Undergrounding of the Barcelona commuter rail line R2 as it passes through the urban area of Montcada i Reixac (Barcelona). Vallbona variant and Aguas junction
As part of the overall R2 undergrounding project in Montcada i Reixac, this section corresponds to its southern segment. The project is driven by the following objectives:
- Construction of a new grade‑separated connection (flyover) between the R2 line and the Aguas junction line, improving interoperability between the two railway access routes to the northern area of Barcelona
- Construction of a third track to increase capacity along the R2 corridor
- Undergrounding of the railway to eliminate urban and visual impact in the Vallbona neighborhood in Barcelona
The works consist of an initial at‑grade section of 735 meters in length, followed by a second section of 785 meters where a cut‑and‑cover tunnel up to 25 meters deep is constructed to bury the tracks.
The cut‑and‑cover tunnel will be executed using the diaphragm wall (cut‑and‑cover) method: first, the external and central diaphragm walls are constructed in situ, followed by the execution of the roof slabs, and then excavation beneath them to construct intermediate slabs down to the invert.
Rover Group has deployed a hydromill for the construction of the diaphragm walls of this tunnel box. These walls range from 22 to 35 meters in depth and are excavated in rock.
Key figures of the project include 50,000 m² of diaphragm walls, 100,000 m³ of structural concrete, 18,000 tonnes of installed steel, and 500,000 m³ of earthworks.
Currently, the R2 commuter line is used by approximately 135,000 passengers daily. The project must be carried out while maintaining railway service, for which several temporary track diversions are planned.
