The development of modern Madrid is closely linked to that of its railway infrastructure. The increase in population forced the city to expand northwards at the beginning of the 20th century, and the construction of new stations, lines and railway connections were planned and implemented at the same time. Today, the capital’s main urban axis runs between the two major stations, Chamartín in the north and Atocha in the south, connected on the surface by the Prado, Recoletos and Castellana promenades and underground by three tunnels: two for commuter trains and one for high-speed trains, which has not yet opened.

Of the three tunnels, Recoletos was the first to be opened, in 1967, at the same time that the city was growing along the new urban corridor. With the opening of the subway, which had two stops –Recoletos and Nuevos Ministerios– development began on what starting the 80s would be Madrid’s commuter rail network, the largest in the country, which today carries more than 900,000 passengers every day.

The Recoletos tunnel is still the busiest in the country today: 470 trains and 200,000 passengers pass through it each work day

Recoletos is still the busiest railway tunnel in the country today: 470 trains and 200,000 passengers pass through it every work day, for a total of almost 3,300 journeys each week. 98% of this traffic corresponds to the Madrid commuter rail lines C-1, C-2, C-7, C-8 and C-10 –the rest runs through the Sol tunnel– along with some twenty medium- and long-distance trains per day.

Although improvement works were carried out in 2008, 2009 and 2012, the intensive use of this infrastructure after more than half a century in service made it necessary to undertake a more thorough renovation of the underground system. On behalf of Adif, Ineco provided the project and management of the works, as well as technical assistance, which required the closure of the tunnel between June and November 2019; on 17 November, the 7.3 kilometres tunnel was reopened to traffic.

Recoletos Station. / PHOTO_ELVIRA VILA (INECO)

The works were carried out against the clock in order to minimise the impact on Madrid’s railway network, which began operations in the mid-19th century. The first railway line in the capital, initially for the exclusive use of the Royal Family, linked Madrid with the Royal Palace of Aranjuez and was opened in 1851. It started from a stop (or ‘boarding platform’ as it was known at the time) that would later become the Mediodía station, today’s Atocha station.

The development of the railway parallels the growth of the city, which until the end of the 18th century was enclosed within walls with their corresponding puertas or ‘gates’, with the Puerta de Alcalá and Puerta de Toledo, for example, surviving up to the present day. The last wall, built by King Felipe IV, was demolished in 1868, making it possible to expand the city.

The TUNNEL layout follows the main urban corridor of Madrid, from Atocha to Chamartín, under the great boulevards of the capital

The first urban development plans, at the end of the 1920s, proposed growth along a large new north-south avenue that would structure the city, the Paseo de la Castellana. This planning included, among other installations, a new railway network of which the Recoletos tunnel was a part, which was designed and planned in 1933 following the same alignment of the future Paseo de la Castellana. The outbreak of the Spanish Civil War (1936-1939) and the economic difficulties of the post-war period paralysed these and many other projects for years, including the underground, which finally opened four decades later.

At the beginning of the new millennium, the growth in the demand for transport drove the expansion of the commuter rail network: In 2008, a second tunnel, Atocha-Sol-Nuevos Ministerios-Chamartín, was opened. A third tunnel, also between Atocha and Chamartín, which has already been completed, will be dedicated exclusively to high-speed trains, connecting all of the lines in the network.

ATOCHA (94,5M passengers/year*)

Built on the former Mediodía station, the existing railway complex, the largest in Spain, was opened in 1992 along with the Madrid-Seville high-speed line. It consists of two stations, the commuter station and the high-speed station. It is located in the Glorieta del Emperador Carlos V, where the Paseo del Prado begins and continues north to the Plaza de Colón. The three major national museums are located in this area: the Prado, the Museo Nacional Centro de Arte Reina Sofía and the Thyssen Museum.

Atocha Station. / PHOTO_ELVIRA VILA (INECO)

RECOLETOS (9,3M passengers/year*)

In the 16th and 17th centuries, this was an area with orchards known as Prado de Recoletos, in reference to the convent of Augustinian friars, located on the site now occupied by the National Library and the Archaeological Museum. The Paseo de Recoletos begins at the Plaza de Cibeles – with its famous fountain, a symbol of Madrid, and which houses, among others, the Palacio de Telecomunicaciones and headquarters of the City Council – and ends at Colón. In the 1960s and 1970s many old palaces and buildings were demolished and replaced by modern buildings.

