Sensor tech raises safety standards, cuts costs and delays

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Fibre optic sensing methods developed by researchers at the EPSRC-supported Cambridge Centre for Smart Infrastructure and Construction (CSIC) are being used on a major London Underground line extension project, improving safety levels and reducing costs.

  • Distributed fibre optic sensing technology used to test the integrity of construction piles and walls both during and after construction
  • Cementation Skanska’s adoption of the system wins industry award, with safety benefits cited
  • Approach can improve quality, reduce overall costs and benefit structures throughout their lifespan

The system, which is being used by specialist piling and ground engineering subcontractor, Cementation Skanska, to extend the London Underground’s Northern Line from Kennington to Battersea Power Station, evolved from a project that began at CSIC in 2014.

Low-cost fibre optic cables are installed in diaphragm walls or piles to record temperature and/or strain distribution, and help to assess the integrity of structures.

The fibre itself acts as the sensor, allowing measurements to be taken at close spatial and time intervals along the length of the pile or wall. With this system the structure is monitored remotely, improving safety by removing the need for workers to manually check sensors.

In addition to the safety benefits it offers, the approach reduces costs by improving productivity on site, reducing material quantities and allowing for the early identification of anomalies so they can be effectively managed.

In some cases, the longevity of the sensors also means they can be used to monitor the structures over their entire lifetime, through to decommissioning. The system has multiple applications across a variety of different structures, such as bridges, concrete elements and retaining walls, and has already been applied in other projects.

As part of the collaboration between CSIC and Cementation Skanska, training was provided and software developed which has allowed the company to reach commercial readiness with a new specialist service, CemOptics, that is now being employed at other sites across its portfolio.

Cementation Skanska’s use of the technology led to the company winning the Editor’s Award at the 2016 Ground Engineering Awards, with the judges particularly impressed by the safety benefits delivered through the use of CemOptics.

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Since the centre was founded in 2011, researchers at CSIC have developed new technologies and methodologies to transform the way we design, build, operate and maintain infrastructure by enabling smarter, proactive decision making.

Methods pioneered at CSIC are already having an impact on major projects such as underground station upgrades and high-rise building construction, and the approaches used to monitor underground tunnels, energy and water infrastructure and railway lines and respond efficiently when problems occur.

In collaboration with a wide range of partners, CSIC researchers provide assistance and consultancy and, when requested, training on various monitoring technology options to members of staff at contractor and industry partner organisations on how to prepare, operate and monitor new systems.

CSIC is currently involved in more than 30 projects, one of which has seen researchers work with Network Rail to help them find better ways of monitoring and assessing problematic bridges among the estimated 18,000 masonry arch bridges that make up 47 per cent of the bridges they manage in the UK.

A sensing system has been deployed at an operational Victorian viaduct in Leeds that is able to detect even minor changes in the structure and show how it deforms over time.

By providing more accurate, up-to-date information on the condition of railway bridges, the monitoring could help Network Rail ensure safety, avoid unnecessary interventions and speed restrictions, and optimise repair work.

Distributed fibre optic sensors deployed by CSIC are also being used to generate information that no other monitoring system can provide during the construction of the 50-storey Principal Tower in London.

The fibre optic sensor cables embedded in the building’s concrete columns and walls provide crucial information on the shortening of the building during construction, which is used to guide the setting of floor levels. Eventually the embedded sensors could also be used to assess the structure during its lifetime.