Cutting-Edge Tech Underpins Historic Bordeaux Stone Bridge Restoration
A massive, €50 million project is underway to safeguard the historic stone bridge in Bordeaux, employing both high-tech precision and centuries-old craftsmanship. The multi-year effort, slated for completion in July 2029, aims to protect the bridge’s foundations from erosion and restore its structural integrity.
The restoration, launched in spring 2025, involves a complex interplay of modern engineering and traditional stonemasonry. Teams are meticulously reinforcing the bridge’s base with a “rocky mattress” – a tangle of stones weighing approximately one ton each – placed strategically along the bed of the Garonne River.
Precision Placement with Advanced Mapping
What appears from the riverbank as a simple operation – “a shovel putting stones in the water” – is, in reality, guided by cutting-edge technology. According to Olivier Hauquin, project manager at Bordeaux Métropole, the process begins with precise mapping of the Garonne’s riverbed to identify hollows and bumps.
“From this photograph of the bottom, the crane pilot, installed in his cabin, follows the plan of the bottom on a large screen and positions each rock in the exact location planned,” Hauquin explained. Each movement is guided with pinpoint accuracy thanks to a GPS beacon attached to the end of the crane’s grapple.
Protecting the Foundations
The stones are strategically placed under the bridge structure to protect the Garonne’s riverbed from erosion and “not destabilize the existing foundations.” The teams are adopting a flexible approach, adjusting the placement based on real-time observations. “We see as we go along,” Hauquin stated. “There are areas where we put more than was initially planned and others less. It varies.”
The stones themselves are sourced directly from the commercial port of Bassens and are delivered to the foot of the bridge. As of October 31, work had been completed on two arches upstream and downstream of the bridge, with plans to gradually expand the rocky mattress along both sides of the river.
A Dual Approach: Modern Engineering and Heritage Preservation
While the underwater work progresses, a separate team is focused on restoring the bridge’s internal structure. Stonemasons from the Companions of Saint-Jacques are working through “trap doors” created above the bridge’s piers, meticulously recovering and replacing damaged stones and bricks.
“We mainly do heritage work,” Hauquin noted. “That is to say, we take all the stones and bricks inside the bridge which are broken and fractured, but also the joints which are in poor condition.” This phase of the project is expected to be a long and meticulous undertaking, lasting the entire duration of the restoration.
The current phase follows a previous stage involving the use of large red drills in the summer of 2025. Hauquin confirmed that these drills will return in the summer of 2026 to reinforce additional piers, specifically to facilitate work on the tram platform during planned disruptions in July and August.
Despite the scale of the project, Hauquin assures that the schedule remains on track. The teams are “capable of working constantly,” with weather conditions posing minimal disruption, except in the event of a storm. This historic and ambitious undertaking represents a significant investment in preserving a vital piece of Bordeaux’s heritage for generations to come.