Recoletos Station. / PHOTO_ELVIRA VILA (INECO)

NUEVOS MINISTERIOS (35,1M passengers/year*)

In the 1930s the city’s growth towards the north was first planned, along a large avenue, the Paseo de la Castellana, which opened to traffic in 1952, and Azca, a new residential, commercial and entertainment area. The Nuevos Ministerios complex was built alongside it and the first underground suburban station was opened here in 1967, located under the central courtyard. After several extensions, it has now become a large interchange, connecting to three metro lines and seven suburban lines.

Nuevos Ministerios Station. / PHOTO_ELVIRA VILA (INECO)

CHAMARTÍN (24,2M passengers/year*)

The route of the tunnel is separated from the axis of the Paseo de la Castellana until it reaches this station, which gets its name from the former village of Chamartín de la Rosa on which it is located. The first station was opened in 1967, and eight years later the new railway terminal was designed by the architects Alonso, Corrales and Molezún, along with the engineer Rafael Olaquiaga. In 2008, it was renovated to adapt to high-speed trains and connect to the new Sol tunnel. The next major remodelling has already begun with a view to the commissioning of the third exclusive high-speed tunnel between Atocha and Chamartín.

Chamartín Station. / PHOTO_ELVIRA VILA (INECO)

Track and overhead line renovation: The making-of step by step

1. To renovate the track, first the old ballast was removed (stripped) and collected on a conveyor train. In total, 15 km were cleared. 2. The ballasted track was lifted and replaced by slab track. The picture shows the new bi-block sleepers, type BP-SO, ready for the pouring of the slab track. 3. The concrete was poured directly in order to create the slab. In total, 23,000 m3 of reinforced concrete was used. 4. Machinery for the correct positioning of the track. Throughout the tunnel, 29,400 m of rails were installed in 288-metre long bars. 5. Pouring of track 2 from track 1, already completed, with a three-tank train. 6. Additional work carried out included the installation of 25 new track devices: 7 turnouts, 8 crossovers and 1 bretelle. In the image, at the entrance of Nuevos Ministerios, one of the turnouts that has already been assembled; in the tunnel vault, supports for the new rigid overhead line. 7. Assembly of part of the 1,300 rigid catenary bars installed in the tunnel. 8. The completed track, with the rigid overhead line already installed. 9. Running of new signals, wiring and signalling elements. 10. Electronic signalling control points were installed in the Recoletos and Nuevos Ministerios stations, upgrading the existing technology to a safer system.

This project, approved by the Ministry of Public Works in March 2015, is very important for Spain’s rail network. When completed, the high-speed lines of the north, south and south east of the Iberian Peninsula will be connected by a 6.8 kilometre-long tunnel (7.7 kilometres including the tunnel bypass). The use of the international track gauge on the line will shorten travel times by 30 minutes by precluding the need for trains to pass through gauge changers. When the future Atocha through-station is built, Madrid’s two high-speed stations will be connected.

The quadrupling of the track will increase the capacity of the railway infrastructure between Puerta de Atocha station and Torrejón de Velasco, where trains are diverted to the east or south of the Iberian Peninsula. The commissioning of these two new sections, in addition to the two existing ones, will alleviate the congestion on the saturated access lines to Atocha and speed up and facilitate greater density of rail traffic, thereby benefiting the Levante and Andalusia high-speed corridors, as well as removing the need for the existing north-south routes (such as A Coruña-Alicante, Alicante-Gijón, Alicante-Santander, etc.) to pass through several gauge changers.

Track diagram of the new HSL Centre between Atocha and Chamartín (temporary and future arrangement).

OUTFITTING THE HS LINE

The work that the company Adif Alta Velocidad is currently completing includes track assembly, electrification and installation of safety and communications equipment, activities on which Ineco is collaborating by providing consulting services and technical assistance work for monitoring and supervision.

In terms of track assembly, the stretch is divided into two sub-sections: Chamartín-Atocha (8.21 kilometres), which consists entirely of slab track except for a small section on ballast in the transition area from double track to single track at the fork leading to the future through-station and provisional tunnel, and Atocha-Torrejón de Velasco (27.65 kilometres), where the track has been installed on ballast. The project also includes work on Chamartín station, where a railway yard with the UIC international gauge has been built at its southern end.

Regarding the connection of the Southern and Levante high-speed lines at Torrejón de Velasco, two parking tracks, each about 200 metres long, had to be adapted to high-speed line parameters.

THE DEEP TUNNEL THAT PASSES UNDER THE CAPITAL

The tunnel between the Madrid-Puerta de Atocha and Madrid-Chamartín stations is an essential infrastructure for the development of an international-gauge network in Spain, as it allows the interconnection of the high-speed lines that pass through Madrid, facilitating the interoperability of high-speed trains.

