South Yorkshire Passenger Transport Executive

One piece of track part of the way between Meadowhall South, in Sheffield, and Rotherham Central is unique. As a tram makes the journey, it slides onto the special section of track that connects it to the main rail network. There, it switches from driver controls to rail signalling, acting not like a tram but a train.

This fusion of light and heavy rail infrastructure is the UK's first tram-train – and if South Yorkshire's trial continues to be as popular in the second year as the first, we could see more hybrid services across the country.


Trams are ideal for inner-city public transport: they are above ground for easy access, have clear routes that can't be diverted like a bus, and most are electric powered for no emissions. But they aren't great for linking together our cities, which are further apart and tend to be connected by higher speed rail networks.

To get the best of both worlds, you have to cram them together into a hybrid known as the tram-train, a vehicle that can run on tram networks as well as standard heavy rail, despite their different power, communications, signalling and safety regulations. "The benefit is that if you already have a good tram network in your city and a relatively unbusy mainline railway network around the city, you can provide direct services from the suburbs to the city centre without building too much infrastructure," says Taku Fujiyama, a lecturer at University College London's faculty of engineering science.

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The tram-train trundling between Rochester and Sheffield city centre is the first of its kind in the UK, but the idea has long been used elsewhere, originating in the German city of Karlsruhe in 1992. (The UK does have trams that run on former train lines, but in those cases no standard train services operate as well, so they can continue to behave like trams throughout their journey.)

Britain's first tram-train started operating on October 2018 in South Yorkshire after a six year delay and quadrupling of costs to £75 million – largely down to unrealistic costings and more work required than expected, according to the National Audit Office – but now the first half of a two-year trial is complete.


And independent surveys suggest that despite the delay and spiraling cost, the tram-train has proven perfectly popular, with a 100 per cent user satisfaction score. (The research conducted by passenger group Transport Focus was taken immediately after the service's launch last year; a subsequent one is due in early 2020).

It's no wonder the project is popular. Aside from being a novel form of transport — who doesn't want to ride a tram-train? — the route links previously unconnected areas. Previously, residents of Rotherham could make the journey via a combination of train and tram, but a change was required to get into the centre of Sheffield, which is up a steep hill from the train station.

"Having entirely separate light rail and heavy rail networks that do not connect can mean that passengers have to change vehicles and absorb waiting times between destinations," says Fiona Ferbrache, a lecturer at the University of Oxford's Transport Studies Unit. "Tram-trains often provide new routes and connections, and can reduce the number of changes travellers have to make between different transport modes, which can help to create a more seamless journey."

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The South Yorkshire project was funded by the Department for Transport, with an eye to setting up tram-trains elsewhere, but the project is run by the South Yorkshire Passenger Transport Executive (SYPTE) and Stagecoach, the local tram operator, as well as National Rail and Network Rail on the, well, rail side.


So what are the tram-trains themselves? Seven Citylink Class 399 vehicles, made by Stadler, run on the line. They can run at speeds of up to 100km/hr – though don't travel at such top speeds on this route – are bi-directional, so no turning is required, and are kitted out with dual-systems for safety, comms and controls, so they work across both the tramways and the railways.

"There's specific kit that you wouldn't normally need on our trams… but we needed these vehicles to be dual-compatible between the tramway and the railway," says Tim Bilby, managing director of Stagecoach Supertram. "That's why these are a bit special."

How special? Bespoke wheels were designed that ensure the vehicle can operate on both tram and train lines. To be roadworthy on the tramway section, they require traffic indicators, horns, and rear-view cameras, but to work on mainline networks, they require what's known as a train protection and warning system (TPWS) as well as support for signalling.

The tram-trains must carry the radio communications used on the trams as well as the GSM-R system used in trains, and meet both network's differing safety requirements. Jose Carlos Redondo, technical project manager of the Project Citylink Sheffield for Stadler, says even the lights need dual systems. "When running a tram, you need [indicator] lights like a car," he explains — but it's confusing to run something that looks like a car down train tracks, so extra lights were added that can be flipped on to make it look like a train. Doubling up on systems to make the vehicle operate on both networks means the vehicles are more expensive than a standard train or tram vehicle.

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Alongside those unique requirements, the tram-trains have options when it comes to power. The ones in the trial have a dual power system thanks to a transformer on the roof, letting them use the different voltages needed by both trams and trains. However, the section of rail network that the tram-train runs on hasn't yet been electrified.

If Britain's rail network were fully electrified, it'd be easier and cheaper to roll out tram-trains, as less infrastructure work would be required. Installing overhead lines sounds simple, but it proved problematic, and was one reason for the delays. College Road Bridge, near Rotherham Central Station, was too low for the overhead wires, explains Bilby. "One of the options would have been what's known as a 'track lower', which is actually lowering the level of the track to create more room under the bridge," Bilby says. "However, as it is next to the river, it was a flood risk – it's been underwater this last week with the floods – so it has proven to be the right decision to instead raise the bridge."

