24/7 dynamic monitoring – total confidence and a UK first for Academy Geomatics Ltd
KOREC customer Academy Geomatics Ltd is combining data from a Trimble S7 Total Station and a range of Move Solutions geotechnical sensors, all in a single Trimble platform. This system will provide the live 24/7 monitoring data required to keep the train users and tunnels of Newcastle’s Metro safe during extensive above ground construction work.
Key benefits of the Academy Geomatics monitoring system on the Metro project
- Effective combining of total station and geospatial sensor data for total confidence
- Dynamic system – Live 24/7 system for fast reaction to any detected movement
- All data managed in a single platform, Trimble T4D, for easy analysis and reporting
- Proven fast support and back-up from the KOREC monitoring team
- Ability to customise all Move sensors on the cloud platform
- A UK first! Useful, cost-effective power system using a POE cable
Download a PDF of the case study here
This summer, building work officially started on a new £155m HMRC headquarters in Newcastle. The Pilgrim Quarter project will be the biggest office development in Newcastle city centre’s history and is located very close to the underground Metro tunnels in the area. Whilst construction is scheduled to run for 2 years, Nexus (who run the Metros) have requested that affected tunnels be monitored both during the project and for an additional year after completion.
Academy Geomatics Ltd, specialists in monitoring applications, were asked by Cundalls / Bowmer and Kirkland to propose a monitoring scheme for both the Metro running tunnel and the ventilation tunnel running alongside.
Before proposing a scheme, Academy Geomatics, under the guidance of Director, Mark Anderson, conducted an initial topographical survey in 2021 of the tunnels to relate their location to a previous survey at ground level. A control traverse was conducted between the two nearest stations which also linked up with two previous Academy surveys of the Metro stations. The lines of the tunnels were measured in outline until the area of interest was reached. The area was also laser scanned to provide the 3D information needed to produce the drawings, give a representation of the tunnels’ current condition and allow for the 3D design of the monitoring scheme. Trimble instruments were used for all these surveys, including the Trimble X7 3D Laser Scanner.
Site challenges and scheme proposal
The purpose of the scheme was to provide total confidence for Nexus that both the users of trains and the Metro tunnel itself were protected during the construction work.
Running tunnel: Having established that 155m of the running tunnel needed monitoring, an automated Trimble S7 Total Station system was chosen as the best option, along with a Trimble Settop M1 robust communications hub. When combined with Trimble 4D Control software (T4D), the Settop M1 enhances the operation of the Trimble total station combining the functionality of a field computer, device server, router and remote switch all into one device. This streamlines the number of components needed in the tunnel.
The tunnel length was divided up into 18 sections, which corresponded with an adjacent pile on the site. Five prisms were then placed around the cross section to establish if one side of the tunnel moved more than the other. Ninety-four prisms were used in total. Additionally, two Move Solutions accelerometers and one vibrometer were installed to produce dynamic monitoring results and an overall complete understanding of any deformation occurring in the tunnel.
Ventilation tunnel: The ventilation tunnel offered no lines of sight for an automated system and instead tilt sensors were deemed to be the most logical solution. The 28m long ventilation tunnel was divided into three cross sections and three tilt sensors per cross section were installed, nine in total. These sensors proved a useful choice for both their accuracy and low power wireless comms.
Each cross section would have varying influences from the construction site and the tilt sensors on either side of the tunnel would also experience different influences. It would therefore be easy to see any changes in deformation by work on the site.
An accelerometer sensor was also installed at either end of the tunnel and also a vibrometer to take advantage of the fault detection and diagnostics (FDD) and modal analysis functions within the Move Platform. These additions maximised the usefulness of the system by changing it from static monitoring to dynamic.
A UK first!
In the running tunnel, the distance from the best instrument position to the bottom of the vent shaft, where there was power available, was 40m. Not wanting to run large voltages of big cables down the running tunnel, with the help of Move, a bespoke Dyna-mo Instruments comms and power setup was established so that the instrument could be powered by a POE (Power over Ethernet) cable. The ability to deliver power and data with a single cable is a more cost-effective option than optical fibre and does not require a qualified electrician for installation. The use of a POE cable in an application of this type is thought to be a UK first!
A live camera feed from two cameras placed within the running tunnel provided security for the system. Additionally, if movement did occur, having eyes within the tunnel would be critical for Mark and his team.
Adept at installing monitoring systems, Mark reports that it took a week of night shifts to install, setup and configure the project. The Trimble S7 Total Station measures rounds to the ninety-four monitoring prisms every 30 minutes and the readings from the tilt sensors also come in every 30 minutes. With part of the ventilation tunnel being below the construction site, when the construction activities move closer, Academy will change the epochs to every 5 minutes to ensure there is no direct site activity affecting the tunnel.
The total station and tilt data is presented to the client using Trimble T4D. Various analysis charts are configured for the client and automated alarms and reporting have also been set to give maximum confidence that the site work is not affecting the running and ventilation tunnels.
The dynamic monitoring data is reviewed by Academy Geomatics staff on a daily basis, looking for trends, changes in trends etc.
Mark concludes that the system is up and working well, delivering the live 24/7 monitoring which he sees as key to the success of the project. He also reports that as well as being able to supply the data that provides his client with total confidence, he himself has been reassured that the KOREC monitoring team will always be there if he needs it by providing the support that’s vital for the smooth running of the project. In one instance, KOREC received a call at 5.00am at the start of a shift on Friday morning and was able to replace a cable by 5.00pm that night, all in time for the evening shift.
Following the successful installation of this scheme, Bowmer and Kirkland has since contracted Academy Geomatics Ltd to undertake façade monitoring with Move Tilt Sensors.
Academy Geomatics Ltd became a UK Technical Partner with Move Solutions this year.
KOREC is a UK distributor for both Trimble and a Move Solutions Partner.