Security guard at Gartnerløkka

Cautus Geo is monitoring the groundwater and sheet piling for the E39 project in Kristiansand. “Automatic and continuous monitoring provides peace of mind,” says Francois Bonnafous, project director at the main contractor Eiffage.

The French company Eiffage Génie Civil is the main contractor for the major transport project in Kristiansand. The new main road through the city is 1.4 kilometres long and is a comprehensive and complex transport project. It involves more than just a new through road. New railway tracks, a new railway tunnel, new routes for pedestrians and cyclists, and roundabouts and junctions where trains pass beneath newly built roundabouts for local and long-distance traffic are also to be established. The project is estimated to cost 5.2 billion kroner. Everything is due to be completed by 2029.

“The project is complex, even beyond the geotechnical aspects. 40,000 vehicles are set to pass through the area every 24 hours, even whilst the new transport system is under construction,” says Bonnafous.

Real-time data

Cautus Geo provides real-time data on the groundwater and the condition of the temporary steel pipe sheet pile walls – also known as sheet pile walls – which ensure the safe flow of traffic on the motorway through the city.

12 pore pressure gauges, SAA inclinometers, a total station, monitoring prisms, a settlement plate and load cells collect data continuously. All measurement data is analysed in real time by Cautus Web, where it can be viewed as raw data on an ongoing basis.

“Alarm thresholds can be set. When triggered, alerts are sent via text message and email, and all work can be halted whilst measures are assessed and, if necessary, implemented,” says Bjørnar Nevland Knudsen of Cautus Geo.

The instrumentation is in place. The system has been set up. Much of this will subsequently be transferred to the next phase.

Transport package

The Gartnerløkka–Kolsdalen section forms part of the transport package for the Kristiansand region and has been given the highest priority in Transport Package 3. The project is very extensive.

Eiffage was awarded the turnkey contract in 2023. Work began in 2024. Everything is due to be completed in 2029. By then, seamless solutions will have been built for traffic on the E18/E39, good access and exit arrangements will have been secured, a new main cycle route through the city will have been built, a new railway line to the industrial area will have been secured, and a new road link to the port will have been established.

Every city has local transport services. In Kristiansand, these will work in tandem with regional transport and road, rail and ferry services to and from Europe.

– We want traffic to flow as smoothly as possible whilst we’re building new infrastructure. There will be several diversions along the way, and some roundabouts will be temporary to ensure good traffic flow during the construction period. So far, everything has gone well, says Bonnafous.

Major changes

There’s a lot going on in Kristiansand at the moment. Cautus Geo has also provided surveying services for the construction of the new container port. Land will be reclaimed from the sea there, and a new access road will be linked to the road network at Gartnerløkka.

Norconsult is the geotechnical engineer for that project.

– When carrying out large-scale land reclamation projects at sea, it is important to monitor how the seabed reacts to the load. The instrumentation provides real-time data on deformations. This enables us to detect any movements as early as possible and ensure the work is carried out safely, says geotechnical engineer Carl-Fredrik Davidsen.

A lasting solution

Monitoring of the temporary steel pipe sheet pile walls that have now been erected will provide real-time data for as long as work is carried out on this section. Similar arrangements will subsequently be put in place at other locations where the E39 runs along an open stretch of road. There too, sheet piling and a new retaining wall will secure the existing road.

“It’s all about having safe and secure solutions,” says Bonnafous.

Groundwater monitoring will also continue over several months.

– Falling groundwater levels can cause settlement damage to buildings and infrastructure. We want to avoid that. That is why we monitor the groundwater as a safety and information measure. This provides us with real-time data should any changes occur underground, says Bonnafous.