The renovation of two bridges on the A41 motorway in Chambéry marks a major milestone in improving traffic flow for more than 50,000 vehicles per day. The operation forms part of a wider regional strategy to ease congestion along a critical transport corridor where traffic from the A43/A41 motorway and the Voie Rapide Urbaine (RN201) converges.
The project required the dismantling of two ageing bridge structures that had reached the end of their service life, followed by the installation of two new road infrastructures, each weighing 550 tonnes. To safely carry out these operations, traffic on one of Chambéry’s busiest roads was fully closed for a two-day period, with traffic diversions implemented in advance to minimise disruption to the surrounding area.
Sarens was responsible for transporting the newly assembled bridge structures from an assembly area located approximately one kilometre from the motorway. The company also handled the removal and transport of the old bridges, each weighing 615 tonnes.
For the operation, Sarens mobilised four sets of 24-axle line Self-Propelled Modular Trailers (SPMTs), totalling 96 axle lines, along with specially designed steel support structures. Two SPMT sets were allocated to dismantling the existing bridges, while the remaining two were dedicated to transporting and installing the new units.
The works were executed using the Accelerated Bridge Construction (ABC) method, which involved pre-assembling the new bridge structures offsite before transporting them to their final position. This approach required precise coordination, as the SPMTs had to cross local roads and a car park to reach the motorway. Once the area was secured and traffic fully closed, the old bridges were removed, the new structures positioned, and the dismantled units transported back to the original yard.
The size and weight of the bridges, combined with limited clearances, strict safety requirements, and the narrow two-day closure window, made the operation particularly challenging.
“Once again, our team has demonstrated high technical and professional expertise and a strong commitment to meeting the established deadlines,” said Tom Jonckers, Project Manager at Sarens. “The coordination effort was essential to ensure the project was completed safely, on time, and with minimal impact on the surrounding area.”
