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Diabolo Project, Zaventem Airport

For the future development of the Brussels-Zaventem industrial location 2 infrastructural projects were embarked on, which will enable Zaventem international airport to be accessed more easily from the north. This will add to the airport's attractiveness in terms of both passenger and freight traffic. The "Diabolo" project is intended to convert the current dead-end underground station at Brussels international airport Zaventem into a through station linked up to the new Brussels-Antwerp high-speed route, which is to be set up on the central shoulder of the E 19 motorway. Secondly the E 19's Cargo motorway link will be provided with additional accesses and exits to improve the accessibility of the Brucargo freight airport. An existing motorway bridge is to be renovated and expanded by a new bridge for cyclists. A fly-over is being built to provide direct access to the Cargo area. The two infrastructural projects are connected with one another- representing the first privately prefinanced projects (PPP projects) in Belgium. The core of the Diabolo project are two mechanically driven tunnel tubes each roughly 1,070 m in length, which are to be excavated with a mixshield with 8.32 m diameter with fluid support. The two tunnel tubes possess an external diameter of 8.00 m and are lined with 35 cm thick segments. The maximum groundwater level amounts to approx. 15 m above the tunnel floor. The tunnel tubes are completely located in groundwater. The tunnel excavation takes place in softly bedded soils consisting of fills of fine sands of mixed grains with occasional plant residues and rock intrusions as well as mixed-grain sand layers belonging to the Brussels Formation with clayey and silty elements. Clayey to rocky fine sands are occasionally to be found. The tunnel route runs under aircraft parking aprons, the airport's most important take-off and landing runway and a number of taxi strips. The tunnel safety concept foresees the first cross-passage being produced after roughly ¼ of the excavation length. An evacuation shaft is to be created after excavation midway between the tunnel tubes. An escape tunnel, which is also to be built, leads passengers to an existing underpassage below the take-off runway. A further cross-passage is foreseen between the evacuation shaft and the target shaft. The cross-passages and the connections between the tunnel tubes to the evacuation shaft are to be driven under the protection of ground freezing. In addition roughly 1.1 km of tunnel is to be constructed by the top cover method and approx. 2.3 km by means of cut-and-cover. The project is scheduled to run from November 2007 till mid-February 2012. It is due to go into operation in June 2012.


  • Country: Belgium
  • Region: Brussels
  • Tunnel utilization: Traffic
  • Type of utilization: Main-line rail
  • Client: Northern Diabolo N.V. (PPP Company for the railway tunnel)/Via-Zaventem N.V. (PPP Company for the road building section)
  • Design Planners: TucRail N.V. (Railway)/AWV Agentschap Wegen en Verkeer (Roads)
  • Consulting Engineer: Wayss & Freytag Ingenieurbau AG, Technical Department,Frankfurt am Main (tunnel drive)/Technum (other tasks)
  • Test Engineers: TucRail N.V.and Eurostation N.V. (Railway)/AWV (road)/SECO
  • Construction Supervision: TucRail N.V./Eurostation/AWV
  • Contractor: THV Dialink JV: • CE I-De Meyer NV, Belgium/Wayss & Freytag Ingenieurbau AG, NL Benelux/MBG (VFE NV), Belgium/Vinci Construction Grands Projets, France/Smet Tunnelling, Belgium
  • Main construction method: Open/trenchless
  • Type of excavation: Shield machine (SM)/Top cover construction method/Cut-and-cover
  • No. of tubes: 2
  • Tunnel total length: 5,600 m
  • Cross-section: 54.4 m² (bored diameter)
  • Contract Volume: 322 mill. Euro
  • Construction start/end: November 2007 till February 2012
  • Opening: June 2012