Track transfer: This infrastructure hosted a heavy-rail service before Manchester Metrolink took over, enabling passengers to travel into the city’s central commercial area
When the German city of Karlsruhe launched its tram-train services in 1992, it wasn’t just the city’s residents who benefited. The local hospitality industry also did a good trade as officials, journalists and enthusiasts from Britain and other countries inspected the system, with a view to applying the principles or lobbying for tram-trains in their own areas. Back in Britain, the Department for Transport eventually agreed to explore the concept in 2008, announcing a trial from 2010 on a line north of Sheffield. But the trial never got off the ground and was replaced in May 2012 with a £58 million pilot that will see tram-trains operating on Sheffield’s Supertram system and using 150m of new track to access Network Rail metals, on which they will run into Rotherham. This will demonstrate the vehicles’ key attribute – the ability to share tracks with heavy rail trains as well as run along streets.
After still further slippage on the project, the pilot is at last due to begin in January 2017. The seven new tram-trains, which had already been ordered from Vossloh España, will enter service next year, confined to Supertram lines initially until the pilot starts the following year. They will be equipped to draw power from Supertram’s 750V DC overhead supply and Network Rail’s standard 25kV AC, although the pilot will use only the former.
Warrick Dent, Network Rail’s area director, says: “Tram-trains are a common sight in Europe, and we believe they could help to improve journey options for passengers around our towns and cities. We have had many complex issues to work through with our partners in the project to make sure that the vehicles can operate safely in Britain without causing disruption to regular tram and rail passengers.”
It has been reported that Network Rail has affected the rate of progress by scheduling infrastructure renewals to coincide with tram-train works. A spokesman for Network Rail says: “Project timescales have been revised to incorporate the comprehensive design works needed to adapt the rail network to allow tram-train vehicles to run. Efficiencies have been maximised by aligning the project with other investment programmes. The revised project timescale is also allowing improvement of the alignment of the route at Meadowhall, better using the existing tramway stop.”
On track in Tyne & Wear
In 2002, Tyne and Wear Metro light-rail vehicles began operating over 13km of Network Rail’s route between Gateshead and Sunderland, sharing the tracks with heavy rail trains. The Metro uses fully segregated rights of way, and its vehicles are not designed for on-street use. Light-rail vehicles are not designed to withstand the potential forces from contact with heavy rail trains. However, the heavy-rail network is equipped with the train protection and warning system (TPWS), which applies the brakes if drivers fail to respond correctly to visual trackside signals at high-risk locations. The Metro has an equivalent system, supplied by Indusi. All signals on the shared-running section of track are equipped with both systems, and trains not fitted with TPWS are barred from that section.
Travel plans: There are suggestions that tram-trains would be more appropriate for the Valley Lines in South Wales than heavy-rail electrification
The tram-train pilot will employ the same principles for shared track. TPWS will be fitted to all signals along the shared track, and additional GSM-R (global system for mobile communications – railway) equipment will be provided, says the Network Rail spokesman. GSM-R enables signalling control centres to contact drivers in their cabs.
This technology, combined with established safeguards such as interlocking of signals with points (track switches), will almost eliminate the possibility of collisions between vehicles. However, industry standards require tram-trains to show greater crashworthiness than conventional trams.
“The tram-train pilot aims to determine changes to standards required to allow inter-running of lightweight tram vehicles with heavy-rail passenger and freight traffic, and to gain an understanding of the changes to industry costs of operating a lighter weight vehicle, with track brakes, on the national rail network,” says the spokesman. Magnetic track brakes enable trams to replicate the performance of other road vehicles’ brakes when emergency stops are required.
The pilot will also scrutinise wheel profiles. Tram-trains require a profile which is compatible with tramway and heavy-rail track.
The vehicles must meet lighting requirements for visibility on Network Rail tracks, while headlights and direction indicators will comply with road traffic regulations. The pilot will include a safety campaign to educate passengers on using tram-trains on the heavy-rail network.
History makes the tram-train concept particularly potent in Britain. During the rail network’s formative decades, parliament took a back seat while private companies scrambled to build railways.
In many other European countries, government played a more hands-on role, resulting in central stations where routes converged, which provided a focal point for property development. By contrast, London and many other British cities received numerous stations, with the result that many of today’s railway stations are remote from the central business districts they aim to serve. The sole survivor of Swansea’s seven stations, for example, is a kilometre from the city’s modern heart.
Karlsruhe does have a similarly peripheral station. To close the gap, tram-train married existing tram tracks to suburban railways in 1992.
Manchester’s first Metrolink tram lines – also opened in 1992 – took over two heavy-rail lines into the city’s main stations. The new trams continued through the streets into the central business district. One of several subsequent additional Metrolink lines replaced heavy-rail passenger services between Rochdale and Manchester Victoria via Oldham, using new alignments to penetrate both town centres.
Greater Manchester’s remaining local heavy-rail services share sections of track with other trains. In 2013, Transport for Greater Manchester (TfGM) published a study which identified five routes for conversion to light-rail operation.
“Tram-train offers the prospect of extending the transport benefits of fast and frequent Metrolink service, with excellent city-centre access, onto the local rail network,” said the study. ‘While tram-train requires a substantial capital outlay, the ongoing costs are in most cases forecast to be exceeded by fares revenue. Therefore after the initial capital cost is incurred, tram-train services can be expected to be financially self-supporting, covering their operating and renewals costs.”
