The Pajares Base Tunnel is a twin pair of railwaytunnels beneath the Puerto de Pajares pass in the Cantabrian Mountains, Spain. Once completed, the 24,667 m (80,928 ft) length tunnel will form a key portion of the high-speed rail line between León and Gijón, and shall be used by both high speed passenger trains as well as by slower freight trains.
Works on portal
Work commenced on the Pajares Base Tunnel following its authorisation in 2003. During the construction process, multiple setbacks were incurred on the part of the geological conditions present, particularly the copious ingress of water into the tunnels. Despite multiple years of remedial work and the deployment of unique engineering solutions, the infiltration issue has proved to be difficult to address, and questions have arisen as to if its electrification is even practical. As a result, the fitting-out of the tunnel has been delayed by several years. Early on, the through route was expected to be open in 2010. As of January 2023, the tunnels are expected to be open to passenger traffic in 2024.[1]
ConstructionEdit
During the early decades of the 21st century, Spain allocated a large proportion of European Union-supplied infrastructure funding into the expansion of its AVE high speed rail network.[2] On 1 March 2002, it was announced that Gestor de Infraestructuras Ferroviarias (GIF) had awarded a €5·18m contract to Ineco and Geoconsult for the design of a new 50 km high speed railway between La Robla and Pola de Lena, forming a part of the main line between Madrid - Oviedo main line. The most prominent civil engineering work of this line is the twin-bore Pajares Base Tunnel, which necessitated a length of 24,667 m (80,928 ft) to traverse the Pajares pass of the Cantabrian Mountains.[3] It was reportedly regarded as being one of the largest and most challenging civil engineering projects anywhere in Europe at that time.[2] The tunnel would replace a relatively steep and winding conventional route through the mountains that had limited train speeds to a maximum speed of 70 kmph, while the new line was envisioned to facilitate speeds of up to 300 kmph.[4]
During 2003, the Public Works Ministry awarded a €1.8 billion contract for the Pajares Base Tunnel's construction to a consortium involving the majority of Spain’s major civil engineering firms, including FCC, Acciona, Dragados, Ferrovial, Sacyr, and Constructora Hispánica.[2] As originally planned, both bores of the Pajares Base Tunnel would have been furnished only with standard gaugehigh-speed rail; however, mid-way through construction, it was decided that a dual gauge arrangement would be installed instead, as it was thought that the presence of Iberian gauge would make the tunnel particularly useful to freight trains as well.[5] It had been anticipated that the completed tunnel would facilitate a journey time of 2 hours and 12 minutes between Madrid and Oviedo by 2010.[6]
Its execution began with five TBMs (four for the large tubes and the fifth for the gallery from Buiza) between July and September 2005 on the León slope and between April and July 2006 on the Asturian slope. The tunnel boring machines extracted 4.3 million m³ from the tunnels. The bulk of the excavation work for the Pajares Base Tunnel was performed by tunnel boring machines (TBMs).[6][7] The construction soon encountered substantial amounts of underground water, the presence of relatively porous karst in the vicinity of the bores had been previously identified by surveys undertaken in the 1980s; accordingly, vast quantities of water continuously infiltrated into the bores. It has been alleged by construction workers that management had prioritised maintaining a high rate of progress over properly sealing the tunnel against water infiltration.[2] Furthermore, the geological conditions surrounding the tunnel featured multiple areas of high compressive tectonic stress regimes, such as thrust faults, which necessitated greater levels of support to be installed in the tunnel than had been originally anticipated.[8][9] Despite this, the boring process was completed eight months ahead of schedule. On 11 July 2009, a ceremony was held to mark the completion of the tunnels.[2]
However, despite this milestone being attained, the fitting-out of the tunnel proceeded at a very slow rate due to the water infiltration issue; up to 2,200 liters of water was reportedly entering the tunnel every second, much of it via cracks in its concrete walls.[4] Conventional waterproofing measures, such as polymeric paste injection and polymeric membranes, proved insufficient, while additional excavation was prohibitively expensive due to the walls being largely complete already. Instead, engineers turned to unorthodox means of channeling the water by installing a first-of-its-kind composite lining.[4] After four years of work, the rate of water infiltration had been reduced by 40 percent.[6] By 2014, the difficulties of constructing the Pajares Base Tunnel had become thoroughly apparent.[2] Over the course of one decade, the initial plans of the tunnel were altered on 15 occasions. The costs of its construction has overrun substantially, rising to €3 billion against the originally budgeted price of €1.8 billion.[2]
During June 2020, it was announced that Administrador de Infraestructuras Ferroviarias (ADIF) had awarded a €53m contract to a consortium of Alstom, Indra and the San José Construction Group to supply tunnel safety and security systems for the 12 tunnels of the Pajares New Line project, including the Pajares Base Tunnel.[10] Despite plans for the tunnel to be electrified by 25 kV AC throughout its 24,667 m (80,928 ft) length, questions have been raised if electrification is feasible due to the high level of water infiltration present.[6]
ReferencesEdit
^"Adif pondrá a disposición la infraestructura de Pajares en la segunda quincena de febrero para iniciar después las pruebas de fiabilidad". Adif (in Spanish). 19 January 2023. Retrieved 19 February 2023.
