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May 11, 2024

Innovative composite masts look to reduce cost and increase efficiency of rail electrification

Engineering consultancy Furrer+Frey will this week unveil its innovative composite masts for rail electrification, which could revolutionise the way that rail electrification is undertaken.

Engineering consultancy Furrer+Frey will this week unveil its innovative composite masts for rail electrification, which could revolutionise the way that rail electrification is undertaken.

Development of the mast brought together public transport electrification engineers Furrer+Frey with teams at Cranfield, Southampton and Newcastle Universities and composite materials manufacturer, Prodrive, as well as rail technology developers, TruckTrain. The project was part funded by the Department for Transport (DfT) and Innovate UK through the First Of A Kind competition. The first composite masts have been created and tested at St Bride’s feeder station, just outside Newport in Wales.

Whereas a traditional steel mast of the same size weighs around 750kg, the composite masts are around 80kg, yet have the same strength. The reduction in weight is a significant boost towards productivity and reducing cost.

Furrer+Frey GB head of UK projects Noel Dolphin tells NCE: “If you’ve got a well-designed mast that needs smaller, lighter plant that uses less fuel, it can be done quicker so you’re more efficient.”

However, this is just one factor. Dolphin explains: “The dead weight is just one small part of the load on a pile. It’s the weight, the wind on it, the weight of ice, the way the wires are hanging off – it’s a whole system. So we’ve designed a mast that’s not only lighter but has a lower wind resistance.”

This is significant because it means that the piles holding them in place can also be much shallower.

Having worked on the electrification of the Great Western Railway, Dolphin explains the significance: “The average pile foundation on Great Western ended up as 4.7m. So you’ve got the 6m tall mast and then you have to hammer a steel pile into the ground to hold that, which is about 5m underground. There’s a huge cost to sticking a 5m pile into the ground 11,000 times.” In areas with less secure ground conditions, the piles can be even deeper than 5m.

“The average on the Midland Mainline is 3.7m, so we’re headed in the right direction,” Dolphin says.

The piles for the prototype composite masts slash that by more than half, with piles only 1.25m deep – the shallowest electrification mast pile ever installed.

“If you’re install a pile that’s half the length you can do twice as many, and the price of the actual pile is less, so it’s making the whole system more efficient.”

It goes beyond the installation, though. The new piles will have sensors in them that report how much they’ve bent or sagged away from being vertical, so engineers will know when they need replacing. This is a far more efficient system then is currently in operation.

“We’ve recently worked on Thameside, which is C2C out of London to Southend and a lot of that route is marshy,” Dolphin says. “Every two years we’ve had to go out and measure every single structure’s lean, and there are 2300 structures on the section that we’re looking at. That means someone going up and measuring the angles and writing them up in a report. Yet you still get reports occasionally from a driver that a structure’s started to lean. Because of the marshy ground, about 50 structures a year are replaced on that route.

“Clearly, if you can have a structure that periodically reports back, you get a lot better information and you can see its history, but also someone’s not going out. So if you can embed low cost sensors in there, you can save on that.”

So far only a handful of the prototype masts have been made – and two of them have already been physically tested to destruction in a lab by pressing down on the cantilevers until they bend. This was to see if their actual resistance matched up with what had been calculated in the engineers’ finite element analysis models, which they did.

The demonstrator masts were hand-made by Prodrive, which is best known for working on Formula 1 cars. This is only for the prototypes, though.

“These two demos aren’t from a production line,” Dolphin says. “It’s all been off-the-shelf material, so we’ve had to search around the UK and then around the world. Some parts came from Finland, some from the US, just to get it done by march. It’s various fibre-reinforced polymers, and the stiffeners inside are carbon fibre.”

When they do take it to a mass manufacturing stage, it will be without carbon fibre inside, which presents another opportunity. “The other ultimate goal is that the structure is insulating in itself,” Dolphin says. “It’s another big saving if you can remove the insulators on the electrification cantilevers, as they’re expensive in themselves.”

Network Rail has maintained engagement throughout the project and will help work towards implementation on the network. “Network Rail definitely has a really strong interest in not only reducing rail electrification costs, but being very visible in reducing electrification costs,” Dolphin says. “They clearly want to show the DfT and the Treasury that they are working really hard on reducing costs.”

To that end, Ferrer+Frey and Network Rail have now jointly-funded a PhD in these masts, figuring out how to progress it. “We’re having someone focusing on how we optimise the structure for manufacturing,” Dolphin says.

He continues: “The next two years will be how do we optimise the design with a range of manufacturers to make it as affordable and cheap as possible. The final manufacturing structures will have the same properties, but have to be manufactured en masse at an affordable level.

“And then at the end of that, hopefully, it will actually be rolled out on real electrification projects.”

Expensive costs attached to previously delivered electrification schemes have rocked confidence in commissioning more schemes in the past. A Network Rail report from 2020 concluded that its industry partners must “demonstrate that electrification is both useful and affordable”, in order to convince government to fund more schemes.

Network Rail’s project report – drawn up in July 2020 and obtained by NCE via freedom of information request – concedes that there is a lack of public and government confidence in rail electrification projects due to “costly mistakes” on the Great Western scheme.

The electrified railway between Cardiff and London Paddington finally opened in January 2020, after years of delays and a substantial budget increase. The line was initially earmarked for completion in 2017, and included a budget of £874M, as determined in 2013. However the Great Western scheme was reset in January 2016, with the cost of electrifying the line rising to £2.8bn. Network Rail now puts the final cost as high as £5.5bn.

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