Tunnels represent significant investments and remain in service for extended periods of time, sometime beyond their intended service life. Their structural, civil and functional systems deteriorate at accelerated levels because of the harsh tunnel environment, in particular water infiltration.

  • Applications
    Tunnels
    Culverts
    Vaults
    Underpasses
    Arch bridges
    Galleries
    Underground structures

Specific challenges

Ideally, the maintenance strategies of a tunnel facility should strike a balance between preventive and on-demand/curative maintenance. When 70 to 80% of maintenance activities are performed under a preventative maintenance approach, it is considered to be good practice.

Refurbishment programs are undertaken when the tunnel is near the end of its useful life or when structural changes or repairs are needed (new regulations, evolution of traffic, fire damages, changing geologic conditions, etc).

Whether it is maintenance work or heavier work, interventions in tunnels bring additional challenges due to the difficult tunnel environment.

Working under reduced light conditions, difficult or limited access and egress, with the potential for exposure to air contaminants and the hazards of fire and explosion, underground construction workers face many dangers. Appropriate risk control plans must be in place and strictly enforced.

For both tunnel users and workers, total closure of all tunnel tubes during refurbishment/upgrading obviously provides a much higher level of safety. But in some cases, the work has to be carried out while the tunnel remains in service, with partial traffic closures, which requires a specific traffic management plan.

With trucks carrying rock and spoil out of the tunnel, working in the tunnel can become difficult due to airborne particles such as silica dust and diesel particulates.

Protective equipment such as breathing apparatus should therefore be provided for the site crew. This equipment will reduce worker mobility and increase fatigue, which in itself presents additional challenges.

Tunnel work involves managing the delivery and storage of equipment, tools and vehicles in a small and confined space.

This requires even greater coordination than on other sites, to ensure that products are delivered just-in-time and properly stored on-site.

Full refurbishment and upgrading services

From specifications to execution

Our solutions and technologies for tunnels & culverts

We offer our services for large-scale repair programs of masonry and concrete railway and roadway tunnels involving substantial engineering input, extended durations or special conditions such as emergency interventions, work under traffic, difficult access, etc.

Nerthe Tunnel France

  • Hydro-demolition (manual or robotic)
  • Large-scale cleaning of surface areas with chipping hammers or high velocity water spraying

  • Condition assessment, using photogrammetry programs
  • Mortar patches
  • Re-bonding of delaminated areas, repointing of masonry
  • Repair, relining and reprofiling by shotcrete
  • Sealing of cracks
  • Cementitious coatings
  • Chemical grouts
  • Resin injections
  • Anti-carbonation coating of concrete

  • Treatment of corroded reinforcing steel
  • Protective coatings
  • Cathodic protection: galvanic anodes, impressed current anodes

Discover more about our corrosion protection solutions

  • Catchment trough and pipes
  • Composite liners, waterproofing membranes
  • Drainage system reconstruction and upgrading

  • Construction of cross passages and safety niches
  • Fire protection

  • Bar and strand anchors
  • Soil nails and rock bolts
  • Micro-piles
  • Metal stiffeners
  • Mortar spraying
  • Very early strength dry shotcrete
  • Wet sprayed Ultra High Performance concrete

Discover more about our structural strengthening solutions

Glasgow metro, United Kingdom
Glasgow metro, United Kingdom

Refurbishment of 8 km of tunnels without traffic interruption by working night shift only

/ Solutions provided:

  • Void injection with cementitious grout (3,000 m3)
  • Treatment of water ingress by resin injection (20,000 holes)
  • Repair of concrete defects with wet sprayed mortar (1,700 m2)
  • Cleaning of linings, trackbed and drainage areas

Enlargement of masonry railway tunnel for electrification

/ Design&Build contract:

  • Hydrodemolition
  • Dry shotcrete confinement
  • Ground anchoring and void injection
  • Construction of stiffeners with shotcrete
  • Reinforced shotcrete liner
Roche de Condrieu tunnel, France
Amsterdam metro tunnel, The Netherlands

Fire protection of the stations of the railway tunnel

/ Solutions provided:

  • Protection of steel and concrete structural members
  • Protective plates
  • Sprayed mortars

Discover our case studies

Repair
USA

Baker-Barry Tunnel

Renovation of an historic tunnel in the USA demanded a balance between improving its condition, and retaining unique features; Freyssinet worked with the owner to find the right solution.
  • Tunnels & Culverts
Repair
France

Barbazan culvert reinforcement using UHPFRC

A specially developed mix and custom-designed equipment now allow ultra-high-performance fibre-reinforced concrete to be spray-applied, opening up a world of possibilities for this durable material.
  • Tunnels & Culverts
  • Steel structure retrofitting
  • Asset integrity management
  • UHPFRC reinforcement
  • Innovation
+3
Repair
UK

Channel Tunnel concrete repairs

Mobilisation on a momentous scale paved the way to an early finish on the extensive concrete repairs needed to put the Channel Tunnel back into operation after a devastating fire.
  • Tunnels & Culverts
  • Structural strengthening