With the delivery of the last Class 350/3 EMU to London Midland in August, last month’s The Rail Engineer focused on the 77-strong Class 350 EMU fleet based at Siemens’ Kings Heath Depot in Northampton. This month’s issue considers the introduction of the smaller fleet of ten Class 350/4 EMUs earlier this year on First TransPennine’s Manchester Airport to Glasgow and Edinburgh service.

These ten 350/4 units, together with the ten 350/3 units recently delivered to Northampton, were part of a £145 million order secured by Siemens in 2012 which also included a maintenance agreement and the electrification of their Ardwick depot. The first units to be delivered under this order were the Class 350/4 units which were received between November 2013 and March 2014.

Manchester to Scotland electrics

December 2013 saw the completion of phase one of the North West electrification project from Castlefield junction in Manchester to Newton Le Willows. This provided an electrified route from Manchester to the northern part of the West Coast main line (WCML) and was the spur for the early delivery of the Class 350/4 trains which could then provide an electric train service between Manchester and Scotland.

Class 390 Pendolinos also took advantage of this electrification for empty stock moves from the northern WCML to Longsight depot, such moves having previously been routed via Crewe.

The first Class 350/4 passenger service between Manchester and Scotland was on 30 December 2013. Thereafter these units progressively replaced the Class 185 Desiro DMUs until all were in service by 2 April 2014. On 26 April, a special train consisting of a Class 350/4 unit ran between Glasgow Central and Manchester Piccadilly in 2 hours 46 minutes, stopping only at Carlisle for a crew change. The current timetable has eight stops and takes 3 hours 17 minutes.

Class 350 reborn

When Siemens received their order for a further twenty Class 350 units from Angel Trains, it had been four years since the last one had been built. In that time, manufacturing techniques had been changed and new standards introduced. Furthermore, this new order incorporated modifications made to earlier units to enable them to run at 110mph. However, the Class 350/4 units currently remain restricted to 100mph pending certification by Network Rail for 110 mph running on the northern WCML.

The requirements for 110mph running included strengthened traction-motor rotors to enable them to run at 5,000 rpm, pantographs with open archorns that are both lighter and have improved aerodynamic properties, increasing lateral damping from 30kN/m to 50kN/m and modification to control software. In addition, the new units had GSM-R radio fitted, updated TPWS and AWS, and new CCTV and fire detection systems to meet new European interoperability requirements.

The Class 350 EMU comprises of four 20.3 metre-long aluminium coaches. At each end are driving motor coaches with a 250kW asynchronous traction motor on each axle, between these are a pantograph vehicle with the transformer and a trailer vehicle. The Class 350/4 unit weighs 170.4 tons. Its total power of 2 MW (2,700 hp) gives it a power-to-weight ratio of 15.7 hp per ton.

The Class 350/4 is configured for an inter-city service and so has a total of 197 seats, compared with the Class 350/3’s 230 seats. It has more luggage space and is the only Class 350 unit with 2+1 seating in first class.

Electrifying Ardwick

The £30 million Ardwick train maintenance facility was opened in February 2006 to
service and maintain the new fleet of 51 First TransPennine Express Class 185 Desiro DMUs. It includes a two-road fuelling point and a depot building with four roads that each accommodate four Class 185 units, each consisting of three 23-metre vehicles.

141023 133425 [online]

In July 2009 the Government announced the 51 km route between Manchester and Liverpool was to be electrified at a cost of £100 million. A few months later plans to electrify a further three routes in the North West were announced bringing the total cost of the North West electrification scheme to £400 million.

With this announcement it was clear that Ardwick could no longer be a diesel-only depot and so its conversion to accept electric units was part of the same contract to procure the Class 350/4 units to run over the newly electrified railway. This entailed electrifying most of the depot’s external tracks including cutting back the fuel road canopies and modifying the train-wash which had its roof-level brushes removed.

The depot was extended by ten metres to accommodate the lengthening of all four roads along with their pits and overhead cranes. Although only one road has been electrified for the Class 350/4 fleet, extending all four roads future-proofs the depot for additional EMUs that it may acquire on completion of the North West electrification scheme in 2016. On the electrified road, a high-level access system interlocked with isolation was provided and the diesel exhaust ducts were removed.

