Mabey and Ekspan deliver award-winning Bromley Heath Viaduct refurbishment
Leading bridge and engineering specialist Mabey has provided an innovative propping system to the South Gloucestershire Council to ensure essential work on the 50-year old southern Bromley Heath Viaduct could take place, despite extremely challenging project conditions. To meet specific project requirements, and to prevent damage to the bridge deck caused by excessive bridge beam displacement, Mabey also harnessed its real-time monitoring system.
Situated on the busy A4174 ring road, the Bromley Heath Viaduct, a 105-metre, five-span structure carries approximately 55,000 vehicles and 500 cyclists a day. Essential improvement works – including replacing the existing bearings – were necessary to manage structural deterioration.
The task was complicated by the South Gloucestershire Council’s requirements that, to avoid structural damage, the 16 bridge beams (comprising the deck) were lifted simultaneously, with a maximum displacement tolerance of 0.5mm between adjacent beams. Rough and uneven ground conditions also made the works more challenging.
In the early stages of project planning, Mabey’s team were approached by Ekspan, specialists in mechanical and structural movement control, to design a bridge propping and jacking solution that could facilitate this maintenance work and offer the necessary structural support and clearance.
Mabey implemented its Mass-50 propping system to support the 16 bridge beams while the permanent refurbishment activities were being undertaken. To ensure the displacement between two adjacent beams did not exceed the maximum tolerance permitted (both during jacking and refurbishment), Mabey also used a monitoring system with tilt sensors to record the project’s data in real time. The system triggers alarm warnings (via text message) should movement exceed the maximum levels permitted, meaning all parties could keep track of how the structure was performing.
Commenting on the project, Spencer Goff, Project Manager at Ekspan said: “Mabey’s innovative Mass 50 propping system allowed us to carry out bearing replacement on the viaduct work on the viaduct safely and efficiently, and in turn, helped us to minimise disruption for commuters using the A4174 Bristol ring road. The use of real-time displacement monitoring was especially valuable, enabling us to keep track of any shifts in movement and rest assured that the Council’s requirements were being fulfilled”.
The success of this renovation project, and its importance for the county of Gloucestershire, was recognised by the South Western Branch of the Institute of Highway Engineers, who named the Bromley Heath Viaduct it’s 2018 “Large Project of the Year”.
Gordon Macdonald, CEO of Mabey Hire UK, added: “Early contractual involvement meant we were able to collaborate with Ekspan from the off to develop a temporary works solution which would combine our expertise in propping and monitoring and ultimately deliver the viaduct improvements as quickly, safely and efficiently as possible. Receiving the “Large Project of the Year” award is a true testament to Ekspan’s clear brief and flexible working nature.”
After a year of refurbishment, the Bromley Heath viaduct is now open to the public.