On 28 February 2022, the CIRCUL 2020 consortium and its partners officially completed the renovation of the Annie Cordy Tunnel (formerly the Leopold II Tunnel) for Brussels Mobility, assisted by Egis. With a length of 2,600 metres, it is the longest tunnel in Belgium and a major strategic axis through which more than 60,000 vehicles pass every day, linking the centre of Brussels to the motorways from the north and west of the country.

The Annie Cordy Tunnel has been completely renovated and meets the highest quality and safety standards. First-class technologies were also implemented to ensure optimal maintenance for decades to come.

The work, which started in 2018, was carried out by BESIX, Jan De Nul Group and EQUANS, members of the CIRCUL 2020 consortium, and their partner DENYS. The renovation operations are now followed by a 25-year maintenance period, also entrusted by Brussels Mobility to BESIX, Jan De Nul Group and EQUANS.

An official inauguration and the official name change will follow at the end of May.

Nature of work

The work consisted of a major renovation including the repair of the structural works, the reconstruction of the roadway and surroundings, the rehabilitation and construction of technical premises and 17 new emergency exits, waterproofing, and safety compliance. To assure a long lifetime for the tunnel structure, 24,000m² of cathodic protection was installed.

All the equipment also had to be replaced, including 800 kilometres of cables, ventilation, communication and monitoring installations, as well as the lighting. Finally, the brand new decoration of the tunnel’s interior walls was completely redesigned under the direction of Brussels Mobility and Art & Build.

Challenges of the site

Given the location and strategic role of the tunnel, the work was carried out exclusively at night, from 10 p.m. to 6 a.m., leaving the rest of the day free for traffic. The months of July and August 2018, 2019 and 2020 were the only exceptions, with a complete closure of the infrastructure 24 hours a day. In 2020, during the first Covid-19 wave, the execution of the works was accelerated during an additional closure of the tunnel, which was possible due to lower traffic frequency.

During the night closures, an average of 180 persons per 24 hours were at work on the construction site. At peak times during the complete summer closures, this number rose to about 400 persons per 24 hours working on the project.

The tunnel’s particularly dense direct environment required the construction teams to take into account many unusual elements. Along its route, the tunnel runs alongside public transport, including a metro line, various networks including the city’s sewage system, groundwater, and passes under the Brussels-Charleroi Canal, major boulevards, and the listed Elisabeth Park.

New technologies for state-of-the-art maintenance

Advanced technologies have been used to facilitate the maintenance of the Annie Cordy Tunnel for decades to come. For example, the use of 3D scanners and 360° cameras at several stages of the renovation process provides accurate digital models of the infrastructure as built.

Similarly, the photogrammetric survey of all the concrete slabs and the resulting orthomosaic ensure that the maintenance teams have an image detailed to the centimetre and including geolocalised data. All this will contribute to first-class maintenance.

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