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Brand new extensions

Metro building : Madrid

Madrid's programme of extensions is costed at Psts 344,200M (£1.4bn) against the £1bn spent on the first phase but it will have fewer stations - just 26. However eight of these will be interchanges against just four in the previous project.

The extra cost is due to the whole length being in tunnel - phase one included an 18km above ground suburban rail line built in conjunction with the railway operator - and because depots are required for the new line. 'We didn't have to build any in the first section', says Melis.

Main elements comprise the 40.5km loop of the Metrosur, divided into five major TBM tunnelling contracts and one smaller cut and cover job; the extension of Line Ten which will connect to the main system; and Line Eight to the airport.

Exacavated diameter of the double track tunnel is 9.4m while the final internal diameter is 8.4m.

The Metrosur contracts all include sections in 'false tunnel' built between diaphragm walls or in open trench, some open cutting.

On the Line Ten extension one contract is tackling the 6.7km of new line while another will widen the existing tunnel for new higher capacity rolling stock. Voltage is being upgraded to 1,500kV from the 600kV now used on the main system.

Final part of the programme is the extension of the airport line.

This was originally built inwards toward the city from the airport but stopped short of the centre - passengers had to change onto an older line to complete the journey.

A new 5.9km tunnel brings passengers directly into the city centre reducing the journey time substantially.

Two new stations are included in the contract, one an interchange with another line and the other a remodelling of the terminus Nuevos Ministerios where the line will interchange with two other metro lines and four suburban train routes. The new station will also provide in town check in facilities.

TBMs from the first phase are being deployed on this work. They include three Herrenknechts and 2 Mitsubishi/NFM machines which excavate 9.4m diameter and a smaller diameter Lovat working on a small section of single track double bore tunnel.

The extension to the new Line Eight, the airport line, is being finished by the 'Madrid method', because a tunnel boring machine (TBM) which did the first 2km of the drive inwards to the city centre is needed on another contract. Availability of machines has meant some juggling with methods.

But for Melis the EBP tunneller is the ideal. Complaints about its initial high cost fail to take into account the cost of potential long delays, he says.

Madrid has even insisted that contractors supply higher end specification machines. Bidders proposing machines with 1,500mt torque were told to go away and get 2,000mt 'or they would not get the work'. One Herrenknecht machine boasts 2,300mt of torque.

Similarly, the machines were required to have 10,000t of thrust rather than the more usual 6,000t. 'It costs nothing - 5% to 10% on the machine and you can just push your way out of trouble' says Melis.

Other 'certainty' features included doubling the number of tail grouting pipes to avoid blockage and the risk of settlement from an unfilled annulus around the segmental lining.

'The philosophy is safety and redundancy, ' he says.

Money should also be spent without restriction on the relatively small expense of ground investigation and instrumentation he adds. 'That way the engineering team has the best information for negotiating with the contractors as problems arise. No-one pulls the wool over anyone's eyes.'

Madrid has built up some 8,000 measuring points on buildings and in the ground. Data is recorded using a variant of a GIS computer system with each instrument accessible by a double mouse click on a detailed map.

'We give our thanks to Bill Gates, ' says Melis, who preferred the team to develop its own Windows based software rather than bring in expensive systems from a supplier. His colleague Ildefonso de Matias, who coordinates all the electrical and mechanical works, spent three months early in the project working on the software with a team of programmers.

Information is crucial for the informed, fast decisions the pair believe are critical to avoid problems, especially where costly lawyers might become embroiled. 'You have to try and foresee the problems and reach an agreement with the contractor even before it emerges, ' says de Matias.

'We try to take a decision within 24 hours' says Melis. For that to happen means the best political backup and he says he is indebted to Luis Cortes, the current transport minister in the Commundidad de Madrid for fast and positive support (see box).

'As an example, we were able to change the route line at one point within a day because of objections by some residents to the location of a station.'

Decisions are speeded by having a tight management structure. There are only three senior engineers in Melis' team.

For support they draw on 10 senior engineers, nine mid level and 20 other technical personnel in the civil engineering department of Madrid Metro and a similiar number in the electrical and mechanical section. Madrid Communidad's own department of infrastructure provides nine senior engineers, seven mid level and 11 general technical personnel.

'The work is very simple if you have a good clear idea of what you are doing' says Melis.

'You do not need layers of people but direct communication and co-ordination.' He thinks outside project consultants overcomplicate the picture rather than solve problems, particularly when local engineers are skilled and experienced.

Working directly with de Matias, he has been able to coordinate the programme for E&M installation with the civils works. Techniques such as installing the rigid overhead catenary line before trackwork is finished, or for putting in the the escalators in while the civils work is still under way, have been worked out.

'All the trades overlap and work alongside each other, ' says de Matias. The train test operations can begin three weeks after the end of tunnel construction.'

Simplicity and directness are also key aims in the design at every stage. Melis is opposed to using architects to create complex station designs.

'No-one on the way to work at 6.30am is interested in fancy finishes' he says. 'They want to get to the platform easily and for the train to come.'

An exception he grants is the new airport station integrated with the Barajas air terminal, which could be seen as the doorway to the city. The in-town check in will also get special treatment. Otherwise basic layout rules for simple station access are used.

Contract list

Line Eight Ferrovial-Agroman/Necso/ACS £111.7M Line Ten FCC/Ferrovial-Agroman £40.5M widening Line Ten Necso/FCC/Dragados £95.4M New line Metrosur 1. Alorcon ACS/Vias £143M 2. Mostoles FCC £100.7M 3. Fuenlabrada1 Sacyr/OHL £38M 4. Fuenlabrada2 Necso £95M 5. Getafe Ferrovial-Agroman £100.7M 6. Leganes Dragados £111M

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