Caighei Tunnel Breaks Through on Genoa-Ventimiglia Rail DuallingWith a deep roar coming from inside the hill and a loud cracking of rock, the last diaphragm of rock obstructing the Caighei tunnel was pulled down at 12:30 am during Saint Barbara Day on 4th December, 2007. This signalled an important step toward the doubling of the railway line between Genoa and Ventimiglia. The Caighei tunnel crosses the watershed between the Cervo and San Pietro creeks. The 2,693 m Caighei tunnel was tunnelled in record time thanks to the state-of-the-art technology chosen by the project engineers. A 150 m-long tunnel boring machine equipped with rock-grinding rotating teeth drove and lined an 11.84 m-diameter tunnel. The machine advanced through the hill at a constant speed of 15 metres per day, as opposed to three metres per day for conventional tunnelling.The machine was operated by 65 technicians working in shifts all days of the week 24 hours a day. Now the machine will cross the Castello tunnel, dug by means of traditional methods, and transported at the feet of the Gorleri hill, where an even more imposing job awaits it: digging a tunnel of 3,075 m in length towards Impero Valley. Andora-San Lorenzo al mare railway dualling on Genoa-Ventimiglia lineDualling of the Genoa-Ventimiglia line is staggered. Today, 101 of the144 kilometres is a dual track (Genoa-Finale Ligure, Loano-Albenga and San Lorenzo al mare-Ventimiglia). The second phase is underway on the Andora-San Lorenzo section. The San Lorenzo-Ospedaletti stretch opened in April 2001. The preliminary design for track dualling between Finale Ligure and Andora has been approved by the CIPE, the interministerial committee for economic planning. The final design is nearing end.The new alignment from Andora to San Lorenzo will create 19 kilometres of double track, 16 km of which in tunnel and approx. 1.2 km on viaduct, as well as new stations in Imperia and Andora and a stop in Diano Marina. Herrenknecht TBM S-193 at the end of the 2,693 m Caighei tunnel on the new coastal railway Eight tunnels will be bored: four by the TBM (Collecervo-San Simone, Caighei, Gorleri and Bardellini) and four by traditional means, i.e. hydraulic hammer (Castello, Caramagnetta, Poggi and Terrabianca). The longest tunnel is the Gorleri tunnel (3,291 metres). Click here & here.Six viaducts will be constructed on the territory of Imperia municipality. The longest is named Impero and spans 620 metres. The scheme will allow trains to travel at 200 km/h (approx. twice today's speed), which will cut journey times between Genoa and Ventimiglia by half an hour, a significant benefit. Construction has been commissioned to a joint venture of Ferrovial Agroman and Cossi Costruzioni. The entry in service is expected for 2010. The total investment amounts to EUR505 million, whereof EUR319 million for civil works. Visit www.ferrovial.es and www.cossi.comThe TBMThe Herrenknecht TBM, which weighs 1,200 tonnes and is driven by a maximum power of 5,000 kW, has been designed to work predominantly in rocky ground. A thrust is exerted on its 11.77 m-diameter steel cutterhead to advance along the path while the precast lining is installed inside the tailskin of the shield. The TBM has already completed the Collecervo-San Simone and Caighei tunnels. It has still to drive the Gorleri and Bardellini tunnels. Visit www.herrenknecht.comThe shield is managed by a computerised system that activates the electric engines which transmit rotary motion to the main transmission shaft. It is also followed by the back-up or trailing gear, that contains all the services (control cabin, electrical supplies, oil and lubricants, ventilation, cooling) and consist of steel-framed contraptions, known as sledges, set upon rails.The cutting head dressed with 64 disc cutters for rock is positioned at the front part of the machine. Excavated material goes through openings in the face of the machine. The spoils are then taken out to the back and outside the tunnel.The rear part of the shield is fitted with 40 hydraulic cylinders that push the cutterhead forward by leaning against the last positioned segmental ring. The segments are made out of precast reinforced concrete. Seven of them assembled together create a ring, forming the tunnel's permanent liner. These segments are produced in Andora in a plant equipped with a steam system to accelerate the concrete setting. This segment plant has been provided by CIFA. Visit www.cifa.comFrom the plant, the segments are transported by truck to the segment yard where they are stored using a special gantry crane. Subsequently, a second crane with pneumatic grip rotates them 90° and place them on a mobile carrier. Lastly, a mechanical erector positions each segment into place to create the tunnel walls. The first segment is placed on the bottom of the tunnel and laid on a mortar layer. Then, the other six segments are positioned one after the other to create a complete ring. When a ring is formed, inert material and cementicious grout is injected behind the ring to fill the annular cavity which is formed between the tail shield and the segmental ring which is assembled therein. When all the steps are concluded and the 40 cm-thick liner is in place, the tunnel has a net diameter of 10.84 metres.The TBM resumed work in end October after being held up in April because of the lack of adecuate dump sites. Read E-News Weekly 44/2007. Click it/86. 52/07-01/08.