Air traffic plays an ever increasing role in passengers and freight transportation. Good accessibility of the airport is essential to channeling this flow of passenger and goods from and to the airport. TUC RAIL collaborates with Infrabel on improving rail access of Brussels Airport, thus combining the advantages of air and rail to consolidate the strategic position of our country at the heart of Europe.

The Diabolo project is not only a vast but also a very complex project. It consists of improving access to the airport in order to link it to the north (towards Brussels, Mechelen and Antwerp) by constructing an underground rail link between Brussels Airport and the new double-track line Schaerbeek - Mechelen (L25N) on the central median of the E19 motorway. A railway tunnel has also been constructed. It starts at Brussels Airport station (cut-and-cover tunnel of approximately 400 meters in length) and then travels under the runways (bored twin tunnel of 1070 meters in length). The tunnel continues on, first passing under the Brucargo area (a 450 meters cut-and-cover tunnel), and then under the Machelen highway interchange. It then surfaces at the central median where it connects to the new Line 25N.

Work began in October 2007. The contractually agreed date for completion is 25 February. The Diabolo project will be placed in service after the required testing and certification procedure, namely on 10 June.