Two of Britain’s most progressive railway companies are challenging received wisdom on diesel passenger trains. Three years ago Chiltern Railways introduced former InterCity coaches to provide additional capacity on its route from London Marylebone to Birmingham Snow Hill and Kidderminster.
The antiquated slam doors were replaced with power doors. The coaches also feature LED internal lighting, power sockets for laptops and generous leg room. Although the coaches were designed in the 1970s, they equal newer trains mechanically and in crashworthiness. Most of the passengers probably assume they are riding in new trains, not relics from the era of the legendary BR sandwich.
Now the offer is improving again. The previous diesel locomotives, built in the 1990s for Royal Mail trains, have been replaced with six new Vossloh Class 68 locomotives, owned by Carlisle-based Direct Rail Services (DRS). Each Class 68 has a 2,800kW Caterpillar C175-16 engine feeding four AC motors – one for each axle. Each motor has its own inverter, enabling the loco to continue with 75% power if one set fails.
DRS is a subsidiary of the Nuclear Decommissioning Authority and its core business is transporting nuclear waste to Sellafield. Two years ago it piloted a train service for Sellafield workers, using refurbished 1960s coaches and diesel locos. Sellafield wanted to gauge the suitability of rail as an alternative for staff to commute. Gary Brownell, DRS’s senior business manager, says the trial was successful.
Later, the government came under pressure to reduce overcrowding on trains in northern England and to promise withdrawal of the unloved diesels known as Pacers. No new diesel trains featured in Britain’s rolling stock strategy, published last year, because electrification of additional routes was meant to ease the shortage of trains. However, the impact of delays to electrification schemes was compounded when Chiltern Railways agreed a lease from spring 2015 on several diesel trains hitherto leased by First TransPennine Express.
As the election approached, the looming shortage of diesel trains in northern England was pinning ministers into a corner. In January transport secretary Patrick McLoughlin announced that DRS would provide two loco-hauled trains for Northern Rail services on the Cumbrian coast from 17 May. The displaced diesel trains will plug gaps elsewhere.
Just a month before that announcement, Arriva Trains Wales had launched a refurbished loco-hauled train, at McLoughlin’s behest, to provide extra capacity between North Wales, Chester and Manchester.
Passenger trains hauled by diesel locomotives have popped up around Britain, from Scotland to East Anglia and Dorset. The motivation is usually to tide things over until newer diesel trains become available, but Chiltern Railways’ investment in upgrading coaches signals a longer-term commitment.
The fleet of 25 Class 68 locos also puts a new gloss on diesel haulage of passenger trains. DRS specified dual freight and passenger capability, despite having no firm interest from any passenger train operator when it placed the order.
Brownell says: “There was an element of speculation. A couple of key contracts were coming up that required loco haulage. The head-end power supply, or Electric Train Heating, was specified because we believed there was an opportunity out there.” Class 68’s fuel efficiency to date has exceeded DRS’s expectations, and there are tentative signs that the locos could be taken up for other passenger services.
“Some more recent franchise invitations to tender issued by the Department for Transport are looking for a return to InterCity-style service on the longer core routes,” observes Brownell. “A Chiltern-style push-pull set, worked by a Class 68 locomotive, could provide the desired service levels.”
Most non-electrified routes are operated by Diesel Multiple Units (DMUs), which consist of coaches with integral diesel engines and cabs at each end. Units can be coupled together. To reverse the direction of movement at the end of the journey, the driver walks to the cab at the other end of the train.
Obviating the process of shunting a locomotive to the other end of the train was one factor in the DMU becoming standard on shorter non-electrified routes in the 1950s and 1960s. British Rail overcame the shunting drawback by providing a locomotive at each end of the InterCity 125s, or by inserting a driver’s cab in the coach at the end of the formation for the loco to push the train in one direction (the ‘push-pull’ mentioned above). Time-division multiplexing gave the driver command over the loco at the rear of the train.
However, in the 1980s BR ordered many DMUs for longer routes. Two or three coaches per train usually sufficed.
Tilting at high speed
After rail privatisation in the 1990s, the DMU concept was taken a step further, with 160km/h and 200km/h designs. Virgin Trains specified tilt technology for some Voyager DMUs to permit higher speeds on curved track. However, fuel efficiency was not a strong point. Main-line speeds and acceleration dictated large underfloor engines, generating vibration and noise which affects passenger comfort.
Chiltern Railways went out of its way to give passengers on its longest route the comfort of non-powered coaches. For routes between Scotland’s seven principal cities, new ScotRail franchisee Abellio will upgrade InterCity 125s displaced by the Great Western electrification and Hitachi-built InterCity Express Programme (IEP) trains.