Atocha-Chamartín tunnel (Madrid). / PHOTO_ELVIRA VILA

According to Adif, the tunnel, whose boring was completed on 11 February 2011, improves the operating model of the two Madrid stations converting them from a terminal configuration to through-stations. Commissioning of the tunnel will also facilitate high-speed train access to the Fuencarral railway workshops (in Chamartín) and Cerro Negro workshops (next to Atocha) for maintenance. Once the Atocha through-station is built, Madrid will have the luxury of having its high-speed stations connected, a situation that is still pending in other major European cities. Operators will be able to choose between Chamartín or Atocha stations for their high-speed train arrivals and departures to and from the capital.

With a length of 6.8 kilometres, the tunnel, whose boring began in 2010, runs under the city’s main arteries and emblematic monuments and buildings such as the Puerta de Alcalá and the Archaeological Museum. Equipped with some of the most modern railway technology available  in terms of safety and protection systems, it boasts a slab track with embedded rail, rigid overhead catenary, nine emergency exits and signalling and communication systems with a high level of safety. From the very start, Ineco participated by providing Adif with project and environmental management, geotechnical consulting, building inspection and acoustic monitoring services. Ineco was later responsible for technical assistance on track assembly, electrification and signalling.

Nine emergency exits

Constructed at a depth of about 40 metres, the tunnel features nine emergency exits, one per kilometre: three along Serrano and the others at Atocha, Calle Espalter, Plaza de la República Argentina and Calle Hiedra, Calle Alberto Alcocer and Calle Concha Espina. In the image, the emergency exit leading to Calle Espalter.

A UNIQUE TECHNICAL BUILDING

The building has fibre-reinforced concrete panels and a tubular steel substructure, instead of the usual concrete walls, making it possible to optimize the installation of the façade insulation.

Chamartín technical building. / PHOTO_ELVIRA VILA

The technical building at Chamartín station on the Madrid-Chamartín-Torrejón de Velasco section has two floors to house equipment for services (power, batteries, telecommunications and signalling) as well as offices, storage areas, access roads and a platform for loading and unloading. The Siemens-Thales Joint Venture constructed the building from a project drafted by Ineco, which also provided site management with technical assistance.

In spite of the industrial nature of this type of technical building, an appearance that fit better with the urban environment was sought and achieved thanks to the choice of prefabricated GRC concrete panels (fibre-reinforced concrete), which required minimal thickness, with stiffness provided by the tubular steel substructure. The space gained was used to install the insulation, which is continuous across the façade, minimising the number of thermal bridges. This prefabricated panel system makes it possible to have many different tones, textures and designs. These details make these walls different from typical concrete infrastructure walls and make them resemble prefabricated architectural finishes used in urban construction.

WATCH THE CALCULATIONS

The commissioning of the section of high-speed line between Madrid-Puerta de Atocha station and Torrejón de Velasco, slated for 2018, required the inspection of 34 new structures with a total length of 3.1 kilometres, a job carried out by Ineco for Adif.

Last summer, Ineco began carrying out load tests and inspections on all of the structures of the section between Atocha and Torrejón de Velasco of the new Levante rail access, which passes through the southern part of Madrid and the towns of Villaverde, Getafe, Pinto and Torrejón de Velasco. In total, the new tracks have 34 structures and more than 2.5 kilometres of viaducts. The work to be carried out on bridges, pergolas and viaducts in this type of contract includes full verification of the condition of the structures, consisting of formulating inventories, preliminary inspections, bridge instrumentation, carrying out load tests, as well as calculating the bridge behaviour during testing, and ending with the main inspection of each structure and completion of A1 (communication of inspections to the register of railway bridge inspections) and A2 (load test report) procedures. All of this is collected and published in the final load-test report. This ensures compliance with the mandatory Instruction on Railway Bridge Technical Inspections (ITPF-05), which regulates both inspections and load tests carried out on newly constructed bridges, as is the case, and even on service bridges.

Its most significant infrastructure –in addition to the Chamartín-Atocha tunnel mentioned above– include the provisional tunnel under Atocha station, 879 metres long and consisting of single track, the Perales cut-and-cover tunnel (390 m), and the viaducts over Calle Comercio and the C-5 commuter rail line (127 m), the Abroñigal viaduct (149 m), the Santa Catalina viaduct (429 m over the M-40, and a total of 649 m), the 1.1 viaduct over the Madrid-Levante HSL, Seville branch (1,079 m) and the pergola over the Madrid-Seville HSL (93 m).

