Horcajada Tunnel Breaks Through on Madrid-Valencia High Speed LineTravel times between Madrid and Valencia are set to more than halve on completion of the high speed rail line in 2010, with trains travelling at speeds of up to 350 km/h. Spain already has high speed links from Madrid to Saragossa, Barcelona and Seville. On completion of the Valencia line, extensions are planned to Alicante and Murcia. Work is well underway in constructing the new line to Valencia with numerous packages awarded along the 300 km route.The Horcajada tunnel is situated between Horcajada de la Torre and Naharros in Cuenca province in Castilla La Mancha. It is 3,957 m long, of which 3,877 metres is mined and the remaining 80 metres is cut-and-cover extremities. It is the second longest tunnek on the Madrid-East coast high speed line. The tunnel broke through on 18th June, 2008 at 1,341 metres from the west tunnel mouth to Horcajada and at 2,536 metres from the east mouth to Naharros. Click es/95. View a video at www.rtvcm.es/mm.php?id=http://video.rtvcm.es//automatico/webavecuenca.wmv Acciona Infraestructuras started work on the tunnel in September 2006 in an initial 26-month contract of a value of EUR80.6 million. Land ownership difficulties soon put the project behind schedule but all is now back on track. The Madrid end of the tunnel is at an altitude of 924 metres and the track will peak at a maximum of 967 metres over 3.2 km. It then drops to 964 metres over the final 0.7 km providing an overall difference of 40 metres inside the tunnel to comply with the specified high speed train gradients. The twin-rail tunnel features a final cross-section of 80 square metres with a 6.26 m radius and 7.89 m height.The tunnel is located in an area with abundant Tertiary materials, such as massive grey gypsum with intercalated red siltstone, clays and red sandstone and grey limestone with marly intercalations. This geology conditioned the tunnelling method that is employed, the new Austrian tunnelling method (NATM), which consists of the driving the tunnel in two phases. First, the upper part of the cross-section, or top heading, is dug (6.96 m). This phase is not finalised. In the second phase, the lower part of the cross-section, or bench, is excavated (4.74 m). As a result of the tunnel length and soft rock terrain comprising principally gypsum and clays, Acciona opted for the more cost effective roadheader techniques. Excavation is taking place with two 120-tonne Wirth T3.20S roadheaders, one at each side of the tunnel. These heavy roadheaders are one of the most efficient and most productive means for excavation of tunnels with conventional methods in soil and rock of medium hardness. In this way, the excavated cross-section perfectly matches the planned cross-section, thus avoiding trouble to the rock mass. Click here to know more about this roadheader. Visit www.wirth-europe.com During tunnelling, girders are installed every 0.5 to 1.5 m depending on the conditions then shotcreted to a thickness of 40 cm mixed with metallic pins for added strength.To minimize the environmental impact generated by the works, one of the measures adopted has consisted in installing a concrete waste recycling system, that separates the washing water and the aggregates left in the concrete mixer trucks. Both resources can be reused in the production of new concrete. Also, all heavy vehicles have been equipped with ecological engines to reduce pollution to the atmosphere. Atlas Copco multi-set power generating unitsThroughout tunnelling Acciona opted for six Atlas Copco generating sets installed at the Valencia end of the tunnel. With each rated at 325 kVA, the sets are providing prime power for the Wirth roadheader at the Valencia end, tunnel ventilation and lighting every 15 metres into the tunnel. An identical Wirth roadheader powered by five Inmesol 350 kVA sets is tunnelling from the Madrid end. Visit www.atlascopco.com and www.inmesol.eu Although the roadheader only has a nominal load requirement of 150 kW this more than doubles on start up due to the header's electric motors and electric pump on its hydraulic system. This together with power losses along the electric cable, the tunnel ventilation and lighting every 15 m requires five Atlas Copco sets to meet the initial surge loads.The multi-set installation includes an Atlas Copco Power Management System (PMS) which, once the header is on full load, automatically sharing the load between the five sets, will shutdown sets to meet the required load by -1, -2 or -3 sets. The PMS also controls the sequence of sets start up and shutdown plus the rotation of the sixth standby set, ensuring all six sets operate the same number of hours.The installation also includes Cosmos, installed in December 2007, to provide remote machine status data and advice on maintenance / service requirements, assessing the cost efficiency of an engineer's time travelling to site. Additionally, the Atlas Copco installation also includes a full service / maintenance contract with maintenance being undertaken by the Atlas Copco engineer every 10,000 hours. The Acciona on-site engineer carries out the 5,000-hour maintenance. For the first time in Spain, a 5-year cover plan ensures full fleet management by Atlas Copco plus a five year option buyback.The Atlas Copco installation also features a 10,000-litre fuel tank to automatically top up each set's 477-litre fuel tank by gravity feed. The multi-set power station also includes three transformers, the first to step up to 6,000 V from the generating sets. This is then stepped down, inside the tunnel, first to 1,000 V for the roadheader and again to 400 V for 3-phase common use.The six Atlas Copco QAS325 generating sets had been ordered by Acciona's rental division. The company opted for the rental solution when it found it could not depend on external suppliers, affecting its ability to complete contracts on schedule, and to its satisfaction. 26/08.