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Barcelona Metro Line 9/10 Expansion, Barcelona, Spain

Spain Projects

Barcelona Metro Line 9/10 will be Europe’s longest underground line at 48km overall. 44km will run through bored tunnels and 4km on an elevated viaduct. Due for completion in 2021, it will provide links to four suburbs as part of a wider urban regeneration programme, connecting the airport and city centre. The project is being delivered in an environment three times more densely populated than London.





£1.3bn (multiple contracts)


2002 - 2021


Design & Build

Barcelona Line 9/10 is the world’s first fully automated driverless metro system. We are delivering three of the four sections of the new line with the scope of our works including 14km of 9m diameter twin-bore tunnels; 13km of 12m diameter single bore tunnels with tracks on two superimposed levels; 26 step-free stations and a train depot. We also had overall architectural responsibility for stations, developing an architectural vision to ensure that all design elements were aligned with a compelling, coherent design philosophy.

The design and construction of Line 9/10 involved the integration of multiple technologies and the co-ordination of many suppliers. We collaborated at the design stage with the client and metro service operator to select a trackform that complied with noise and vibration requirements. We collaborated with Barcelona Technology University, working with them to implement the innovative construction technique of reinforcing the shafts at the stations with steel fibres.

Line 9/10 runs below heavily populated, environmentally sensitive locations throughout the city. Adjacent metro lines remained fully operational during construction due to our extensive monitoring regime, allowing very precise prediction of settlements. The alignment also fell within the Zone of Influence of 18,000 historical building foundations, which were monitored in real-time and achieved settlements well within acceptable tolerances.


  • We helped pioneer the two-tier railway design that enabled us to thread 13km of the new twin-bore tunnel through Barcelona, safeguarding the city’s high value and historic assets
  • To avoid the disruption of constructing additional shafts for changing the TBM cutting heads in heavily congested areas, we used a ventilation shaft to perform a horizontal underground change – the first underground change of a cutter head ever performed. This innovation avoided a two−year exercise to construct a 65m temporary shaft
  • We minimised noise, vibration and dust by installing acoustic dampening, designing micro-blasting procedures to decrease the level of vibrations and reducing the velocity of the TBM when crossing rock to minimise vibrations to neighbouring homes
  • We designed lift−on, lift−off precast topping slabs for use on access shafts when not in active use, permitting vehicular traffic to run across the top when they were not in use facilitating traffic movements
  • The stations were constructed using an innovative vertical cylindrical design that intersected the tunnel, minimising disruption to residents and local businesses by avoiding open cut excavation, reducing the programme and minimising the ground-level footprint


  • 27km of twin-bored tunnels
  • 26 stations step-free
  • 500 functional interfaces with the metro system managed successfully
  • 3xTBMs deploying four different types of cutting wheels
  • 12m diameter TBM
  • 3x more densely populated city compared to London
  • 1,100+ workers onsite at peak

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