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First order in for revolutionary modular railway footbridge

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First published 1st June 2022, by New Civil Engineer. 

It’s official: the railway footbridge revolution has begun.

Greater Anglia has become the first customer to order one of the modular Ava footbridges, which will replace the old concrete pedestrian crossing at Stowmarket station in Suffolk.

The Ava footbridge was developed by a consortium including Expedition Engineering, Walker Construction, X-Treme Systems and Hawkins/Brown as part of the Transport Infrastructure Efficiency Strategy (Ties) Living Lab programme. The £5.4M initiative was funded by Innovate UK and Network Rail and, being cheaper and quicker to construct, it has the potential to disrupt the way rail infrastructure is delivered.

Rather than being built in a steel fabrication yard from standard sections, then shipped elsewhere to be painted before being transported to site as a full span length, the Ava bridge is designed to be assembled in 1.2m long modules using structural elements cut from flat sheets of stainless steel and bolted together.

The truss modules can be configured to suit the destination site, taking up as little land as is feasible. It’s fitted out with cladding, canopy, lighting and other mechanical and electrical services before being erected as close to finished as possible.

A demonstrator bridge is under construction at Widmerpool in Nottinghamshire but, even without having seen it, Greater Anglia was keen to get involved with the project and be the first to purchase one for use on the UK’s railway.

Greater Anglia asset management team programme manager Marek Dowejko told NCE: “The timing was perfect, because we just got funding for the Access For All scheme at Stowmarket. We did feasibility for the traditional construction, but then we pitched to Network Rail and the DfT to ask if we could use the remaining funds to do a second feasibility comparison. We proved that the funding required is less than a traditional build, it costs less and requires less maintenance. And we got the green light.”

Expedition associate director Eva MacNamara told NCE: “The demonstrator is in progress at the moment – we’re in the manufacturing and construction phase – so I think that’s what’s even bigger good news is that the confidence around the project is such that someone’s made an order before we’ve even completed the demonstrator. That’s absolutely brilliant for confidence in the investment that the Department for Transport (DfT), Network Rail and Innovate UK have made in this.

“I think that Greater Anglia see the potential of the savings that they can make with this project, so they’re willing to do that now rather than wait. One of the key things about this rollout and maximizing the benefit of that investment that that DfT, Network Rail and Innovate UK have made is the region’s understanding that it’s been de-risked by the prototype being in place. And, when they see that Stowmarket has already taken it up, we’re hoping that that will mean the floodgates open in terms of orders, which would be great.”

Walker will be carrying out the installation of the prototype bridge at Widmerpool in August this year and the new bridge at Stowmarket will be constructed in September or October of 2023. While the eventual aim is to be able to erect it within one possession – a matter of a weekend – on this first outing the engineers have backup possessions in case the learning curve for constructing it is steeper than anticipated.

Both versions of the bridge will have Ava’s “plug and play” lifts for accessibility purposes. These lifts are also usable on other Network Rail bridges, MacNamara explains: “That’s part of the innovation that we had here. The plug and play lift is separate to the stability system of the main bridge, we did that very deliberately. So, this could be a product on its own that would benefit Access For All for Network Rail elsewhere; imagine it being retrofitted to an existing footbridge, or they’ve got other footbridges in the pipeline where they could make use of what we’ve come up with.”

While they are not yet prepared to say how much the Ava bridge costs, they will say that it is significantly cheaper. “We think we’re around a third lower than benchmarks,” MacNamara says. “When we did the Stowmarket version, they thought that they couldn’t afford a bridge, but then when we showed them what we could do, they could afford a bridge. So this option made it possible for them to be able to afford this new bridge rather than a plaster job on their existing footbridge there.”

It should also get cheaper if bigger orders come in. “Until we get the economies of scale aspect of things where it’s procured in groups of five or 10, the best version of Ava savings won’t be realised,” MacNamara says. “That’s a challenge to the DfT – that they allow procurement that way. As I understand it, currently, bridges are procured individually. So that’s a challenge of what we’re trying to disrupt here, innovatively.”

She adds: “A really big point of this is that this is UK innovation that investment has been made in. We are looking for productivity benefits across the construction industry and in infrastructure, and here is something that is proven to do it. Roll up and make these economies of scale really work. Because, again, all of these benefits just get better and better.”

Revisit our in-depth feature on the development and benefits of the Ava footbridge.

Link to article on New Civil Engineer, click here.