Construction of Aica-Mules Pilot Bore Starts at Brenner Base TunnelThe Brenner base tunnel is a key piece on the Berlin-Munich-Verona-Bologna-Palermo high speed rail corridor, which crosses 10 Italian regions from the Brenner mountain pass travelling along the Tyrrhenian regions to join Sicily. This European corridor is also an important link for long distance freight transportation.The Brenner corridor from Munich to Verona cannot function by itself but only if northern and southern accesses to the Brenner base tunnel are built. For this purpose, the Brenner corridor has been divided into several sections. In Italy, the Ministry for infrastructure has subdivided the project in "priority sectors" that can be completed concurrently with the Brenner base tunnel by 2020-22. The Verona-Innsbruck line has been divided in two projects: the Brenner base tunnel in the north, which is the cental piece of the long-term development of the Verona-Munich railway corridor; the four tracking of the Verona-Fortezza line in the south, to integrate the line into the high speed rail network, in accordance with an agreement signed in 2001 by the Ministry of transport and the Bolzano autonomous province. Brenner base tunnelThe 55 km Brenner base tunnel will comprise two main single-track twin tunnels, connected together by cross passages at 333 m intervals and built 40 to 70 metres to each other according to the geotechical conditions of the rock mass. Each tube will feature a circular cross-section with a 4.05 m radius. Trains will travel at 250 km/h in accordance with European standards. At full regime, 400 trains will cross the Brenner base tunnel each day, whereof 320 freight trains.The north portal of the Brenner base tunnel will be located at the entrance to the Innsbruck station while the south portal will be situated at the entrance to the Fortezza station. The project includes: three multifunctional areas - Innsbruck bypass, Steinach and Prati - built every 20 km and fitted with emergency stops for the rescue of passengers in case of accident and equipment for traffic management and maintenance. All the multifunctional areas will be accessible by a vehicular tunnel from outside; four access adits - Ahrental (approx. 3 km), Wolf (approx. 3 km), Vizze (approx. 3.8 km) and Mules (approx. 1.7 km) - which will serve as access adits for the pilot bore and, in the future, as safety exits for the base tunnel. Construction of the Brenner base tunnel will commence in 2010 and conclude in 2020. Meanwhile, precious data will be collected on the hydrogeological characteristics of the bedrock during construction of the exploratory tunnel, which commenced on 28th April under the future path of the twin railway tunnels. BBE SE (Brenner Base Tunnel Societas Europae) is the European company entrusted with the planning and construction of the Brenner base tunnel and the preparatory works. Italy owns a 50% share in the company through Tunnel Ferroviario del Brennero - whose partners are Rete Ferroviaria Italiana (RFI), the owner of Italy's railway network fully owned by the Italian national railway company Ferrovie dello Stato (FS), with a 83% share, the Bolzano autonomous province (6%), the Trento autonomous province (6%) and the Verona province (5%) -, Austria with 25% and the Land of Tyrol with 25%. The overall planned investment (at 2006 prices) is approx. EUR6 billion. The European Union will contribute EUR593 million. Click here, here and it/103. Visit www.bbt-se.com Aica-Mules exploratory tunnelThe official start of tunnelling of the 10,450 m Aica-Mules exploratory tunnel, which will be driven at about 1,500 m of depth and will be used for mucking-out and drainage when the base tunnel is constructed, took place in the presence of Italian president Giorgio Napolitano, Ferrovie dello Stato president Mauro Moretti, the presidents of the Bolzano and Trento autonomous provinces, Luis Durnwalder and Lorenzo Dellai, and BBT SE supervisory board president Horst Pöchhacker. At the end of 2007, the construction of the pilot tunnel has been awarded to consortium ATB, formed by Pizzarotti (38.95%), Condotte (38.95%), SELI (8.55%), Collini (8.55%), Bilfinger Berger (1.60%), Alpine Mayreder (1.60%), Jaeger Bau (0.90%) and Beton- und Monierbau (0.90%) for EUR78.9 million and a time frame of 30 months.Tunnelling of the first stretch of the tunnel (150 metres) has been achieved using traditional methods. Along with the exploratory tunnel, which will be bored by a double shield TBM, the contract also involves the construction of a 1.8 km intermediate tunnel in Mules, a 400 m connecting tunnel between Aica/Unterplattner and Hinterrigger, the installation and management of the excavated material and the primary and secondary infrastructure. The hopper will load the conveyor belt The exploratory tunnels are divided into six sections: Aica, Mules and Vizze in Italy; and Wolf, Ahrental and Innsbruck in Austria. Their excavation will provide important information on the hydrogeological characteristics to facilitate the construction of the main tunnels and reduce the risks in terms of timelines and costs. TBMThe double shield TBM has been designed, built and supplied by SELI, which for it used some components of a TBM Wirth DS-0630-118. SELI revamped the machine into a double shield universal (DSU) TBM. The DSU TBM has been designed as an evolution of the double shield TBM to cope with rapid squeezing ground, being able to treat and to stabilise the rock ahead of the tunnel face through the combination of piles and special grouting. It is 134 m long and weighs 550 tonnes. The cutter head rotates at 0-7.3 rpm and advances as the engines supply a power of 1,960 kW (7 x 280 kW). The bored diameter is 6.3 m. It is equipped with 46 17" rock cutters. The TBM has capacity to bore 30 metres per day. The advance of the front shield, which holds the cutter head, is made by means of 14 rams that supply a maximum thrust of 25,000 kN. Visit www.selitunnel.comLiningThe tunnel lining will consist of precast concrete segments and/or shotcrete and steel arches. If the geological conditions require to line the tunnel with precast segments, the tail shield, equipped with 19 hydraulic rams supplying a maximum thrust of 34,400 kN, will allow the cutter head to move forward pushing against the completed lining at rear, formed by six 20 cm-thick segments. The segments are manufactured in Lombardy in a facility equipped with a steam system that accelerates the concrete setting.Once arrived to the site, the segments are loaded on a special platform by a gantry crane. Then a second crane, with vacuum grasp, rotates then 90 degrees and transfers them on a mobile platform. Lastly, a mechanical erector places them around the tunnel perimeter. The first segment is positioned at the bottom of the tunnel on a mortar layer while the standard and key segments are placed on the walls and crown to complete the ring. Once a complete ring is shaped, the sealing is done with inert material to fill the annular space around the extrados created by the shield.Rock haulageThe cutters mounted on the face of the TBM cut the rock into chips which fall into a number of buckets on the cutter head. The chips are then stored in a hopper that drops them (up to 700 cu m/hour) onto a conveyor belt system manufactured and supplied by Marti Technik. The belt will be 10,500 m long, 800 mm wide and with capacity for 450 t/h to convey the rock outside the tunnel to a disposal area in Hinterrigger. The rock is granite and granodiorite.The conveyor belt will follow curves radiuses of 400 m, 500 m and 1,200 m. It is powered at 800 kW and equipped with two booster drives that decrease the stress that affects the belt in the curves. The belt will evacuate 304,500 tonnes of rock. Visit www.martitechnik.ch 21/08.