Unibridge® : replacing and repairing old bridges

MATIÈRE’s expertise in Unibridge® bridges goes far beyond the design and construction of new structures. The company also has real expertise in replacement and repair, offering its customers competitive and quick solutions.

In West Africa, some bridges built several decades ago are in an advanced state of deterioration, representing a danger for the population and a risk for the economy. The stakes are high, as these infrastructures are often the only possibles ways for inhabitants to reach major cities and to transport goods. 

Replacement of obsolete bridges with Unibridge® structures

In January 2021, MATIÈRE will start work on replacing two dilapidated bridges over rivers in southern Senegal. This project is part of its contract with the Senegalese government for the construction of 18 bridges and overpasses (Plan Sénégal Emergent). These two high-risk structures will be replaced by more resistant and wider Unibridge® prefabricated metal bridges, which will be extended from 1 lane to 2×1 lanes over a distance of 120 metres to facilitate mobility.

A turnkey solution

MATIÈRE’s involvement is not limited to the construction of the structures: it covers all stages from design to delivery of the bridge in order to offer the client a turnkey project. “The studies and foundations are entrusted to specialised local companies because this is not part of our trade. However, we closely monitor, control and coordinate them. These upstream phases are key to the success of such projects,” analyses Thomas Rivalta, project manager. For bridges over waterways, hydraulic studies are necessary to know all the parameters of the foundations and supports precisely. Depending on their condition, we decide whether or not to place the new structure on the existing supports. MATIÈRE relies on its factory in Diamniadio to prefabricate the reinforced concrete parts of the structures and on its local agency to manage the project and coordinate the various stages, from supply to on-site assembly of the Unibridge® bridge components. “Prefabricating the reinforced concrete parts and the structure ourselves guarantees perfect control over quality and deadlines,” explains Thomas Rivalta.  This optimal organisation, which combines MATIÈRE’s know-how with the local economic fabric, is one of MATIÈRE’s great strengths.

Safe engineering structures

Unibridge® modular bridges are particularly well suited to the needs of African countries. Resistant and requiring little maintenance, they are perfectly suited to extreme maintenance and climatic constraints. Other advantages: the transport of Unibridge® components in containers to areas that are difficult to access and the ease of assembly thanks to the absence of on-site welding are real pluses in Africa. By replacing obsolete bridges with Unibridge® bridges, we can guarantee quality bridges with virtually no maintenance, which is a fundamental aspect in Africa,” emphasises Frédéric Bay, export sales manager. We are also contributing to the economic development of the country, since we are restoring damaged or even dangerous routes with safe engineering structures. “

Sabang bridge repair in the Philippines: a textbook case

The repair of the Sabang bridge is certainly the most emblematic example of MATIÈRE’s know-how in terms of bridge repair using Unibridge® solutions. Located 180 km from Manila, this nine-span highway bridge was in danger of collapsing due to a strong deflection in its main span. Commissioned by the Philippine Highway Department, MATIÈRE decided to repair the bridge with Unibridge® structures rather than rebuild a new bridge. A clever solution that turned out to be faster and cheaper than the competition! 

Perfect control of each stage

The first step was to identify the problem. We realised that the deflection of the span was the result of an assembly error during the construction of the bridge eight years ago,” analyses Claude Valdenaire, Bridge Engineer. This diagnostic phase is crucial, because repairing an engineering structure means first and foremost analysing the pathology. “MATIERE then destroyed the damaged span using a controlled explosion. This was a daring idea that was entrusted to a subcontractor with expertise in this field. 

The next step was to replace the damaged span with a Unibridge® mixed structure. “In general, we install steel structures by craning or launching. But the length of the span (60 metres) meant that we had to launch a temporary truss bridge over which the lorries carrying our Unibridge® beams were travelling.  Mastery of the preliminary studies, choice of the best subcontractor for the explosion, speed of execution, high level of prefabrication of the Unibridge® beams … the repair of the Sabang bridge is a true demonstration of MATERIAL expertise! Completed in just five months, it was a first for the company and enabled the client to benefit from a solution that was three times faster and half the price of competitors. The demand for Unibridge® is growing in the Philippines,” says Claude Valdenaire. Customers appreciate our responsiveness as well as the attractive design and fast assembly of our structures. Their resistance to earthquakes makes them particularly well suited to the Philippines, a highly seismic region. “