| owner = Porterbrook
| operator =
| depots = Neville Hill (Leeds)|(one per vehicle)
| enginetype = Inline-6 4-stroke turbo-diesel
| displacement =
The British Rail Class 144 Pacer is a retired class of diesel multiple unit (DMU) passenger trains built at Derby between 1986 and 1987. British Rail, seeking to procure improved derivatives of the earlier Class 141, placed an order with the manufacturers British Rail Engineering Limited (BREL) and Walter Alexander to construct their own variant, the Class 144. A total of 23 units were constructed. While formulating its long-term strategy for this sector of its operations, BR planners recognised that there would be considerable costs incurred by undertaking refurbishment programmes necessary for the continued use of these aging multiple units, particularly due to the necessity of handling and removing hazardous materials such as asbestos. In light of the high costs involved in retention, planners examined the prospects for the development and introduction of a new generation of DMUs to succeed the first generation.
In the concept stage, two separate approaches were devised, one involving a so-called railbus that prioritised the minimisation of both initial (procurement) and ongoing (maintenance & operational) costs, while the second was a more substantial DMU that could deliver superior performance than the existing fleet, particularly when it came to long-distance services. This prototype was introduced with much fanfare during June 1981.
The Class 144 units are equipped with BSI couplers. This allows them to work in multiple with Classes , , , , , , , , and units, as well as units of the same class. Post-refurbishment, the units emerging in a new silver and red Metro livery complete with refurbished interior. In December 2004, the fleet was transferred to the then-new Northern rail franchise. Northern Rail replaced the silver and red Metro livery with Northern Purple and Blue. By April 2010, all Class 144s had been repainted into this new livery.
Around 2010, Northern Rail subjected their fleet of Class 144s to another refurbishment programme. The first unit to be refurbished was 144006; it had also the first one to be refurbished in the joint Arriva Trains Northern/WYPTE Metro programme in 2002. The refurbishment enhancements involved numerous interior changes, including the installation of 'easy to mop' flooring, an extended area for bike storage at one end of the car by removing a bulkhead wall and extending the perch seats from three to four, repainted hand grips and stanchions, new dado side panels and repainted wall ends, retrimmed seats in the purple Northern Rail moquette, a repainted ceiling, and repainted driving cab.
During April 2016, Northern Rail's Class 144s were all transferred to the new franchisee Arriva Rail North; in turn, Northern Trains took over operations of the fleet on 1 March 2020.
Rail Vehicle Accessibility (Interoperable Rail System) Regulations 2008 and the subsequent Persons of Reduced Mobility - Technical Specification for Interoperability (PRM-TSI) require that all public passenger trains must be accessible by 1 January 2020. As originally delivered, the Class 144 does not meets this requirement and has to be withdrawn without modifications to become compliant. During the 2010s, the rolling stock leasing company Porterbrook proposed an extensive refurbishment of the Class 143 and Class 144 fleets with the purpose of satisfying the diverse needs of this requirement; it was noted that the envisioned modifications would necessitate a significant reduction in the number of seats available. However, due to the late delivery of the new trains, the 144s were to remain in service in the South Yorkshire area until the middle of 2020. Northern accordingly sought and received a dispensation allowing continued use until 31 August 2020, on certain specified routes only.
Withdrawal
thumb|Two ex-Northern Rail Class 144s stored at [[Bedale railway station|Bedale on the Wensleydale Railway, prior to being preserved]]
Following the outbreak of COVID-19 in the UK in March 2020 and the resulting curtailment of passenger services, Northern withdrew the entire fleet prematurely and, by mid-April, had placed all 23 units in storage; 18 units at the Keighley and Worth Valley Railway and the remaining five at Heaton Traction Maintenance Depot in Newcastle-upon-Tyne. Three units were subsequently scrapped, while the other 20 were distributed to preservation groups and other non-railway users.
Class 144e
The Class 144 Evolution (or 144e) proposal was publicised by fleet owner Porterbrook in 2015, as a way of bringing the fleet into compliance with the PRM-TSI requirements and thus extending its life past the compliance deadline at the end of 2019. One unit, number 144012, was refurbished to the Evolution standard and displayed as a proof-of-concept of upgrades including:
thumb|Class 144e unit
- installation of a universally-accessible toilet
- provision of two wheelchair spaces
- provision of a luggage rack and space for two bicycles,
- installation of new Fainsa seats
- installation of passenger wi-fi
- installation of passenger information displays and automatic voice announcements,thumb|Class 144e saloon
- installation of CCTV in the saloon, along with forward-facing cameras in the cabs, and,
- conversion of internal lighting from fluorescent to LED.