Electric and bi-mode IEP trains will displace hundreds more coaches, including those now hauled by electric locos on the east coast main line. First Great Western’s proposed order for a variant of bi-mode IEP to serve Devon and Cornwall would displace more coaches. If some of the coaches are updated to displace DMUs, DRS’s Class 68 locos could find employment on other routes.
The bi-mode IEP trains will have underfloor diesel engines, enabling them to operate over long distances after leaving electrified sections of track. The passenger saloons had to be reduced in height to accommodate the engines, and the trains will suffer a weight penalty from carrying the diesel engines and fuel on the electrified network. Some engineers argued for new diesel locos, to haul electric IEP sets on non-electrified track. The locos would have been redeployed when electrification made them redundant as IEP haulers.
Such flexibility is attractive to purchasers of new trains, as DRS has demonstrated with its order for Class 68 locos and for an electric variant, Class 88. Many components, including the monocoque, are common to both types. That gives DRS advantages in getting Class 88 – due to arrive in Britain early next year – through the approvals process.
“We don’t have electric locomotives currently,” says Brownell. “Having common things like traction motors and wheelsets will ensure our fitters are familiar with many aspects of the Class 88 locos from their experience with the Class 68.” Class 88 will feature a small diesel engine for use on non-electrified sidings or branch lines.
These locos are part of a larger European family, known as Eurolight. The monocoques have been reduced for Britain’s smaller loading gauge, but otherwise DRS has drawn on mainstream European technology and benefited from the type’s largely trouble-free introduction into British service.
Nobody can predict how far electrification will spread in the next 30 years. The current programme might end with the completion of schemes already announced, leaving many inter-urban routes with partial electrification. At the other end of the scale is a scenario where electrification costs have reduced as skills and techniques have improved, and justifying further electrification is easier as more people use trains and the greater proportion of tracks already wired leaves smaller and smaller gaps to be filled.
This should become clearer when the Great Western, Midland Main Line and TransPennine electrification schemes approach completion. Decisions on any new diesel trains are needed sooner.
The latest iteration of Britain’s rolling-stock strategy estimates that 350 to 500 coaches will be needed by 2022 for non-electrified services. It flags up concerns over future-proofing this large investment and suggests mitigation strategies, which include “building the trains as unpowered vehicles to be hauled or propelled by diesel, electric or bi-mode locos”.
Retired rolling stock engineer Ian Walmsley says BR worked out long ago that a loco and coaches is better value than a DMU for trains of more than five coaches. The rule of thumb still holds, with good non-powered coaches costing about £1 million each. “A good loco could cost as much as £4 million to £5 million, depending on quantity, so a six-car train costs £11 million. A DMU costs over £2 million per car, so a six-car costs £12 million, hence the answer is five or six to break even,” he says. “There is an advantage in all the difficult stuff being in one place so you need fewer spare vehicles.
“The diesel loco would have a good residual value in Europe – assuming it is a modern standard such as the Class 68 – so the lessor should assume a 35-year life, if they want the deal, and the stock remains good for electric haulage.”
Five or more coaches may be needed in future where three or four suffice today. Passenger numbers rose through the financial downturn after 2008, and Network Rail predicts substantial further growth.
History has a part to play in a country where so much was invested in DMUs while electrification was off the agenda. Timetables on some routes are built around trains splitting or combining at an intermediate station, to focus resources on the busiest sections of route. Loco-hauled trains cannot practically be split up or joined together while in service. In places, infrastructure maintenance may have been tailored to lightweight DMUs, with their total weight spread over eight or more axles, rather than routine use by diesel locos, carrying traction equipment on four or six axles.
Where would DMUs go after displacement by loco-hauled trains? Walmsley believes it would be easy to find new homes for the long-distance DMUs built by BR in the 1980s. The Voyager trains, used extensively by the CrossCountry franchise, are another matter.
“Voyagers are so expensive to operate, secondary lines will not want them, although their owners might cut their lease price to make them attractive,” he says.
The place to see new technology coming down the line
The biennial Railtex railway equipment exhibition takes place this month, with a strong focus on innovation. The exhibition and conference are spread over three days, from 12 to 14 May, at the NEC in Birmingham.
More than 400 exhibitors will be showing their products, with 9,000 visitors expected through the doors. Attached to the event are a series of presentations and seminars aimed at engineers. Network Rail chairman Richard Parry-Jones will open the show with a keynote address on industry trends and business opportunities, while on day two Terence Watson, UK president of Alstom and co-chairman of the Rail Supply Group, will speak about the supply chain. On day three, Tim Shoveller, managing director of the South West Trains-Network Rail Alliance, will discuss efforts to improve services through co-ordination of train operations and infrastructure management.
Engineers keen on attending Railtex can register online for free at www.railtex.co.uk, saving themselves £20 on the door.