Monitoring the track at Lambertseter station

Cautus Geo is monitoring the metro track at Lambertseter station, where OBOS is building housing. "It's all about safety for travellers and the trains," says Svein-Ole Sjøtun of Sporveien.

200 sensors are distributed over 150 metres of SAA directional hose and 3-axial tilt sensors. They monitor every slightest change on the track. This has been the case since December. Cautus Geo has also used a design with two or more simultaneous systems for automatic and continuous track monitoring on Oslo S and the Gardermoen railway.

In Lambertseter, OBOS is to build a combined commercial and residential building with 61 customised apartments for the elderly. Underneath the building, two basement floors are being excavated for a car park. This is taking place close to the station and the underground railway line. The contractor is Consto.

At Sporveien, Svein-Ole Sjøtun is responsible for track and railway technology. They have set clear requirements to ensure safety.

- The development is very close to the railway and the ground conditions are not the best. That's why monitoring was required. The metro must be safe and traffic must not be disturbed by construction activities," says Sjøtun.

The method chosen provides continuous monitoring of the track. Two different systems deliver data to a control centre with a temporal phase shift."Sporveien is not aware that this setup and this phase shift have been used elsewhere," says Sjøtun.

Showing social responsibility

- This is where Sporveien, OBOS and Consto take social responsibility. "Continuous monitoring before excavation of the site provides good background and reference data for establishing warning limits if something happens to the track during the work," says COO Atle Gerhardsen of Cautus Geo.

The aim is to ensure the safety of travellers, structures and infrastructure.

- "We work closely and well with Sporveien and the contractor Consto. For us, it's great to be involved in securing important infrastructure in an urban environment," says geologist Sigmund Brekke Langelid of Cautus Geo. He is the head of fieldwork at Cautus Geo and is central to the implementation of the monitoring.

There is a growing focus on continuous and automatic monitoring of commissioned tracks.

- That's why it's important to have tried and tested automatic metering systems that require little maintenance and work all year round," says Langelid.

New experience

OBOS has built a lot at Lambertseter and has around 5,000 homes there. Bølgelengden will now be built. It's a 12,300 square metre building, with 2,000 square metres of commercial space and the rest apartments. There will be a two-storey underground car park.

- Continuous and automatic monitoring with sensors will be a new experience for us. It will be established according to Sporveien's requirements. Cautus Geo's solution provides continuous control and helps Sporveien to drive past the construction site as usual," says HSE/KS manager Kjetil Rammen at Consto.

Demolition and site preparation started in December. Sheet piling and excavation have not started. The construction period is 22 months. This means that the building can be ready at the beginning of 2025. Residents will then have a pharmacy, shops and other services 100 metres from their front door in the building with commercial premises on the ground floor and parking in the basement.

Reports and alerts

Sporveien sets strict tolerance requirements for track evenness. Cautus Geo sets up the monitoring with the Cautus Web access solution. Data from the sensors is collected continuously. An alarm level is established to detect possible unevenness in the track. The rails should be as level as possible.

An alarm is triggered if tolerance requirements are exceeded. E-mails and text messages are then sent to Sporveien and the contractor.

- If the alarm goes off, Sporveien will carry out safety assessments and assess the need for measures," says Sjøtun.

He sees the monitoring as an advantage for the contractor as well.

- They are automatically alerted to any indications that something may be happening to the pit. This means they have to carry out checks and can take action at an early stage. This is a bonus for the contractor. Measures taken at an early stage are less disruptive and cost-driving in the construction work, in addition to increased safety for the workers on the construction site," says Sjøtun.

Instrumentation

• 150 metre long automatic SAA directional hose in track.
• 50 tilt sensors.
• Cautus Web for receiving, analysing, reporting and automatic notification.