MR1594 – Bridge Monitoring, UK

Client
> J. Murphy & Sons

Sector/Market
> Infrastructure

Services
> Monitoring – Structural Health

Location
> Hackney, London, UK

Project summary

Network Rail appointed J. Murphy & Sons to carry out the removal and replacement of a failing railway bridge in Kingsbury Road, Hackney, London. Whilst the bridge had long been shut to traffic, it forms a key part of the city’s Cycle Highway and was frequently used, so replacement was essential.

The brief

J. Murphy & Sons, a company highly experienced in rail works, instructed Murphy Geospatial to undertake structural monitoring works of the bridge to mitigate any risks prior its removal and replacement.

The challenges

Due to the worksite consisting of two separate railway lines, there were considerable issues regarding access to site, with a single day possession taking over nine months for the client to acquire. This meant that Murphy Geospatial had a very short window of access and had to ensure all necessary works were carried out within the available shift. Having not been able to access the site prior to the installation, the team looked at various options for both installation methods and equipment to account for every eventuality once access was available, whilst also being suitable to install in the limited timeframe.

Our work

A total of 38 magnetic monitoring targets were installed on the underside of the bridge along with nine control targets away from the bridge outside of the zone of interest. An Automated Total Station (ATS) powered by solar panels was installed on a fixed post in a place of safety away from the bridge. The ATS measures the three-dimensional absolute displacement of the targets on site. Before each monitoring cycle the total station’s position and orientation were determined by a free station, which is calculated by the least square adjustment method.

As well as the prisms, eight tri-axial tilt nodes were also installed on the bridge underside to provide a secondary form of checking and recording bridge movement. These nodes work off a wireless flatmesh system, connecting to a nearby gateway and solar panel to provide constant data to an online portal.

Our team

Our monitoring team consisted of a project engineer to prep and supervise the installation works, a monitoring engineer to install the system and set up the network, and a survey team to carry out the installation and survey of the control network. A designated project manager was assigned to ensure the automated monitoring system ran smoothly and that the client and Network Rail were constantly informed on the monitoring results.

Results

All systems were installed and running within the allocated shifts required to get everything setup. The system remained in place for the duration of J. Murphy & Sons works prior to the bridge being replaced.

The observation data was viewed via an online portal and summarised in a weekly report. This enables the client and Network Rail to take immediate action if a trigger was breached or a critical event occurred.

The success of this project underlines our reputation in delivering services to equip our clients with the data and information they need to make decisions at every stage. We draw on the experience and skills of our people to deliver certainty our clients can trust.

Contact

For more information on this project, please email info@murphygs.com or call us on +44 (0)192 362 4800