Geocon: Ready to go under?

Strukton Survey & Monitoring provides extensive expertise in land surveying, positioning and measurement in complex positioning operations. Geocon, the name under which we operate in the global market, is highly regarded in the immersion industry for both tunnel elements and caissons.

GPS base station 3
Monitoring na afzinken 002

Precarious projects

One of the most high-risk moments in tunnel construction is when the tunnel elements are being immersed. Failure is not an option, as the potential economic losses in the event of increasing delays are too great. When it comes to our ability to perform immersion activities in precarious situations, our achievements speak for themselves. Over the past 30 years, we have successfully immersed more than 130 elements as part of more than 20 domestic and international projects.

Doing more than just the minimum

Providing support in high-risk underwater positioning operations involves more than simply presenting figures. We distinguish ourselves by focusing specifically on how we can unburden our clients. This enables us to provide a wide range of services:

  • Establishment of a geodetic network for determining the positioning of the immersion location and as-built inspection of the tunnel elements
  • Real-time information and visualisation of measurement data for controlling the immersion process
  • Visualisation of lifting capacities, jacking pressures, ballast water levels, undercurrents, etc.
  • Live visualisation of the positioning project via
  • For every project, a measurement system based on our modular systems
  • Immersion without measurement tower and/or access shaft
  • Monitoring of the tunnel elements during and after immersion


  • Project preparations: The best plan and optimised design are our point of departure for successful immersion operations.
  • Risk management: Real-time feedback of measurement data during the immersion process facilitates reliable control of the immersion process.
  • Quality assurance: The demonstrability of the construction process for clients, licensing authorities and insurers.
  • Information provision: To stakeholders in the immersion process, such as the client and
    people in the immediate vicinity. Inextricably linked with the relationship of trust.


Immersion sensors, and therefore also their specifications, are selected on a project-specific basis. Our core responsibility is to provide reliable positioning data. Amongst other things, we use the following to do this:

  • RTK GPS systems
  • Tautwire systems
  • USBL and LBL
  • Mechanical stroke length measurement
  • Total stations
  • Geocon positioning software
  • Video registration

Extensive range of possibilities

In principle, we can perform any type of measurement with our equipment:

  • Rotation
  • Direction
  • Jacking capacity/pressure (tension)
  • Winch force
  • Water level in ballast tanks or surrounding environment
  • Water pressure in immersion joint
  • Flow rate/volume during undercurrent
  • Deformation/joint width
  • Subsidence after immersion
  • Force and/or strain in the tunnel elements, segments or joints