A footbridge between heritage and lightness: the challenge met at Arquennes

A context rich in history and constraints

On the remains of the old railway viaduct of line 141 in Arquennes, the greisch office was commissioned to design a pedestrian bridge to replace one that disappeared after World War II. The project is located near a listed heritage site, at the intersection of the historic Charleroi-Brussels canal and the Arquennes swing bridge.

A discreet structure designed for users and the site

Rather than imposing itself visually, the footbridge gives way to the landscape. Its design is directly inspired by the old metal lattice structure with 45° inclined meshes, reinterpreted in a contemporary way, without pastiche.

Thanks to a rigorous geometry and a weathering steel lattice of only 30 mm², it achieves an exceptional lightness of less than 75 kg of steel per m² of deck. This performance, rare for this type of structure, reflects advanced section optimization and a frugal approach to resources.

Technical choices dictated by sustainability

Materials: combining strength and aesthetics

The choice of weathering steel ensures excellent resistance to weather without the need for anti-corrosion protection or maintenance. Its warm tone naturally harmonizes with the existing masonry.

The decking is made of FSC tropical wood, with quartz-based non-slip inserts, ensuring comfort and safety of use, including for cyclists and people with reduced mobility.

Guardrails and lighting: safety and integration

Vertical guardrails in weathering steel, enhanced with wooden handrails, ensure safety without affecting visual transparency. Two integrated LED lines provide functional night lighting, complemented by wide-beam projectors that highlight the lattice.

On-site integration and construction principle

Access to the site by land required splitting the structure into four segments of 13.5 m, pre-assembled in the workshop, then welded together on site at the base of the existing supports. This modular approach, combined with the use of reduced lifting equipment, allowed an implementation respectful of a narrow and listed environment.

Remarkable technical and environmental performance

With a deflection under load of 1/600 of the span and a vertical natural frequency of 4.67 Hz, the footbridge meets the strictest requirements for dynamic comfort. Its optimized weight minimizes the impact on the existing supports, reducing interventions on the old structure and limiting the overall carbon footprint of the project.

Read the full article in English – IABSE Congress Ghent 2025 (PDF)