The Story: Overcoming River Tunnel Flooding Risks

In the heart of Basel, Switzerland, a critical infrastructure project was underway—maintenance and upgrades to a 1.4 km river tunnel running beneath the city. With this tunnel vulnerable to rising river levels, the challenge was clear: how to safely perform maintenance while keeping the workers dry and protected.

The city of Basel needed a flood defense solution that would protect workers against fast-moving river water while allowing continuous repairs in this high-risk environment. The project, planned to span two years, required a system that could handle significant water volumes while remaining operational throughout the entirety of the maintenance process.

AquaFence was called upon to deliver a tailored flood protection solution that would meet both the safety and logistical demands of the project.

The Challenge: Flooding Threatens Critical Tunnel Maintenance

The project faced a variety of unique challenges:

✔️ 1.4 km tunnel under the river, with constant flood risks due to rising water levels.
✔️ Ongoing maintenance work needed to be carried out over two years, requiring a flood protection system that could remain active and reliable throughout the project.
✔️ The requirement to funnel water along one side of the tunnel to create a dry and safe zone for repairs.

With the tunnel entrance needing to be enlarged and constant water flow threatening to hinder maintenance, the city needed a solution that would ensure both safety and efficiency while the repairs took place.

The Solution: Custom Flood Barriers for Maximum Protection

AquaFence’s engineers worked closely with the city of Basel to design a customized flood protection system that would protect workers and facilitate uninterrupted maintenance work:

• Combination of standard and custom-engineered barriers to tackle the diverse challenges of the tunnel’s layout.

• 200 meters of flood barriers deployed in stages, allowing the maintenance project to proceed in seven phases, each addressing 200 meters of tunnel at a time.

• Cost-optimized solution that met the project’s flood defense needs while keeping the overall budget manageable.

• Two site reviews conducted to ensure all challenges and details were accounted for, ensuring smooth implementation.

AquaFence’s flood barriers were designed to be easy to install, move, and operate, providing maximum protection with minimal effort, allowing workers to stay focused on their tasks.

The Results: Safe, Efficient, and Reliable Maintenance

The outcome of this tailored solution was a win-win for the city of Basel and the maintenance teams:

• High safety margins built into the AquaFence system ensured that workers were protected from the fast-moving water running through the tunnel every second.

• The simplicity of the AquaFence barriers allowed for easy deployment and operation, making it effortless for workers to adapt to the new flood mitigation system.

• The project was successfully carried out in seven stages, with each section of tunnel protected efficiently, ensuring ongoing maintenance was completed without delays due to flooding risks.

• The solution was cost-effective while providing a durable, long-term solution to future flooding challenges in the tunnel.

AquaFence delivered the peace of mind that Basel’s city engineers and maintenance teams needed, ensuring that the project was completed safely and on time.