The study concluded that investing in tram-trains would create a future stream of transport benefits and public-sector cost savings. “This combination makes it a potentially attractive candidate for funding by central government.”
The pilot’s deferral is not expected to inhibit fundamentally TfGM’s own tram-train development, says a spokesman. One of the first requirements is a Transport and Works Act order for a new section of light-rail track to connect Metrolink and Network Rail metals.
Replacing Pacers
Setbacks to the planned cascade of heavy-rail trains have become a political hot potato in northern England, where many people had hoped to see the back of cheaply engineered Pacer trains as further route electrification released better diesel trains. Pacers and other old trains do not comply with European accessibility regulations, which will become mandatory in January 2020.
The tram-train pilot’s timeframe will not be shortened to compensate for the late start. Network Rail does not disclose how long an appraisal period will be required after the pilot, but it is clear that tram-trains will not be ordered in sufficient quantity in time to influence the number of vehicles that will require modifications for continued operation after December 2019.
Rolling-stock companies will expect to recover the costs from continued use of the modified vehicles. Could this undermine the business case for tram-trains? TfGM says: “Avoiding the cost of modifying Pacers was not explicitly allowed for in the business case for tram-train, and in any case it is unlikely that it could be implemented in Greater Manchester as early as 2019. However, this does raise the broader point regarding tram-train and its potential to influence future rail vehicle procurement proposals.”
Retired rolling-stock engineer Ian Walmsley believes the pilot’s delay does not have a significant effect on the financial calculations for tram-trains. He predicts that many Pacer units will have to continue in service beyond 2019.
Shared lines: Tyne and Wear light-rail vehicles use the same tracks as heavy-rail trains from the outskirts of Gateshead
Infrastructure alternatives
If tram-train had been tested several years earlier in Britain, different decisions on infrastructure investment might have been made. In 2009, the Scottish government cancelled the Glasgow Airport Rail Link project (heavy rail) on the grounds that it was unaffordable. Tram-train has subsequently been considered, and would cost less than half as much, but Transport Scotland says that results from the Sheffield pilot are needed first.
In Wales, the cost of electrifying the Valley Lines network – centred on Cardiff – for continued heavy-rail operation has been estimated at £500 million. Transport consultant John Davies believes that electrification for tram-train would be more appropriate. Although Cardiff has three stations that are close to shopping, employment and education sites, Davies argues that many residential areas and facilities in the city’s hinterland are remote from Valley Lines stations.
Tram-train would enable light-rail extensions into those areas, on-street or reusing derelict railway trackbeds. In many places, those trackbeds have been built over, but tram-train would obviate property acquisition and demolition by skirting around the blockages. Similarly, extending heavy-rail services to Cardiff Bay waterfront is impractical, not least because Network Rail has a presumption against creating new level crossings.
Walmsley believes that topography also bolsters the case for tram-trains in the Valleys, where the railways were built with steep gradients for transporting coal downhill to ports. Tram-trains would have a relatively high proportion of powered axles, providing rapid acceleration up the gradients and after the station stops, he says. In the opposite direction, tram-trains on the falling gradients would regenerate electricity by using the motors for braking.
Another potential advantage of tram-trains is that standard European vehicles can be used. Heavy-rail trains are bespoke for the British loading gauge – the cross-sectional dimensions determined by the profiles of bridges, tunnels and station architecture – and this increases production costs.
Walmsley cautions that even standardised trams are expensive. Older heavy-rail electric trains, cascaded from the London area, would be cheaper to lease than new tram-trains, but he argues that the additional expense of tram-trains could be covered by cost savings from the civil engineering required for light-rail electrification.
Cheaper electrification
Greater Manchester provides an interesting comparison between Network Rail’s North West electrification, which is suffering delays, and the Metrolink system’s recent expansion, where some lines opened early. Does this demonstrate that electrification for light-rail is simpler and more predictable?
TfGM thinks not. It attributes its recent successes to delivery by a consistent team over time. Carrying over experience and lessons learned “has resulted in efficiencies”, says the spokesman, adding that electrifying on-street track brings its own challenges, such as maintaining road-vehicle access for residents and locating support poles for overhead lines where footways are crowded with utilities’ apparatus.
Network Rail has to install electrification equipment without closing the affected railways for long periods. Constraints on access for engineers would also apply during electrification of heavy-rail routes for tram-train, other than in peripheral areas where trains can be replaced by buses for a year or more.
Network Rail also has to modify many bridges to provide clearance for new 25kV AC overhead line, and this requirement has proved more complex than expected in many instances. Light-rail 750V DC electrification can be less disruptive.
“Light-rail electrification will require fewer structures to be modified than for heavy-rail installation,” says TfGM. “This is a result of the reduced kinematic envelope of light-rail vehicles.”
Design can also be influenced by the speed at which vehicles will run, and by the chosen form of overhead line. “Where a proposed tram-train route has to accommodate vehicles from both systems, the 750V DC overhead electrification may require additional structures to be modified, to achieve clearance to the largest heavy-rail rolling stock,” it says.
The Metrolink light-rail fleet has consistent characteristics, whereas various train types use the lines involved in Network Rail’s North West electrification. “As a result, the scope of works such as re-signalling is less clear at the early stages and more challenging,” says TfGM.”