Tunnel Rehabilitation

Tunnels form an integral part of our infrastructure that we fundamentally rely on and expect to last for 100 years or more. In particular, older tunnels constructed many decades ago reaching back into the late 1800’s exhibit deficiencies typically caused by adverse ground and ground water impacts exerted onto the tunnel linings which often lacked waterproofing protection.  During a tunnel’s use, internal moisture changes further contribute to regular wear and tear.  Many tunnels thus require repair to ensure continued intended use, be it for rail, road or utility. With our extensive experience in tunnel refurbishment, we take a holistic approach to tunnel rehabilitation, not only determining the source of a tunnel’s deterioration, but providing our clients with engineered long-term solutions by applying state of the art tunnel rehabilitation waterproofing and strengthening techniques.

Holistic Rehabilitation Approach

Many reasons may lead to a tunnel’s need for rehabilitation. In some cases structural defects may be discovered that require immediate attention, but more often than not, a tunnel’s state of disrepair is the result of slow and steady leakage or water ingress. At GZ, we take a full-picture look at the problems inherent in a tunnel or station structure so that we can provide long-lasting repair solutions.

This involves a holistic approach in determining the root cause of the problem to understand how to solve it. If a tunnel is leaking, we determine the source of leakage by inspecting the host ground and ground water conditions as well as the structure’s unique characteristics and deficiencies.  We examine the structure for defects and investigate its history and its construction process by examining as-built conditions.  Along with a comprehensive digital tunnel interior scan the sum of this information establishes a comprehensive data base or “Tunnelband” that is used to derive the rehabilitation approach.

Long-Lasting Solutions for Long Lifetimes

Once the root cause of a tunnel’s problem has been determined, we come up with long lasting solutions befitting a tunnel’s long lifetime. We believe in permanent, complete solutions – not just quick fixes. The wide range of rehabilitation options we offer includes complete structural refurbishment with utilization of continuous membrane based waterproofing systems, curtain grouting behind the tunnel liner and liner repair as well as localized measures with structural repair and waterproofing. In developing the rehabilitation solution we are sensitive to the fact that our clients are protective of their infrastructure’s continued, active use.

Our Tunnel Rehabilitation Services include:

• Detailed tunnel condition inspections
• Tunnel or station leakage assessments
• Leak remediation design, ranging from isolated crack treatments to full structure exterior curtain grouting to implementation of drained or undrained waterproofing membrane based umbrella systems
• On site construction supervision and management services for any remediation work
• Expert services for underground water Intrusion
• Development of digital documentation on the as-built tunnel conditions after rehabilitation and layout of a long-term inspection program for structure monitoring