Porterbrook stated that it had paid £800,000 to prepare the demonstrator unit, but claimed that a price of £175,000 per train carriage, totalling £350,000 per two-car train or £525,000 per three-car train, could be achieved in volume production. It was planned that the demonstrator would enter public service in April 2015, but this was delayed until later in the year.
Fleet details
A total of 23 Class 144 units were built. The first thirteen of the class (nos. 144001 to 144013) are two-car units, while the remaining ten (nos. 144014 to 144023) have a third vehicle that was added later in 1987.
|-
|rowspan=2 |Preserved
|align=center |8
|144003, 144004–144007, 144009, 144011, 144013
|-
|align=center |8
|align=center |3
|144014, 144016–144019, 144020, 144022–144023
Preservation
Fourteen Class 144 units have been preserved in operational condition.
Operational
{| class="wikitable"
!rowspan=2 |Unit
!colspan=3 |Vehicle numbers
!rowspan=2 |Livery
!rowspan=2 |Location
!rowspan=2 |Notes
|-
!DMS
!MS
!DMSL
|-
!144003
|align=center |55803
|align=center | —
|align=center |55826
| rowspan="4" align="left" |Northern Rail (unbranded)
|Great Central Railway (Nottingham)
|Delivered on 3 September 2020.
|-
!144004
|align=center |55804
|align=center | —
|align=center |55827
|Aln Valley Railway
|Delivered on 15 December 2020.
|-
!144006
|align=center |55806
|align=center | —
|align=center |55829
|Cambrian Heritage Railway
|Delivered on 22 May 2020.
|-
!144007
|align=center |55807
|align=center | —
|align=center |55830
|Cambrian Heritage Railway
|Delivered on 22 May 2020.
|-
!144011
|align=center |55811
|align=center | —
|align=center |55834
| align="left" |MetroTrain
|Keighley and Worth Valley Railway
|Acquired on 26 June 2020.
|-
!144013
|align=center |55813
|align=center | —
|align=center |55836
| rowspan="9" align="left" |Northern Rail (unbranded)
|Telford Steam Railway
|Delivered on 1–2 July 2020.
|-
!144014
|align=center |55814
|align=center |55850
|align=center |55837
|Tyseley Locomotive Works
|For main line use.
|-
!144016
|align=center |55816
|align=center |55852
|align=center |55839
|Aln Valley Railway
|Delivered on 16–17 December 2020.
|-
!144017
|align=center |55817
|align=center |55853
|align=center |55840
|Appleby Frodingham Railway
|Acquired by Scunthorpe Industrial Heritage Railways in November 2020, in use for driver experience at British Steel Scunthorpe works.
|-
!144018
|align=center |55818
|align=center |55854
|align=center |55841
|Mid Norfolk Railway
|Delivered to Dereham in late 2020.
|-
!144019
|align=center |55829
|align=center |55855
|align=center |55852
|Tyseley Locomotive Works
|For mainline use.
|
|-
!144022
|align=center |55822
|align=center |55858
|align=center |55845
|Keith & Dufftown Railway
|Delivered on 4 September 2020
|-
!144023
|align=center |55823
|align=center |55859
|align=center |55846
|Tyseley Locomotive Works
|For mainline use.
{| class="wikitable"
!rowspan=2 |Unit
!colspan=3 |Vehicle numbers
!rowspan=2 |Livery
!rowspan=2 |Location
!rowspan=2 |Notes
|-
!DMS
!MS
!DMSL
|-
!rowspan=2 |144001
|align=center |55801
|align=center rowspan=2 | —
|align=center | —
|Northern Rail (unbranded)
|Airedale General Hospital
|"Transform a Pacer" winner, to be used as a non-clinical space for children's ward patients.
|-
|align=center | —
|align=center |55824
|Grey, with Platform 1 branding
|Huddersfield railway station
|"Transform a Pacer" winner, to be used by the Platform 1 mental health charity as an educational kitchen.
|-
!144002
|align=center |55802
|align=center | —
|align=center |55825
|TEXO Foundation (black and orange)
|The Dales School, Blyth
|To be used as a classroom and library.
|-
!rowspan="2"|144008
|align=center |55808
|align=center rowspan="2"| —
|align=center | —
|rowspan="3"|Northern Rail (unbranded)
|Fagley Primary School, Bradford
|"Transform a Pacer" winner, to be converted into a science lab to promote STEM learning.
|-
|align=center | —
|align=center |55831
|Corby and District Model Railway Society
| Used as a static exhibit, for special events and birthday parties.
|-
!144010
|align=center |55810
|align=center | —
|align=center |55833
|East Lancashire Railway
|Purchased by the Greater Manchester Fire and Rescue Service for use as a training rig, being stripped of parts prior to transfer.
|}