Automated Track Monitoring for Murphy Group, Norfolk

Project summary:

This case study covers several projects attended by Murphy Geospatial to undertake automated track monitoring at the following locations for the reasons outlined:

Flordon Cutting: A section of the embankment had been noted to be undergoing some movement. Monitoring was required while the embankment was stabilised.
Thorrington Culvert: A culvert had undergone a collapse and had to be reinstated. Monitoring was needed for the track above while the works took place.
Lushington Avenue: A section of the embankment had been noted to be undergoing some movement. Monitoring was required while the embankment was stabilised.

The brief:

Mobilise immediately to site and set up an automated monitoring system to monitor the sections of track within the affected areas. The systems consisted of the following components:

Automated total station (Leica TM50 or equivalent).
ComBox with backup battery for control of ATS and transmitting data to servers for visual analysis and alarming.
1.5m mast with security cage and bespoke tribrach locks.
Monitoring glass targets for attaching to the web of the rails.
Monitoring glass targets for reference and control.

Three of these systems at the above locations were installed during an emergency shift attended by the monitoring team.

The challenges:

Murphy Group called upon Murphy Geospatial to attend the sites with very little notice due to the emergency nature of the projects. Murphy Geospatial responded within 24 hours by standing down teams to prepare for the impending night shift work in Norfolk. Equipment had to be prepared the moment the call came through at our London office and was ready to be collected by the teams for deployment on-site.

Our work:

Glass monitoring targets were installed in the rail web on identified structures to minimise track access requirements. A total of 54 points were established, with 46 monitoring prisms attached to the web of the rails and an additional 4 nearby OGLE columns. An Automated Total Station (ATS) was installed on a fixed post. The ATS measures the three-dimensional absolute displacement of the targets on-site. The final set of baseline readings was taken 7 days prior to any work commencing. Before each monitoring cycle, the total station’s position and orientation are determined by a free station, which is calculated by the least square adjustment method, with a minimum for four surveyed controls.

Our team:

Our monitoring team consisted of a project engineer to supervise the installation works, a monitoring engineer to install the system and set up the network, and a survey team to measure the geometry of the track. Our project manager also attended to speak with the client to ensure everything ran smoothly on the night and that the system was ready for reporting the following day.

Results:

All systems were installed and running within the allocated shifts required to get everything set up. The system remained in place for the duration of Murphy Group’s stabilisation works which lasted approximately 12 weeks for each site.