The East West Rail Alliance received high praise at the prestigious Rail Business Awards 2022, having been recognised for the successful dismantling and rebuild of Bletchley Flyover, whilst putting the passenger first.
The Alliance was highly commended in the Infrastructure Project Excellence award, which recognises the most successful infrastructure enhancement or station development projects, across the UK.
The East West Rail project is currently working to connect Oxford to Cambridge, and is being delivered in three Connection Stages. The East West Rail Alliance, comprising Atkins, Laing O’Rourke, Network Rail and VolkerRail, is currently delivering phase two of Connection Stage One – connecting Bicester to Bletchley.
Opened in 1959, to allow passenger and freight trains travelling from East to West to cross over the West Coast Mainline (WCML), Bletchley Flyover was closed to passenger trains in 1968 and decommissioned for freight in 1993. As part of the East West Rail project, the structure has now been rebuilt to modern standards, to last 120 years, with minimal future maintenance.
As the longest of the 41 structures on the 37km Bicester to Bletchley route, this 605m flyover is the most complex structure to reinstate on the project, not least as it crosses the WCML, one of the busiest mixed traffic routes in Europe.
A partial rebuild option, rather than a refurbishment, was found to be the safest and most efficient solution; this option required fewer disruptive possessions, enabling the WCML to remain operational and minimising passenger disruption.
The Alliance team developed an innovative design and build solution, with a collaborative 20-month programme to:
With the combined weight of the spans being more than 2,800 tonnes alone, three of Europe's largest mobile cranes were used to dismantle the existing elements of the flyover before the rebuild process could begin. Once underway, the rebuild culminated in the installation of 103 40 tonne precast concrete beams, required to construct the new box bridge over the WCML during a single 72-hour possession over the Early May Bank Holiday in 2021.
Innovative precast shell abutments - 2m high and 1.75m deep - were used to design and build the new box bridge over the WCML, forming a 2m horizontal grid that could be stacked to create the required height, and then filled with reinforced concrete on site.
In total, 138 shell abutments were used to build the new 90m box bridge support structure across the WCML. Although shell abutments have been used on the railway previously, this was the largest and the first time they have been installed in such close proximity to an operational railway, proving that cranes can be used to lift significant infrastructure safely, without impacting services and disrupting passengers.
Mark Cuzner, East West Rail Alliance project director, said: “Designed and delivered within 20 months, on time and under budget, despite the complexity and added challenge presented by Covid-19, Bletchley Flyover is an example of what can be achieved to minimise passenger disruption and deliver industry-wide benefits when embracing collaboration, innovation and new ways of working.
“This recognition is testament to the hard work, dedication, innovative thinking and excellent engineering that everyone in the Alliance, our supply chain partners and our colleagues operating the West Coast Main Line has put in to ensure this critical element of the East West Rail project could be delivered safely and successfully.”
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