at its longitudinal cross-section, from the Madrid side, the tunnels begin at an altitude of 998 meters and reach a maximum height of 1,200 meters with an average gradient of 1.5%. Afterwards they descend to 1,114 meters at the Segovia exit, with a gradient of 0.9%.

The tunnel’s course runs between the municipalities of Miraflores de la Sierra and Segovia. Its geological profile shows five major sections depending on the character of the principal units traversed by the route. There are granites and gneiss with a high degree of consistency, hardness and abrasiveness.


Chart of the morphologic and geologic profile

To describe it briefly, this is a tunnel with two tubes thirty meters apart at their central axes, 28.4 km long.

The two tubes are connected by emergency galleries
located every 250 meters once the tunnels are in service.


TBMs (Tunnel Boring Machines)

The Guadarrama massif has been declared an especially protected area. This meant that the use of intermediate stages could not be used in the tunnel construction, and four tunnel boring machines (TBMs) were used, two for each of the tubes that make up the tunnel.

These machines were designed specifically for extra hard rock, adapted for the characteristics of the route and the geology of the Sierra de Guadarrama massif.

One figure that gives an idea of the magnitude of the project is that between the four machines 4 million cubic meters of rock were extracted.

These TBMs are a “double shield” type, a kind of mobile tunnel factory. These machines offer high levels of safety, productivity and output.

Each of the TBMs, two working from the south entrance in Madrid and the other two from the north entrance in Segovia, advanced at an average pace of 16 meters per day; close to 1,000 meters were excavated in one month. At the same time as the boring process advanced, the TBMs installed the voissoir rings that make up the internal tunnel lining.


Lining

The diameter of the excavation made by these TBMs is approximately 9.5 meters which is reduced to 8.5 meters once it is covered by the voissoir ring, which is 32 centimeters thick.

The TBM allows the excavation to proceed at the same time as the putting into place of a prefabricated reinforced cement lining, the voissoirs, which serve as terrain supports.

The voissoirs, which form the ring lining the tunnels, are manufactured at the worksite. Each of the four tunneling machines is assured of its supply by its own manufacturing plant. Rocks from the excavation were used in their manufacture.

After this process, the tunnel is ready for the installation of the rest of the railway elements.


Environment

A tunnel is the type of transportation infrastructure whose construction and existence cause the least impact on their natural surroundings. Moreover, in this project the decision was made to extend the tubes approximately 1,000 m so that they would not affect protected areas of high environmental value.

From the beginning the measures necessary for the environmental integration of the project were incorporated, protecting the hydrological system, the fauna and the flora.

Following the Environmental Impact Statement, almost 30% of the material excavated was used for the manufacture of concrete in the voissoir plants. The rest was disposed of in dump sites authorized by the environmental authorities.


Safety systems

Once finalized, the tunnel will have interconnection passages located every 250 m. During the construction process itself these galleries are bored every 1000 meters to guarantee worker safety.

The emergency room will be in the middle of the tunnel, between the two tubes. It will be 500 m long, with room for 1,200 people.

The emergency room will be equipped with its own ventilation system, which guarantees it fresh air for 48 hours in case of fire.

The tunnels will be monitored by a control center that will check the ventilation, gallery and emergency room air supply, energy, light, signaling, communications and fire extinguishing systems.


Information summary

  • Budget awarded: 1,219 M €

General tunnel characteristics

Information:

  • Length: 28,407.70 West; 28,418.66 East
  • Excavation diameter 9.50 m.
  • Interior diameter 8.50 m.
  • Distance between axes 30 m.

Material excavated south end

  • Tunnel 1: 1,054,350 m3
  • Tunnel 2: 940,270 m3

Material excavated north end

  • Tunnel 1: 940,270 m3
  • Tunnel 2: 1,054,350 m3

Material recycled

Manufacture of voissoirs, roadbeds and diverse fillings: 22% of the total

Route

  • Minimum radius 8,400 m.
  • Maximum radius 15,000 m.

Lining

  • Each ring or segment of the tunnel is made up of 7 voissoirs.
  • 160 cm-wide voissoirs.
  • Thickness 0.32 m.
  • Volume 15.2 m3 per ring (9.48 m3/m of tunnel)
  • Steel 90 kg./ m3 of concrete
  • Total number of rings 35,472
  • Total number of voissoirs 248,304
  • Approximate volume of mortar filling 286,550 m3

Tunnel boring machines

  • The cutting heads are formed of 60 steel rollers.
  • 250 m long
  • 9.51 m in diameter
  • 4 million m3 of rock extracted
  • Each TBM advances 16 m/day.