THREE UNIQUE METAL VIADUCTS

Of the 34 new structures, three unique viaducts stand out for their location, design and construction process:

• Comercio street viaduct
  This is a 129.5 metre-long bridge with steel structure and auxiliary elements weighing 1,130,000 kg over Calle Comercio and the C-5 commuter rail line (Móstoles-Humanes). Its highly complex construction is due to the viaduct structure with a variable radius of curvature. The structure consists of two metal lateral lattices on both sides of the railway platform, connected every 3.50 m by metal beams on which the concrete deck rests. It has a total length of 129.5 m, distributed over 4 continuous spans. The viaduct construction was executed in such a way as to minimize the disruption of public roads and rail traffic.
  

  Comercio street viaduct (Madrid).

• Abroñigal viaduct
  The Abroñigal viaduct is located near Atocha station, next to the C-4 commuter rail line. It covers a length of 144.5 metres and is built with three spans on a large metal structure with reinforced box-girder elements and welded joints, forming a thick sail-shaped lattice, with a reinforced concrete deck on floor slabs, joined to metal girders by metal connectors. The track layout is straight but eccentric towards the left-hand side. The bridge can only be accessed through abutment 1 (Atocha side), fitted between the tracks on the left-hand side and the embankment towards Calle Embajadores. The access tracks to Adif’s Entrevías workshop and the road tunnel from Calle Embajadores to the same workshop run beneath it. This was a conditioning factor for both the construction as well as the load test and the inspection.
  

  Abroñigal viaduct (Madrid).

• Torrejón de Velasco: viaduct over the Madrid-Levante HSL
  The section between Torrejón de Velasco and the branch that connects to the Madrid-Andalusia high-speed line runs between the municipalities of Torrejón de Velasco (Madrid) and Yeles (Toledo), and corresponds to the branch that connects the Madrid-Castilla La Mancha-Valencian Community-Region of Murcia and Madrid-Andalusia high-speed lines. The railway track is over 7 kilometres long. This section’s most notable elements include the construction of a 1,079 metre viaduct and a pergola 93 metres long. In the case of the load test, in order to avoid interfering with the lower track, the vertical sag or deformations of the metal deck of span 10 was measured using a laser. In terms of the inspection, it posed the usual difficulties of a viaduct of this size, such as inaccessible metal elements, except for the deck, which has hatches in the bottom sheet in sections 9 and 11, next to the part that joins to the concrete deck.
  

  Madrid-Levante HS viaduct (Torrejón de Velasco).

  Installations on the Chamartín – Atocha – Torrejón de Velasco section

  
  SIGNALLING

  • Enlargement of the electronic interlocking system in Madrid-Chamartín high-speed train station, new electronic interlocking system at the Botanical Garden and modification of the system in Torrejón de Velasco.
  • Equipment installed in the field: audio frequency track circuits, electrohydraulic point machines, wayside LED signals, etc.

  
  TRAIN PROTECTION SYSTEMS (ERTMS AND ASFA)

  • ERTMS L1 train protection system and enlargement of ERTMS Levels 1 and 2, at the southern end of Chamartín HS station and ASFA system as a second operating level.
  • New ERTMS control centre, PCE.
  • Fixed and switchable ASFA and ERTMS balises, implementation of transitions between the corresponding levels in each case (L2, L1, LZB) at the ends of the line.

  
  FIXED TELECOMMUNICATIONS AND PROTECTION AND SAFETY SYSTEMS

  • Fully-redundant fibre optic network on both sides of track and fibre optic supervision system.
  • Automatic telephone system.
  • Interconnection of the section’s networks with the CORE MPLS networks and the Madrid-Valladolid and Madrid-Levante sections.
  • Video surveillance, access control and   anti-intrusion system.
  • Integration of civil protection systems.

  
  AUXILIARY DETECTION SYSTEMS

  • 21 falling object detectors.
  • 1 hot box detector.
  • Auxiliary detecion system telecontrol  for the integration and display of section detectors.

  
  CENTRALISED TRAFFIC CONTROL (CTC)

  • Enlargement of Madrid-Valladolid and Madrid-Seville CTCs and adaptation of Madrid-Levante CTC.

  
  POWER SUPPLY

  • Power supply to the field equipment through a 750 V line from the line suppliers (technical buildings and signalling buildings).
  • Electrical connections for Chamartín-Atocha tunnel, technical buildings and electrical substations in Villaverde and El Hornillo.

  
  BUILDINGS

  • New technical building at the southern end of Chamartín.
  • Technical sites at Canal del Manzanares and Cerro de los Ángeles.

  
  PROTECTION AND SAFETY SYSTEMS