The announcement of the new trains was made by Arriva UK Trains when it was confirmed that it would become the next operator of the Northern franchise from 1 April 2016.^[10] CAF were selected by Arriva as they were the only manufacturer able to produce both new diesel (Class 195) and electric multiple units from the same platform, the Civity, thus increasing familiarity for drivers and reducing maintenance costs once in operation.^[6] Bombardier submitted a bid to produce electric units based on their new Aventra platform, but was unable to offer the matching DMU that Arriva required.^[11] Furthermore, Bombardier already had a long order book for Aventra units and Arriva believed CAF were in a stronger position to guarantee on-time delivery of the units.^[11] At the time of placing the order, the £500 million value and 101-unit size made it CAF's largest-ever contract for a European customer.^[9]

Construction started in July 2017,^[12] with the first completed unit being unveiled on 31 January 2018.^[13] Testing began in the UK in September 2018,^[12][14] and in March 2019, a four-car Class 331 unit (331111) became the first train to be completed at CAF's Llanwern factory.^[15]

On 28 June 2019, the new trains were launched by a special service for the media. Regular passenger service with the Class 331 (along with its diesel counterpart, the Class 195) started on 1 July 2019.^[16]

Arriva UK Trains stated its aim for a "step-change in quality" for the new trains when compared with older trains in the Northern fleet such as the Pacers and Sprinters.^[10] The interior, layout and driver cab of the Class 331 (EMU) are identical to their sister units, the Class 195 (DMU) with the only difference being power generation and drivetrain.^[6]

The 331s have a 'doors-at-thirds' arrangement, and a top speed limited to 100 mph (161 km/h). The units have air conditioning, power sockets, one toilet per train, open gangways between individual carriages, passenger compartment CCTV, provision for wheelchair passengers and wi-fi system. All trains fitted with an automated audio information system, as well as display screens – six in each carriage ensuring all passengers have an unobstructed view to at least one. These screens convey a variety of information from station arrival times and informing alighting passengers when they need to be in a different carriage due to platforms being too short to accommodate the train.^[17]

Northern selected a "wide and spacious" vestibule area to allow for quicker passenger flows when boarding and disembarking to minimise dwell times which can result in delays.^[6] These large spaces around the doors offer a degree of flexibility as to how this space can be used with flip-down seats and standing space in times of overcrowding where the objective is ensuring more passengers can board. The units are not fitted with fixed luggage racks as these often reduce capacity on peak-time commuter trains – space is provided around the flip-down seats adjacent to the doors to store luggage and prams – thus not impacting on the capacity of the train or safety for passengers wishing to alight or board.

The Class 331 electric units are noted for their quick acceleration putting them among the fastest accelerating EMUs in the United Kingdom with a rate of 1.3 m/s² (2.9 mph/s).^[7] This allows the units to accelerate from 0 to 125 km/h (78 mph) in 45 seconds - by comparison, the ex-British Rail Class 321/322 units have an acceleration rate of 0.55 m/s² (1.2 mph/s) and which takes them over 2 minutes to attain the same speed.^[18][19] It is envisaged this improved acceleration result in efficiencies and improved punctuality on commuter routes with multiple stops across the Northern network.

The units are designed with a projected lifespan of 35 years and it is planned they will operate beyond 2050 with maintenance and refurbishment.^[6] Other features included are digital seat reservation system – however these are to future-proof the train and Northern do not envisage using these on many, if any routes. Although the vast majority of services will operate as three or four-car formations, some three-car units are doubled up to form six-car services. As a result, they are fitted with Automatic Selective Door Operation (ASDO) for use on routes where station platform lengths are not sufficient to fully accommodate the train. This ASDO is linked to an automated system which informs the passengers through both announcements and the passenger information screens located in each saloon.

In West Yorkshire, the Class 331 units replaced the eight Class 321 and Class 322 trains operating alongside the fleet of Class 333 units on Leeds/Bradford Forster Square to Ilkley/Skipton and Leeds to Doncaster stopping services.^[20] In the North West, the 331s were deployed on inter-city electrified services from Blackpool North to Manchester Airport and services from Hazel Grove to Blackpool North. The 331s were also introduced on the Liverpool Lime Street to Blackpool North route and the Liverpool Lime Street to Manchester Airport route.^[20]

Illustration edit

Named units edit

Both 331106 and 331110 are named Proud To Be Northern.^[21]

Units 331010 and 331109 also have a special NHS livery to thank them for their efforts during the Covid-19 pandemic.^[22]

• British Rail Class 196 - A diesel multiple unit variant of the CAF Civity UK platform built for West Midlands Trains.
• British Rail Class 197 - A diesel multiple unit variant of the CAF Civity UK platform being built for Transport for Wales Rail.
• British Rail Class 397 - An electric multiple unit variant of the CAF Civity UK platform built for TransPennine Express.