^ abcdefgMendez, Rafael (7 May 2014). "€1.2 billion over budget and still no opening date in sight". english.elpais.com.
^"Pajares base tunnel contract". railwaygazette.com. 1 March 2002.
^ abcMason, Karen (7 January 2018). "Composites perform water rescue in high-speed rail tunnel". compositesworld.com.
^"Fomento prevé concluir las obras de la variante Pajares a finales de 2020". La Vanguardia (in Spanish). 15 June 2017. Retrieved 5 March 2020.
^ abcdBent, Mike (Autumn 2014). "Pajares: A Wet, Warm Tunnel, and other White Elephants" (PDF). eurorail.org.uk.
^Pyeon, Jae-Ho (March 2016). "Trend Analysis of Long Tunnels Worldwide" (PDF). Mineta Transportation Institute.
^Hijazo, T. and Vallejo, L.I. (2012). "In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain". Engineering Geology. s 137–138: 13–20. doi:10.1016/j.enggeo.2012.03.007.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Pablo Valenzuela, María José Domínguez-Cuesta, Mónica Meléndez-Asensio, Montserrat Jiménez-Sánchez, José Antonio Sáenz de Santa Marí (2015). "Active sinkholes: A geomorphological impact of the Pajares Tunnels (Cantabrian Range, NW Spain)". Engineering Geology. 196: 158–170. doi:10.1016/j.enggeo.2015.07.007. ISSN 0013-7952.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Cuenca, Oliver (20 July 2020). "Adif awards €53m systems contract for Pajares New Line project". railjournal.com.
pajares, base, tunnel, twin, pair, railway, tunnels, beneath, puerto, pajares, pass, cantabrian, mountains, spain, once, completed, length, tunnel, will, form, portion, high, speed, rail, line, between, león, gijón, shall, used, both, high, speed, passenger, t. The Pajares Base Tunnel is a twin pair of railway tunnels beneath the Puerto de Pajares pass in the Cantabrian Mountains Spain Once completed the 24 667 m 80 928 ft length tunnel will form a key portion of the high speed rail line between Leon and Gijon and shall be used by both high speed passenger trains as well as by slower freight trains Works on portalWork commenced on the Pajares Base Tunnel following its authorisation in 2003 During the construction process multiple setbacks were incurred on the part of the geological conditions present particularly the copious ingress of water into the tunnels Despite multiple years of remedial work and the deployment of unique engineering solutions the infiltration issue has proved to be difficult to address and questions have arisen as to if its electrification is even practical As a result the fitting out of the tunnel has been delayed by several years Early on the through route was expected to be open in 2010 As of January 2023 the tunnels are expected to be open to passenger traffic in 2024 1 Construction EditDuring the early decades of the 21st century Spain allocated a large proportion of European Union supplied infrastructure funding into the expansion of its AVE high speed rail network 2 On 1 March 2002 it was announced that Gestor de Infraestructuras Ferroviarias GIF had awarded a 5 18m contract to Ineco and Geoconsult for the design of a new 50 km high speed railway between La Robla and Pola de Lena forming a part of the main line between Madrid Oviedo main line The most prominent civil engineering work of this line is the twin bore Pajares Base Tunnel which necessitated a length of 24 667 m 80 928 ft to traverse the Pajares pass of the Cantabrian Mountains 3 It was reportedly regarded as being one of the largest and most challenging civil engineering projects anywhere in Europe at that time 2 The tunnel would replace a relatively steep and winding conventional route through the mountains that had limited train speeds to a maximum speed of 70 kmph while the new line was envisioned to facilitate speeds of up to 300 kmph 4 During 2003 the Public Works Ministry awarded a 1 8 billion contract for the Pajares Base Tunnel s construction to a consortium involving the majority of Spain s major civil engineering firms including FCC Acciona Dragados Ferrovial Sacyr and Constructora Hispanica 2 As originally planned both bores of the Pajares Base Tunnel would have been furnished only with standard gauge high speed rail however mid way through construction it was decided that a dual gauge arrangement would be installed instead as it was thought that the presence of Iberian gauge would make the tunnel particularly useful to freight trains as well 5 It had been anticipated that the completed tunnel would facilitate a journey time of 2 hours and 12 minutes between Madrid and Oviedo by 2010 6 Its execution began with five TBMs four for the