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Round-the-Clock: 24/7 Dynamic Monitoring Instills Confidence

Published Date

KOREC customer Academy Geomatics Ltd recently combined data from a Trimble® S7 total station and a range of geotechnical sensors into a single Trimble platform, Trimble 4D Control™. This system provides 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.

System Benefits:

  • Effective combination of total station and geospatial sensor data for total confidence
  • Dynamic, live 24/7 system for fast reaction to any detected movement
  • All data is managed in a single platform, Trimble 4D Control (T4D), for easy analysis and reporting
  • Proven fast support and backup from the KOREC monitoring team
  • Ability to customize all geotechnical sensors on the cloud platform

In the summer of 2022, building work officially began on a new £155m ($186M) HM Revenue & Customs (HMRC) headquarters in Newcastle, UK. The Pilgrim Quarter project is the biggest office development in Newcastle city center’s history and is located very close to the underground Metro tunnels in the area. While construction is scheduled to run for two years, Nexus (who run the Metros) have requested the affected tunnels be monitored both during the project and for an additional year after completion.

The specialists in monitoring applications at Academy Geomatics Ltd were asked by Cundalls / Bowmer and Kirkland to propose a monitoring scheme for both the Metro running tunnels.

Preparation

Before proposing a scheme, Academy Geomatics, under the guidance of director Mark Anderson, conducted an initial topographical survey in 2021 of the tunnel to relate its 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 line of the tunnel was 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 & 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.

Having established that 155m (509 ft) 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 T4D software, 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 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 accelerometers and one vibrometer were installed to produce dynamic monitoring results and an overall complete understanding of any deformation occurring in the tunnel.

Installation

Adept at installing monitoring systems, Mark reports 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 and readings from the tilt sensors 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 five minutes to ensure there is no direct site activity affecting the tunnel.  

The total station and tilt data is presented to the client using 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 tunnels. The dynamic monitoring data is reviewed by Academy Geomatics staff on a daily basis, looking for changes in trends and other indicators to inform action.

Mark concludes 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 the KOREC monitoring team will always be there if he needs it by providing the support vital to the smooth running of the project.  In one instance, KOREC received a call at 5:00 a.m. at the start of a shift on Friday morning and was able to replace a cable by 5:00 p.m. that night, all in time for the evening shift.

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