This work was undertaken by Spencer Rail at a cost of £5 million and was started in September 2012. The depot work was completed by July 2013 although a problem with OLE at the depot entrance curve meant that it could not receive electric trains until November. As a result, the first two Class 350/4 units to be received were commissioned from Arriva’s Crewe depot.

The depot now typically handles seventeen Class 185 units and six Class 350/4 units each night.


Maintaining EMUs at Ardwick created 20 new jobs, bringing the depot complement of technicians to around 60, all of whom work on both the Class 185 and 350/4 units. Training for this started in April 2013 with a small number of technicians sent to the Siemens facility at Wildenrath, Germany.

The training of existing staff took around one week per person and was done both at the Northampton Depot and in the training rooms at Ardwick. It helped that the Class 185 and 350/4 share the same bogies and much of the braking system and also have a similar train control system.

Keeping the fleet running

The Class 350/4 units typically make three Manchester to Scotland single trips each day and each travel 260,000 miles per year as a result. This is higher than the other Class 350 units which run services with more stops with some units not being used off-peak.

The availability requirement on this service is 80% from Tuesday to Thursday and 90% from Friday to Monday. This is a demanding requirement for this small fleet as a random event taking one unit out of service reduces availability by 10%.

The units receive an examination every 16,000 miles, alternating between A and B exams. The A exams are done overnight. The B exams take 24 hours and balance all the maintenance required over a two-year cycle. Other routine maintenance includes defect management and tyre turning on Ardwick depot’s wheel lathe.

The heavy maintenance requirement for the fleet is determined by the 750,000 mile bearing life of the traction motors. At this mileage, traction motors and bogies will be given a thorough overall.

Each night, about half the fleet remains in Scotland – split between Corkerhill and Craigentinny depots. Here the units are cleaned and serviced. The maintenance requirement is limited to compressor oil level check and external visual checks.

Initial experience

It might be thought that training the staff and modifying the depot should ensure a trouble-free service introduction. Well, not quite, as there is no substitute for experience and, as reliability engineers know, one end of the bathtub curve is the result of early ‘infant mortality’ failures which, to a degree, affect all new products.

One such infant mortality was the new Mark 4 TPWS control unit which resulted in units being taken out of service due to spurious fault light indications, found to be due to the self-test signal, generated at each green signal, not always being detected as the field from the test coil was too weak. Depot technical staff worked with Unipart to resolve this problem and the resulting modification has now been fitted to all units.

141023 132100b [online]

On one unit, the Buckholtz relay kept tripping due to air in the transformer oil. As this is a rare fault, Ardwick was unlucky to experience this on one of its fleet of ten units. It took some time to resolve this problem which required the use of gas recycling equipment from Northampton depot and oil samples being sent back to Siemens in Germany. This did, however, provide the depot staff valuable experience on this equipment.

Random events outside the depot’s control included a pantograph hitting an OLE dropper and body damage from a loose load on a freight train. Also an object on the track punctured a transformer oil pipe. These pipes have since been fitted with shields.

7,500 + 40

The addition of 40 vehicles to the UK’s current fleet of 7,500 EMU coaches might not be thought to be particularly newsworthy. However, as has been seen, the introduction of the ten- strong Class 350/4 fleet and its maintenance at a previously diesel-only depot was not straightforward. Doing something new on the rail network is rarely easy and Ardwick has risen to the challenge of adding electric trains to its diesel depot.

The Class 350/4 trains may be new but the newly electrified railway over which they run is certainly not. The Liverpool to Manchester railway was opened in 1830 and was the site of the Rainhill trials won by Robert Stephenson’s Rocket steam locomotive. It is the world’s oldest public railway still in operation and was built by Robert’s father George who, towards the end of his life, said that “one of the great uses to which electric force will be applied eventually will be the simple conveyance of power by means of wires”.

How right he was, even if it has taken 183 years for the Liverpool to Manchester line to get from Rocket to the Class 350/4.