Bridges and viaducts

More than 2,000 bridges, viaducts and tunnels in the structuring network are regularly monitored. They are usually inspected every 3 years, but this interval may vary from 6 months to 6 years, depending on requirements.

Highway structures are classified in different groups based on their condition :

  • Group A: Dangerous structures with very serious defects for which repair is top priority
  • Group B: Structures with serious and evolving defects
  • Group C: Structures with defects
  • Group D: Structures that need to be monitored closely
  • Group E: Structures in a satisfactory state of service that require some maintenance work
  • Group F: Structures with no defects

This classification determines the priority of the intervention. The rehabilitation, reinforcement or replacement of these structures is usually very complicated, in terms of design, preparation and realisation of works.

Therefore, these works often last a long time (the largest works can last up to 3 years). Furthermore, many different techniques and materials are used (concrete, resin, waterproofing courses, repair mortar, etc.) for which the implementation is very dependent on weather conditions and which have to be applied very carefully by specialised technicians.


There are over 40 tunnels in the SOFICO network: they are constantly monitored to ensure they are safe and in proper working order. A vast renovation plan has been drawn up to assess the infrastructures and electro-mechanical equipment requirements and to define the safety measures and different service levels that need to be implemented in each tunnel.

This study divided the tunnels in the structuring network into four categories, according to whether they belong to the Trans-European network and according to their length :

  • Tunnels in the Trans-European Network (TEN)
  • Tunnels of between 500 and 1000 m
  • Tunnels of between 300 and 500 m
  • Tunnels of under 300 m

Sub-categories were also created, dividing tunnels according to each tunnel’s role in the network, the context and the traffic.

More than 2,000 bridges, viaducts and tunnels in the structuring network are regularly monitored.

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