Slipforming Madrid's metro

The dragados and tecsa joint venture (JV) has used several Wirtgen SP 500 slipform pavers to construct 5 km of new metro line between Madrid's Atocha and 'Nuevos Ministerios' stations.

Construction of the slab track was influenced by several conditions. Firstly, the entire 5 km runs underground, which meant paving under extremely confined conditions. Secondly, a decision was made to use wireless control – two Leica TPS 1200 total stations – during construction. This accelerated completion of the project and reduced surveying costs. Lastly, paving could only take place during the night.

The new tunnel has a diameter of 8,43 m. To enable construction of the slab track, the tunnel floor was filled with a 1,5 m thick layer of concrete, leaving just 7,31 m for paving the tracks. The SP 500 paved the slab track in two separate 3,35 m wide track profiles at a maximum thickness of 450 mm.

Because the concrete profile reached right to the tunnel wall it was not possible to use the SP 500 on its four crawler tracks – there was simply no room for the rear right track. However, the SP 500's modular construction meant a three-tracked paver could complete the job. To compensate for the missing track a counterweight was mounted on the lifting column of the crawler unit on the diagonally opposite side.

With construction only taking place at night the J V was only able to work for 9 hours per shift. However, working for six weeks in each direction the work was finished ahead of schedule.