Second tunnel element successfully immersed in the Scheldt

In recent days, the second tunnel element was successfully immersed in the Scheldt near Antwerp. This complex maritime operation demanded the highest standards of precision and safety — failure was not an option.

IMMONTEC is built on two specialised core teams: Immersion and Monitoring. While the Immersion team focuses on preparing and executing the immersion of tunnel elements, the Monitoring team plays an equally vital role in ensuring accuracy and safety throughout the entire process.

Typically, the Monitoring team operates onshore, handling complex civil engineering positioning and measurement systems. However, their expertise is just as crucial during immersion operations, where they provide the real-time data that enables informed decision-making in dynamic environments.

Monitoring during immersion: critical data streams

Throughout the immersion process, a wide range of parameters is continuously monitored, including:

• GNSS/RTK positioning – Real-time location tracking of tunnel elements, pontoons, and other equipment
• Total stations with automatic prism tracking – Continuous displacement measurements at sub-millimetre accuracy
• Pressure sensors and level meters – Monitoring of ballast levels and upward forces on the tunnel element
• Inclinometers and gyroscopes – Tracking of pitch, roll, and yaw movements
• SCADA dashboards with alarm modules – Centralised data visualisation, logging, and immediate alerting of anomalies

A critical phase: the internal positioning measurement

One of the most intense moments in the immersion process is the internal positioning check — the moment when it’s verified whether the tunnel element lies exactly in its pre-defined position. While part of the team rests, the night shift closely monitors this phase. The Survey Supervisor performs the measurements and only gives the final confirmation — the “GO” — once full alignment is assured. This “GO” officially marks the successful completion of the positioning process.

Monitoring team: vital yet often invisible

The Monitoring team may not always be in the spotlight, but their contribution is invaluable. Their precise data collection and interpretation ensure that immersion operations proceed in a controlled, safe, and repeatable manner.

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