A fascinating time-lapse video marks a first for CSIC PhD student Mehdi Alhaddad who has successfully captured photogrammetric monitoring inside one of London’s busiest underground tunnels.
The video footage shows London Underground (LU) trains passing in the tunnel while CSIC technology monitors the tunnel lining for movements caused by the excavation and construction of a new Crossrail tunnel underneath.
The flashing beams of light and glimpses of CSIC’s instrumentation and personnel working deep underground are mesmerising, but it is the innovative monitoring system installed in the tunnel that is ground-breaking.
CSattAR monitoring system, developed by CSIC’s Mehdi Alhaddad, processes images captured at a specified frequency for the duration of the monitoring - the time-lapse footage is produced from the raw images.
This technology allows engineers to record extremely precise movements and monitor numerous points along the tunnel section resulting in additional valuable data for asset owners and managers. Engineers also have immediate access to the structure’s visual condition at a fraction of the cost compared to the conventional alternatives.
This deployment marks the first implementation of CSattAR inside a live tunnel and the monitoring technology secured valuable data for London Underground and Crossrail, verifying that there was no deformation to the tunnel lining despite the tunnel boring machine passing underneath.
“Initial results from the first-ever trial of photogrammetry to calculate tunnel induced movement within an operational environment are extremely promising and accurate. The added bonus of being able to visually observe any reaction has the potential to provide further confidence and understanding to asset owners,”said Mark Dewhirst, tunnelling engineer, Crossrail, at London Underground.
The success of this deployment has exciting implications, offering the infrastructure and construction industry new opportunities; asset owners and managers could use this innovative technology to monitor their assets in locations where it was not previously possible due to prohibitive costs and/or logistical challenges working within a live tunnel.
For many projects, a considerable amount of construction costs is spent on the required monitoring of assets affected by the new construction. Innovative monitoring systems, such as CSattAR, have the potential to reduce the costs of such monitoring and provide additional information which could enable more effective asset management.