The “four locks” project concerns the construction of four new locks: one in Obourg on the Canal du Centre, and three others in Marchienne, Viesvilles and Gosselies on the Charleroi-Brussels Canal. In 2024, works began on the first lock, the one in Obourg. These works are part of a broader plan: the Seine-Scheldt project, which includes the construction of the Seine-Nord Canal. Aiming to strengthen Wallonia’s economy, support the energy transition and enhance the quality of life while reducing road traffic, SPW Mobility and Infrastructure is increasing the capacity of its navigable waterways.
The existing Obourg lock, 96 m long and 11.5 m wide, was built in the 1960s, at the same time as the widening of the Canal du Centre. To meet the growing demand for inland waterway transport, a new lock is being built next to the existing one, with a length of 149 m and a width of 12.5 m. The site is therefore upgraded to the CEMT Va standard (2,000 tonnes). The existing buildings will be renovated and supplemented with new ones.
A two-phase project: new lock and renovation of the existing one
The full assignment – from design to construction supervision – for upgrading the Obourg lock was entrusted to bureau greisch and the architecture firm Canevas.
To maintain navigation throughout the entire duration of the construction works, the project has been divided into two phases. First, the new lock is built; in the second phase, the existing lock is shut down and renovated.
Building a new lock requires excavating down to foundation level to allow construction of the base slabs (radiers). At Obourg, the presence of a confined aquifer and chalky soil makes this initial stage more complex. The chosen solution is an underwater excavation combined with the construction of a watertight concrete plug with anchors, also executed underwater. The retaining structures consist of secant piles and anchors. The excavated area, 195 m long and 15.5 m wide, reaches a depth of 13 m. The next step is underwater concrete placement. Once the concrete has hardened, the water is pumped out and the structural geometry is completed in reinforced concrete. The installation of gantries, gates, valves and other technical equipment then follows.
Standardisation of gates and harmonisation of equipment
A key objective of the client in this lock construction programme was standardisation. To meet this requirement, bureau greisch conducted studies comparing the constraints of all four sites to propose a unified solution. Equipment such as gantries, gates and valves are identical, making maintenance easier and ensuring spare-part compatibility. The geometry of the lock chambers and the typical sections of the lock heads could be replicated. The BIM model, initially developed parametrically, benefited greatly from this ability to reproduce elements. Subsequently, as each site has its specific constraints, technical solutions had to be developed to address all issues encountered. By adopting consistent dimensions and common construction principles, the four sites benefit from a reproducible design that facilitates both operation and maintenance.
Learn more about the standardisation of the gates
Beyond the lock
The project also includes the construction and renovation of buildings, the redevelopment of the surroundings and the road infrastructure that provides access and circulation around the lock site.
The pumping station and storage hall, which date back to the original construction of the lock, will be renovated. To preserve the architectural quality of these buildings from the 1960s, the white glazed brick façade, damaged over time, will be replaced with a similar brick. Openings will be adapted to accommodate new electromechanical requirements. The existing window frames, which remain in good condition, will be preserved and refurbished. The glazing will be replaced with higher-performance glass. New buildings will also be constructed: five technical pavilions housing electromechanical systems, a timber-frame and CLT control building, and a storage facility for the lock gates. The latter features a removable roof to allow the handling of the gates when necessary.
The surroundings of the lock will be redesigned to provide mooring areas. A turning basin will also be created to enable 135-m-long vessels to turn around, which requires a local widening of the canal. Road infrastructure will be upgraded and made safer: the road crossing the existing lock will be rebuilt, and a safe passage for the RAVeL path will be created. As the right bank will be reconstructed, the RAVeL alignment will be completely redesigned.
The actors of the project
- Project owner: SPW Mobility Infrastructure – Seine-Scheldt
- Architect: Canevas – bureau greisch
- Engineering (Structural, Civil Engineering, Building Services): bureau greisch
- Electromechanical Engineering: Tractebel
- Contractors: SM Artes Depret – Artes TWT – Artes Roegiers – TRBA
To go further
Royers Lock, the renewal of a giant
