The Castellbisbal Tunnel upgrade in Barcelona is a small section of railway with an outsized role. Set within one of Spain’s most important rail corridors, it helps remove a long-standing bottleneck on the route that links Barcelona and the Mediterranean coast with the rest of Europe. In a place where local movement, long-distance travel and international freight all intersect, improving the tunnel means improving how the wider network works for people, goods and regions.
For this project, NAMA contributed to the renovation and upgrade of the tunnel’s railway system, helping transform an existing ballasted line into a more modern slab-track solution. The work focused on the tunnel itself, where precision, reliability and long-term performance matter most.
Renewing the tunnel for a more reliable railway
NAMA’s role centred on the structural design of the upgraded track system inside the tunnel, supporting a solution tailored to the project’s specific operational needs.
NAMA’s contribution included:
- structural design for the upgraded slab-track system within the tunnel,
- support for the tunnel’s renovation and rail-system upgrade,
- adaptation of the design to a double-gauge railway environment,
- integration of a solution designed for smooth operation and passenger comfort,
- contribution to a line designed for speeds of up to 200 km/h.
While highly specialised in engineering terms, the aim of the intervention was simple in human terms: to make movement through the tunnel smoother, more dependable and better aligned with the future of the wider railway network.
Helping Barcelona, its ports and its rail links work better together
The significance of the project goes far beyond the tunnel itself. Castellbisbal sits on the Mediterranean Corridor, one of Europe’s most important east–west transport axes. This corridor links major Spanish ports — including Barcelona — with inland markets and the wider European rail system. In this context, infrastructure upgrades at key nodes like Castellbisbal help make the network more interoperable, more efficient and more competitive.
The project’s wider impact includes:
- supporting rail interoperability between the Iberian and European standard gauges,
- improving the continuity of the Mediterranean rail corridor,
- helping strengthen freight connections between Barcelona, the Mediterranean coast and the rest of Europe,
- contributing to better links between ports and their hinterland,
- supporting a gradual shift of traffic from road to rail,
- helping create a cleaner and more sustainable transport system over the long term.
In practice, that means a tunnel project in Barcelona can have effects far beyond the city itself — improving not only local railway performance, but also the wider movement of passengers and freight across borders.
Through its work on the Castellbisbal Tunnel, NAMA contributed to a project where careful engineering serves a much bigger purpose: helping modernise a critical rail passage so that Spain’s network can move more smoothly, connect more easily and work more naturally as part of Europe’s shared railway future.