The Stadler Citylink vehicles had another infrastructure issue: like many trams, they have a low floor for easier entry and exit for passengers. But Rotherham Central only had rail-style higher level platforms, meaning new ones needed to be built. "The platform heights are too high, so people would have to step down into the vehicle or up to get off it," Bilby explains. To solve the problem, the platform where the tram-train stops at Rotherham Central was extended, sloping down to a level that suits the lower-level vehicle.

While that sounds like a simple solution, it raised concerns that passengers would try to cross the tracks at that point, as it appeared similar to a level crossing. "There was a lot of work done looking at that and how to protect against that," Bilby says. One consideration was installing doors on the platform that only open when the train is there, similar to Jubilee line trains on the London Underground, but Bilby said there were concerns that the trial would be seen as a template for how all tram-trains should be run. "If what we did was set a precedent that you needed these secure doors, that starts adding cost into every system," he says, though it may seem odd to worry about such costs when the project's budget quadrupled. Instead of sliding doors, the station erected a barrier between the two tracks with plenty of signs.

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There was one other major piece of infrastructure required: the Tinsley chord, a 150m line of track that connects the tramway to the railway between Meadowhall South and Rotherham. The main concern there wasn't the track itself, but ensuring no trains could accidentally end up on the tram network – as freight trains are much heavier than passenger trams, a collision could prove deadly. "There's been a lot of work done to protect those vehicles, to make sure that only a tram-train vehicle can come off the railway onto the tramway," Bilby says. Axle counters ensure only the right vehicles can pass, while the tram-trains are tracked using magnets, so operators always know where the vehicles are on the network.

That's the vehicles themselves. There were other challenges, including training drivers, who need to be capable of driving both a tram and a train. All of the drivers on the project have at least a year of experience with the Sheffield Supertram. "The tram-train drivers were experienced tram drivers, but had to learn the rail route," Bilby explains. "It's not too long of a route, but the driver needed to be familiar with it and know where the signals were, and so on." Handily, says Redondo, the Stadler trains automatically switch between voltage and turn on and off systems such as signalling, helping the driver manage some of the work of managing two systems.

Plus, driving a tram is different than a train. Trams operate on line of sight; drivers operate to what they can see, such as traffic signals, pedestrians and cars. On the railway, the trains are signal controlled and drivers drive to the signals. "Our drivers needed to understand the rules of the railway, because when they transfer onto the railway, they're operating under those rules," Bilby says.

What's next? Alongside hoping to expand the route with another stop at Magna and perhaps on to the airport and Doncaster, the plan is to get more parking spaces at the tram-train terminus at Parkgate Retail Park, says a SYPTE spokesperson, with Bilby noting that the 31-car lot is limiting the number of riders. Bilby also says there are discussions to extend the timetable a bit later; it currently ends at 11pm, which is a bit early for Rotherham residents out in Sheffield of an evening. He'd also like to shift the timetable, as it currently runs at uneven times throughout the hour, to make way for rail traffic. "The service isn't evenly spaced around the clock face, which isn't the end of the world," Bilby says. "It's one of those things, we're not in control of it."

And that's one challenge that may hold back tram-trains: finding space on the rail network. "It's looking at what the options are, what the congestion is like on that route, what the availability of paths are, and whether it's electrified," Bilby says. That means tram trains simply may not be realistic everywhere. "So, for example, somebody may say that London should have a tram train (Purley or somewhere to Croydon City Centre), but unfortunately there is no spare capacity on the Brighton mainline," says Fujiyama, adding that the adoption of new signalling on mainlines, will hopefully create more capacity and precision with scheduling.

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These challenges are why Stalder's Redondo suggests including the rail network operator from the very beginning of any project. "This was causing a lot of delays in the project, from a planning perspective and economic perspective," he says. "We need to involve Network Rail from the beginning."

Beyond congestion, enthusiasm for tram-trains across the UK outside of South Yorkshire could also be held back by money. The quadrupaling of costs could put off potential projects, and there's not exactly a lot of funding going around of late. "Light rail was part of the UK Government’s Integrated Transport Policy and its 2000 Ten Year Transport Plan, however support and part funding for new light rail lines was withdrawn by 2004, which left light rail plans largely abandoned," notes Ferbrache. "Other countries have had more success in developing light rail schemes, partly because of funding strategies that make them less dependent on Government funding." Cities and regions having more power to fund transport projects will help encourage more tram-trains, predicts Fujiyama.

Despite those potential brakes – and the delays and costs in South Yorkshire – tram-trains are already spreading in the UK. Wales has signed contracts to run a similar project, and Manchester is investigating expanding its network via tram-trains. Bilby said representatives from Glasgow, Manchester and Wales have all come round for a visit to check out the tram-train. As expensive and delayed as it was, the South Yorkshire tram-train may be the first in the country, but it won't be the last.

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