large tubes and the fifth for the gallery from Buiza between July and September 2005 on the Leon slope and between April and July 2006 on the Asturian slope The tunnel boring machines extracted 4 3 million m from the tunnels The bulk of the excavation work for the Pajares Base Tunnel was performed by tunnel boring machines TBMs 6 7 The construction soon encountered substantial amounts of underground water the presence of relatively porous karst in the vicinity of the bores had been previously identified by surveys undertaken in the 1980s accordingly vast quantities of water continuously infiltrated into the bores It has been alleged by construction workers that management had prioritised maintaining a high rate of progress over properly sealing the tunnel against water infiltration 2 Furthermore the geological conditions surrounding the tunnel featured multiple areas of high compressive tectonic stress regimes such as thrust faults which necessitated greater levels of support to be installed in the tunnel than had been originally anticipated 8 9 Despite this the boring process was completed eight months ahead of schedule On 11 July 2009 a ceremony was held to mark the completion of the tunnels 2 However despite this milestone being attained the fitting out of the tunnel proceeded at a very slow rate due to the water infiltration issue up to 2 200 liters of water was reportedly entering the tunnel every second much of it via cracks in its concrete walls 4 Conventional waterproofing measures such as polymeric paste injection and polymeric membranes proved insufficient while additional excavation was prohibitively expensive due to the walls being largely complete already Instead engineers turned to unorthodox means of channeling the water by installing a first of its kind composite lining 4 After four years of work the rate of water infiltration had been reduced by 40 percent 6 By 2014 the difficulties of constructing the Pajares Base Tunnel had become thoroughly apparent 2 Over the course of one decade the initial plans of the tunnel were altered on 15 occasions The costs of its construction has overrun substantially rising to 3 billion against the originally budgeted price of 1 8 billion 2 During June 2020 it was announced that Administrador de Infraestructuras Ferroviarias ADIF had awarded a 53m contract to a consortium of Alstom Indra and the San Jose Construction Group to supply tunnel safety and security systems for the 12 tunnels of the Pajares New Line project including the Pajares Base Tunnel 10 Despite plans for the tunnel to be electrified by 25 kV AC throughout its 24 667 m 80 928 ft length questions have been raised if electrification is feasible due to the high level of water infiltration present 6 References Edit Adif pondra a disposicion la infraestructura de Pajares en la segunda quincena de febrero para iniciar despues las pruebas de fiabilidad Adif in Spanish 19 January 2023 Retrieved 19 February 2023 a b c d e f g Mendez Rafael 7 May 2014 1 2 billion over budget and still no opening date in sight english elpais com Pajares base tunnel contract railwaygazette com 1 March 2002 a b c Mason Karen 7 January 2018 Composites perform water rescue in high speed rail tunnel compositesworld com Fomento preve concluir las obras de la variante Pajares a finales de 2020 La Vanguardia in Spanish 15 June 2017 Retrieved 5 March 2020 a b c d Bent Mike Autumn 2014 Pajares A Wet Warm Tunnel and other White Elephants PDF eurorail org uk Pyeon Jae Ho March 2016 Trend Analysis of Long Tunnels Worldwide PDF Mineta Transportation Institute Hijazo T and Vallejo L I 2012 In situ stress amplification due to geological factors in tunnels The case of Pajares tunnels Spain Engineering Geology s 137 138 13 20 doi 10 1016 j enggeo 2012 03 007 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link Pablo Valenzuela Maria Jose Dominguez Cuesta Monica Melendez Asensio Montserrat Jimenez Sanchez Jose Antonio Saenz de Santa Mari 2015 Active sinkholes A geomorphological impact of the Pajares Tunnels Cantabrian Range NW Spain Engineering Geology 196 158 170 doi 10 1016 j enggeo 2015 07 007 ISSN 0013 7952 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link Cuenca Oliver 20 July 2020 Adif awards 53m systems contract for Pajares New Line project railjournal com External links EditDescription in Spanish Basic facts in Spanish 43 01 10 N 5 46 31 W 43 01944 N 5 77528 W 43 01944 5 77528 Retrieved from https en wikipedia org w index php title Pajares Base Tunnel amp oldid 1175469836, wikipedia, wiki, book, books, library,
