Propping and monitoring ensures safety of key transport link

Kennington Bridge, Oxfordshire

Project Overview

Location	Kennington Bridge, Oxfordshire
Products	Mat 125 Insite real-time monitoring Hymat Jacks

Oxfordshire County Council identified the need to replace Kennington Bridge in 2019. As further design and planning work was required before construction could begin, the bridge needed to be carefully managed in the interim. Mabey Hire’s propping and monitoring systems have supported Milestone Infrastructure in maintaining the stability and safety of the structure during this period.

The challenge

Live structure with ongoing deterioration

The bridge was found to have deteriorating bearings and an increasing angle of inclination, which posed a potential long-term risk if left unsupported. Temporary propping needed to be installed carefully to stabilise the structure without causing further stress or movement. Mabey Hire designed and implemented a precise propping system that provided immediate support while accommodating the bridge’s existing condition.

Complex site conditions

Kennington Bridge spans four live railway lines, making access and installation of temporary works particularly challenging. All activity had to be coordinated closely with rail authorities to ensure safety and avoid disruption to services. Mabey Hire’s solution was engineered for efficient installation within tight working windows, minimising risk and downtime.

Integration with ongoing work

While plans were being developed to replace the bridge, the temporary works had to remain effective and adjustable over an extended period. This required careful monitoring and occasional re-energising of jacks to maintain stability as conditions evolved. Mabey Hire’s ongoing engineering support and monitoring systems ensured the bridge remained safe and serviceable throughout the planning phase.

Our solution

Chris Sadler, Principal Engineer at Milestone Infrastructure (now M Group Highways), explained: “Mabey Hire’s propping scheme was installed in between the in-situ columns, with seven props used to support the bridge deck. We used a mixture of Mabey Hire’s Mat 125 propping and Hymat hydraulic jacks, with its in-house design team drawing up a concept design based on our requirements.

“This design was then developed in AutoCAD and an analysis model in CADS A3D MAX for the anticipated load combinations. Due to the long-term nature of the equipment installation, each prop was designed to a 65 tonnes loading capacity, with Mabey Hire’s jacking experience integral to ensuring the equal load distribution of the bridge deck.”
Due to the structural concerns that had triggered the works and the fact that the bridge was remaining open to traffic throughout, it was essential that Milestone had continuous insight into the bridge’s condition and behaviour.

Chris explained: “As well as the propping and jacking scheme delivered by Mabey Hire, we also utilised their monitoring solutions and expertise. This provided us with invaluable insight, ensuring we had an understanding of how the structure was behaving, and gave us forewarning of future damage, should loads exceed pre-approved limits.”

Learn more about Insite real-time monitoring

To gain more information about the structure, we installed a range of our wireless monitoring sensors onsite, programmed to measure the bridge bearings in two axis, as well as tilt sensors to measure the change of movement on the pier crossheads and abutments. The entire system was installed by our site engineers over the course of planned rail possessions spanning multiple weeks. This was then connected to our unique web portal, with automatic alerts sent to key stakeholders at Milestone and Oxfordshire County Council should limits be breached.

Speaking about working with us, Chris said: “Mabey Hire have been really helpful throughout this whole process. Its live portal, in particular, is a great tool from an asset management perspective, ensuring that both the Council and ourselves are up to date with the bridge’s condition. We also receive monthly data reports from Mabey Hire’s monitoring team, which we use for benchmarking purposes and for presenting to other stakeholders.

Get in touch

“Mabey Hire are really easy to work with and the team have undergone multiple site visits to check on the equipment and its performance, as well as assist with other elements of the temporary works scheme (not delivered by themselves) in the early stages.”

Chris Sadler

Principal Engineer at Milestone Infrastructure (now M Group Highways)

Hymat Jacks

These aluminium hydraulic jacks are used extensively for bridge jacking and building refurbishments where stability and robustness is required to support high loads.

Learn more