The Diabolo project

The accessibility of Brussels Airport by rail is an important step for the Belgian rail network. Thanks to Diabolo, the airport is now directly connected to the major railway lines on the national network and various European cities via international rail corridors. In slightly less than seven years, Brussels Airport has become one of the airports with the best rail access in Europe. The Diabolo infrastructure was officially opened in the summer of 2012.​

Diabolo, a new rail link for Brussels Airport

Diabolo refers to the initiatives we took to make Brussels Airport more accessible by train in order to support the development of the airport and provide an optimal range of sustainable transport. Why a Diabolo? Because the shape of the new rail infrastructure used to open up the Brussels National Airport station is reminiscent of a diabolo toy. That is how this large-scale project got its name.

The Diabolo refers to the new underground rail link between the renovated Brussels National Airport station and the new double-track Schaerbeek-Mechelen line (called line 25N) on the central reservation of the E19 motorway. This new track is 17 km long and connects with the existing rail infrastructure in Brussels using three new bridges and viaducts in the area of Haren and Schaerbeek. Two underground rail branch lines and access ramps connect the new railway line with the tunnel shafts in the direction of Brussels National Airport. Thanks to this new rail link, Brussels Airport can now be reached in just 10 minutes by train from Mechelen and in only 30 minutes from Antwerp. Time gained compared to how it used to be? Half an hour.

In 2005 the airport gained a better rail link with the eastern axis Liège-Limburg-Leuven (line 36). The capacity of this railway line was also increased from the end of 2006 thanks to the 4 tracks between Brussels and Leuven. Since then passengers from the provinces of Flemish and Walloon Brabant, Limburg and Liège save between 15 and 40 minutes when travelling to the airport by rail.


Diabolo Infrabel

Tunnel boring

The construction of the underground rail link between the airport and the new Schaerbeek-Mechelen railway line (25N) was a great engineering feat. Infrabel bored two 1.07 km single-track tunnels 16.5 metres under the airport's most important runways for takeoff and landing. These tunnels were bored using a computer and laser controlled 66 m tunnel boring machine. The air traffic was never affected by this large-scale work.


Safety is our absolute priority. Infrabel is progressively equipping the rail network with automatic stop systems. The new rail infrastructure of the Diabolo and the Schaerbeek-Mechelen railway line (25N) are completely equipped with the European Train Control System ETCS. The Diabolo rail tunnels and the overground railway line have also been equipped with the digital communication network GSM-R.


The Diabolo project involved a total investment of 678 million Euros (2012). It is the first public/private partnership in the railway sector. With this financing method the construction and financing of an infrastructure project are awarded to a private investor. The underground rail link was financed by the project company Northern Diabolo SA. The investment for the overground railway line and the track work and additional work for the underground section was made by Infrabel through public funding.

Next steps?

The completion of the Diabolo project is not the end of the road! Infrabel continues to work on two other strategic rail projects that should benefit access to Brussels Airport. The rail bypass in Mechelen should increase the capacity of the rail link between Brussels, Antwerp and the Netherlands. More specifically, the bypass consists of 2 extra tracks at the back of Mechelen station with two new platforms. The new tracks will connect directly to the new 25N railway line and the Diabolo. The new rail link Watermael-Schuman-Josaphat, which is an integrated part of the GEN project, connects directly the European district to the airport.

Co-financed by the European Union

The new double-track Schaerbeek-Mechelen line (line 25N and its branch lines) was granted EU funding under the TEN-T program (Trans-European Transport Network).

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