Securing and Repairing the Lavapesson Bridge
The Lavapesson bridge was built between 1968 and 1970 and is located in the town of Granges-Paccot at the Fribourg-North junction with the N12. It is cross shaped to connect the various access ramps to the highway and to let the Morat-Friborg road cross the highway and the Lavapesson stream. This prestressed reinforced-concrete structure has a total length of 230 m (755 ft.) and is divided into three parts by two half-joints.
The structure is generally in a deteriorated state ; in particular, rebar corrosion was confirmed when inspecting the half-joints. Since the central part of the bridge could fall, an emergency measure (SoMa measure) was performed in 2016 to ensure the safe use of the structure until the concreting joint work (VoMa measure) planned in 2018. For this, 27 m (89 ft.) wide centerings were placed under the main deck to suspend the portion of the span located between the half-joints.
The bridge is refitted without compromise. As a result, access chambers were created at the abutments. In addition, bearings, expansion joints and all the curbs are replaced. The structure is enlarged by 1.05 m (3 ft. ) on each side to widen the traffic lanes and create a wider and safer sidewalk. The deck enlargement is made of reinforced concrete supported by UHPFRC struts arranged between the deck slab and the webs. Bridge traffic is detoured in phases to perform the work.
Ramp rehabilitation is done without traffic because they are too narrow. Therefore, two temporary bridges, measuring 65 m (213 ft.) and 90 m (295 ft.) long, were built next to the ramps. The temporary bridges are designed using a steel-concrete composite structure to be easily demolished at the end of the works. The ramp stabilization work consists of removing the expansion joints, creating semi-integral abutments and replacing the curbs.
The concrete is stabilized, the entire waterproofing membrane and pavement is refitted, and equipment is replaced on the entire bridge.
The securing and repairing works on the Lavapesson bridge will create a monolithic and robust structure.