Project Brussels, Belgium

The Leopold II tunnel in Brussels

Progress of works

The months of July and August, which are synonymous with holidays in Western Europe, were the ideal period for BESIX and partners for major works in the Leopold II tunnel in Brussels. This 2.6 km tunnel is a major traffic artery which links the motorways from the west of the country to the centre of the capital. These works are at the same time a fine example of the one-stop-shop collaboration within the group. During these two months, BESIX Infra (a BESIX entity specialising in roadbuilding) was the leading subcontractor on the project. Van den Berg (a BESIX entity specialising in cable and pipe laying) also contributed, in particular for the installation of several kilometres of service ducts for services in the footpaths. “Each to his own speciality!”

Successful consortium

The CIRCUL 2020 consortium, with BESIX, Jan De Nul and Engie-Fabricom, has been working since 2018 on the Leopold II tunnel which needed to be tackled urgently owing to wear and tear.

Night work

It is only during the months of July and August that the tunnel can be closed completely, enabling the works to be organised optimally and the crews to work around the clock. Work only takes place during the night after 10 pm from September to June, with the tunnel having to be operational again every morning at 6 am. This constitutes the leading logistical challenge for the project as well.

Works on roadway and tunnel

The leading activity during the 2019 summer holiday period was breaking out and rebuilding 50% of the roadway. All drainage chambers were modified and the footpaths, in which several kilometres of service ducts and fire mains run, were renewed both sides of the roadway. What’s more, the team took advantage of the complete tunnel closure to make substantial progress on the renovation works on the tunnel ceiling. This involved not only repairing the concrete and applying a watertight coating, but also applying fire-resistant cladding.

Major civil works

Major civil works were also carried out in addition for the construction of new emergency exits and plant rooms. Three newly built emergency exist were commissioned when the tunnel was reopened on 2 September 2019, enabling renovation of several existing emergency exits to be started in a subsequent phase. Several major items of technical equipment, including high-voltage systems, transformers and extractors were renovated.

Sizeable challenges

Opening the tunnel to traffic on a daily basis during the period from September to June is not the only challenge for the project. Far from it. This 2.6 km-long tunnel passes under the Brussels-Charleroi canal, runs alongside and crosses underground stations and metro lines, water pipes and the city’s sewerage system. On the surface above it there are densely built-up areas as well as a protected park, the Elisabeth Park in the vicinity of the Koekelberg Basilica.

All completed items, such as emergency exits, are required to comply with a whole raft of specific obligations. They are major challenges, each and every one of them, which make the project both difficult and especially interesting”.

The months of July and August were highly intense, presenting us with an opportunity to complete large-scale works, some of which are simply impossible during the rest of the year on account of heavy traffic. Our crews worked around the clock 7 days a week. They did a splendid job.

Bram Vandewalle
Project Manager

Over 5 days 10,000 tonnes of concrete and asphalt paving were broken up and removed to a recycling facility outside the city. Organising this haulage fleet without impeding progress of the demolition works and maintaining the tight schedule constituted an exceptional logistical challenge with was prepared meticulously. The fact that it is succeeding in practice too is large feather in their cap for the team who worked together on it.

Bob Dierick
Project Manager

Project details

Project name

The Leopold II tunnel in Brussels


Road works, Sewerage and drainage, Environment and Surroundings


Brussels, Belgium


SM CIVIL2020 (The entire project was commissioned by the Brussels Region)

Building Period

2019 - 2021

Total value

€ 218 million

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