Lovat Begins Tunnelling of Seville Light Rail'La Giralda', the Lovat TBM ordered for Line 1 of the Seville light rail, has begun tunnelling on 11th August, 2005. The machine will bore 2 x 2,500 metres between Parque de los Principes station, in Los Remedios district, and San Bernardo station. Tunnelling is scheduled to take 16 months until December 2006.Tunnelling began from the launch shaft built at Parque de los Principes station and the TBM will cut through Plaza de Cuba, Puerta de Jerez, Prado de San Sebastian and San Bernardo stations. Once it breaks through into San Bernardo station, the machine will be removed, disassembled and brought back to Los Remedios to drive the second tunnel. A noteworthy difficulty will be the crossing of a river. The earth pressure balance shield is expected to drive the 640 metres that separate its starting point from the edge of the docks by the river in about two months. The machine has a length of 95 m and a diameter of 6.05 m. It is 10 m long and weighs nearly 700 tonnes. It is characterised by a rotation speed of the cutterhead of four rev/min and an advance speed of 100 mm per minute. Its 2,100 MW electric power is the equivalent of the consumption of 400 homes. Its thrust capacity is 5,000 tonnes. The TBM is equipped with sensors to detect the presence of gas and progresses by means of a laser guidance system. The TBM will first be working for 12 hours daily and then 24 hours non-stop later on, every day of the week. The machine, which cost is about EUR9 million, will be able to drive between 10 and 18 m of tunnel daily, once the first stage - ranging from 45 to 60 days - has come to an end. During that "learning" period, the TBM will excavate at a speed of seven metres a day. This will allow to catch up all the delays registered by the construction of Line 1. The delays are to blame on several causes, such as the finding of archeological remains, difficult ground or the impossibility to access to specific areas of the works.Ten to fifteen workers will work, in three shifts, in the heart of the machine, whereas another seven or eight will be busy outside. All the workers employed on the job received training courses on the working of a TBM. The real working time of the machine is 50% of the operating time, since 25% is dedicated to excavation, another 25% to the erection of the segments and the remaining 50% to the supply of materials and small adjustments. In addition, when holing through into each of the future stations, previously excavated, there will be a technical break to do the maintenance of the machine. The machine will install a total of 3,420 concrete segments making the lining of the tunnel. The inner diameter will be something more than five metres. Each linear metre of tunnel will generate a volume of spoil of 40 cu m. For each metre of soil crushed by the TBM, four trucks will be necessary (at least 40 trucks will be required daily) to haul the muck transported by a conveyor belt and muck cars to the rear of the tunnel.The 2,500 m tunnels will provide a connection, through Barrau street, with the existing tunnels in Nervion district, which are undergoing refurbishment to be used as part of Line 1. The TBM has been specially designed to avoid water ingress problems encountered in the 1980s when it was first attempted to build a metro line in Seville. View a video here on the assembly of the TBM in May. Click here for more information. Read E-News Weekly 32/2002. Click es/82. Visit www.lovat.com and www.metrodesevilla.net 37/05. Concepcion Gutierrez, councillor for public works at the Andalusian government, and Alfredo Sanchez Monteseirin, mayor of Seville, during the launch ceremony of the Lovat TBM in Seville.