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AWARD – Beaulieu Parkway Bridge, Chelmsford

Spanning a busy railway line and road, a 161m-long three-span weathering steel bridge eases congestion in and around a new housing development in Essex.

FACT FILE
Architect: AECOM
Structural engineer: AECOM
Steelwork contractor: Briton Fabricators Ltd
Main contractor: GRAHAM
Client: Countryside Zest LLP

Providing a link to a new housing development in Chelmsford, the Beaulieu Parkway Bridge is a vital piece of infrastructure that alleviates congestion and therefore delivers transportation benefits for the residents of the Essex town.

Constructed over an 18-month period, the bridge spans a main railway line and the northbound A12 slip road, as well as providing access to the planned Beaulieu railway station, which is scheduled to be completed in the next couple of years.

To minimise railway and road closures and the associated risks of working over transport assets, the project team developed a design concept to allow off-line construction of the bridge and its subsequent movement to the final location.

Curved on plan, the steelwork elements for the bridge consist of four lines of 2.7m-deep plate girders, which have been designed to twist into shape under permanent load.

“Accuracy of fabrication was controlled in the workshop, using laser levels and purpose-made jigs,” explains Briton Fabricators Managing Director Dean Morcom.

“Information was gleaned from our advanced steel 3D model, which was prepared in-house by one of our experienced design modellers.”

Overall, the steelwork contractor fabricated, supplied and erected 891t of weathering steel for the bridge.

One of the main challenges that had to be overcome was the confined nature of the site and the limited access. Consequently, the plate girders were delivered in small sections that were then welded together into 40m-lengths on site.

In order to carry out this preliminary work, temporary trestles, to support the girders, were designed and deployed, while shrouded areas were installed to allow the team to weld, test and blast the steel sections.

Once the paired girders, weighing up to 132t each, had been made up into the required lengths, they were then lifted above the adjacent overhead railway line structures and transferred onto another temporary works set up.

This ‘at height’ temporary location mimicked the bridge’s final abutment and its two intermediate central support piers. With two rows of purpose-built trestles positioned at weld locations, all of the structure’s connections were completed.

“Accuracy was once again paramount, at controlled temperature ranges, to ensure the 16 bearing positions were kept within tolerance,” added Mr Morcom.

“Once handed over to the Tier 1 contractor, they then set about constructing (in part) the bridge’s concrete deck and associated wing walls.”

Once all of the preliminary works had been completed, a number of self-propelled moveable transporters (SPMTs) lifted and moved the entire bridge superstructure to its permanent location. The bridge weighed 2,400t during the installation programme.

It was manoeuvred and cantilevered over the Great Eastern railway line and the A12 north bound slip road and installed within a 10mm tolerance. It is believed that this was the longest bridge installation ever undertaken in the UK using SPMTs.

Martin Leach, Managing Director, Major Projects, Countryside, says: “We were enormously proud to announce the opening of the new Beaulieu Parkway bridge and relief road for Chelmsford, the final stage of a £35M infrastructure programme which will have such a positive impact on the local community.

“The completion of the bridge is a fantastic moment for Chelmsford, facilitating the opening of the new relief road which provides a much more convenient link between the A12 and the A130. This will significantly reduce congestion from local roads in Springfield as well as provide easy access to the new Beaulieu Park station.

Councillor Lesley Wagland, OBE, Deputy to the Leader with principal accountabilities on Major Infrastructure Projects and Freeports, says: “I am very pleased the new Beaulieu Parkway bridge and relief road is now open to traffic. It is providing an important strategic link for commuters and is intended to help ease congestion around Springfield as people journey to and from Braintree, Stansted and the M11.

“Essex County Council has worked hard with partners to put in place a number of transport developments in this part of Chelmsford, from the relief road, to the new bypass and train station, which are vitally important for making sure the transport network is fit for the future and giving local people a safer, greener and healthier choices in how they travel.”

Summing up, the judges say this three-span highway bridge has an extraordinary construction story. The structure, which spans a road and live railway, is curved in plan and section. Built on the ground, complete with much of its deck, the structure was then driven into position on multiple SPMTs.

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