| enginetype = Inline-6 4-stroke turbo-diesel
| displacement =
| acceleration =
| deceleration =
| aux =
| powersupply =
| hvac =
| electricsystem =
| uicclass = 1'A'+A'1'
| minimum curve = While formulating its long-term strategy for this sector of its operations, British Rail planners recognised that considerable costs would be incurred by undertaking refurbishment programmes necessary for the continued use of these ageing multiple units, particularly due to the necessity of handling and removing hazardous materials such as asbestos. In the 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 better performance than the existing fleet, particularly when it came to long-distance services. This prototype was introduced with much fanfare in June 1981. Unlike the Class 141, which featured automotive-standard wiring for the traction equipment with resulting poor performance, railway-grade wiring for the traction and braking circuits was mandated by BR for both the Class 142 and Class 143 to yield greater reliability.
Both axles (one driving per coach at the inner end) were fitted directly to the chassis rather than being mounted on bogies, unlike traditional DMUs. This uncommon arrangement has been attributed with resulting in the Class 141 units possessing a relatively rough ride, especially when traversing jointed track or points. Their comparatively poor ride quality has been said to be a major factor in the type's general unpopularity amongst passengers. As a positive result from BR's experiences with the Class 141, the Class 142 featured an improved suspension arrangement to enhance passenger comfort, this consisted of a wider spring base and double dampers being installed, features that had been deemed necessary by BR to provide sufficient levels of performance, and had been retrofitted onto all of the older Class 141s as well. caused by the long wheelbase and lack of bogies.
Upgrades and refurbishments
Starting in the early 1990s, every member of the class was mechanically upgraded due to the original parts starting to fail. Accordingly, each car was refitted with a more powerful Cummins L10 series engine – per car, which equals per twin-car unit – and Voith T211r two-stage hydrokinetic transmission,
Operations
<!-- Portions of the following section are commented out due to a complete lack of citations. -->
British Rail Provincial/Regional Railways
thumb|right|Class 142 in the original British Rail Provincial two-tone blue livery at in 1987
From new, some units were painted according to the region they operated in. For example, the first 14 Greater Manchester Passenger Transport Executive sponsored units (142001-014) received GMPTE orange and brown, then the next 13 West Country based units (142015-027) were painted in a Great Western Railway inspired chocolate and cream livery and marketed as 'Skippers'.
Canada
Unit 142049 was sent to Vancouver, Canada for Expo 86. The unit retained its Regional Railways livery and ran three trips a day all summer from Abbotsford to New Westminster. In order to operate on Canadian rails, it was equipped with radio and ditch lights, and given the designation RB100 for radio identification.
Post privatisation
Northern England
thumb|The interior of a refreshed [[First North Western Class 142]]
thumb|[[Arriva Trains Northern|Northern Spirit liveried Class 142 at Wakefield Kirkgate in 2006]]
thumb|The interior of a Northern Spirit refurbished Class 142
Upon the privatisation of British Rail, the Class 142 fleet was divided between North Western Trains in the North West and Northern Spirit in the North East.
Northern Spirit began operations in 1997 and continued until 2000. At this point, parent company MTL ran into difficulties and the company was sold to Arriva, who renamed it Arriva Trains Northern in 2001.
In 1998, ATN swapped seven Class 142s (142085-142091) for seven Class 150/2 units from Valley Lines. In October–December 2002, these were swapped for non-refurbished units 142072-77 and 080–3, as 142086-091 had only recently been refurbished by Northern Spirit and Valley Lines wished to start their refurbishment from scratch.
In 2004, First North Western and Arriva Trains Northern were merged into the Northern rail franchise, which inherited a combined fleet of 79 Class 142s.
All 79 Class 142s were painted into the Northern Rail livery. Due to rising passenger numbers in the north of England (by about 10% per annum and even by over 25% per annum at some stations where the 142s were in operation),
Five Class 142 Pacers, in service with First Great Western, were returned to Northern Rail in December 2008. The rest returned to Northern Rail by November 2011, much later than originally planned.
Despite being built for branch-line stopping services, the Class 142s were mainly used on urban commuter services in and out of cities like Liverpool, Manchester, Sheffield, Leeds and Newcastle, and were seen on longer-distance services of up to three hours including the 1632 Middlesbrough-Carlisle service nearly ; they had also been used on services between Blackpool North and Chester via Stockport, which ceased to operate in December 2008. All 79 passed with the Northern franchise to Arriva Rail North in April 2016, and any remaining units transferred to the government-owned operator Northern Trains on 1 March 2020.
In June 2020, it was announced that 13 Class 142s would be allowed to re-enter service if necessary, the units being 142004, 018, 023, 058, 065, 068, 070, 071, 078, 087, 090, 094 and 095, which they did on 6 July 2020 following the introduction of a new timetable, due to a need for extra capacity for social distancing during the COVID-19 pandemic, coupled to s so as to avoid needing to be non-PRM (persons of reduced mobility) modified.
Pacers were withdrawn from Northern Trains on 27 November 2020, the last service being the 16:36 to , operated by 142004.
<!--
Merseyside
A total of seventeen Class 142 units based at Newton Heath TMD (142041-049 and 142051-058) were refurbished for use on Merseyside Passenger Transport Executive's City Line on services around the Liverpool and Greater Manchester areas. The refurbishment included dot-matrix route indicators and a new design of individual low-backed seating, and the trains were repainted into Merseyrail's livery. Upon privatisation, these units passed to First North Western in March 1997. All of these sets were transferred to Northern in 2016, however remained in the livery of previous operator Northern Rail. -->
Wales
Valley Lines acquired its Class 142s by swapping Class 150/2 units with Arriva Trains Northern. The Class 142s were initially painted in Valley Lines livery.
Transport for Wales used its Class 142 Pacer trains on the commuter lines around Cardiff, Barry and Penarth known as the Valley lines. All of its Class 142 Pacer fleet wore the turquoise and cream house colours of Arriva Trains Wales. The Class 142 units were also primarily used on South Wales Valley line routes and routes through the Vale of Glamorgan. On Valley and Vale of Glamorgan services, Class 142s were often coupled together with Class 143 or Class 150 units to cope with demand on the busy Valley Lines network. The Class 142s received minor refurbishments with retrimmed seats in new moquette, plus the installation of ceiling-mounted CCTV cameras.
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South West England
Twelve Class 142 Pacers were received by First Great Western in 2007, and started operations in December 2007. These were loaned from Northern (where they had been stored), in part to cover for the refurbishment of FGW's Sprinter fleets but also to allow the s to be reformed as three-coach sets.
The 142s were based at Exeter TMD, working alongside the similar s on services in Devon and Cornwall, including the Avocet Line, Riviera Line and Tarka Line.
Five 142s were returned to Northern Rail in the autumn of 2008, following the completion of the refresh of Class 150 Sprinter units. The remaining seven units were returned to Northern Rail in November 2011 after being replaced by class 150 units cascaded from London Overground and London Midland.
-->
Withdrawal
All 94 Class 142s were to be withdrawn by mid-2020, as they did not comply with the Persons with Reduced Mobility Technical Specification for Interoperability (PRM-TSI).
Bidders for the Northern franchise that commenced in April 2016 were required to order new DMUs and take on Sprinters and Turbostars (Classes 150, 156, 158 and 170) released by other franchises as replacement. The Long Term Passenger Rolling Stock Strategy for the Rail Industry indicates up to 500 non-electric carriages will need to be built in the short term. Arriva Rail North withdrawals were scheduled to commence in November 2018 with the last to be removed from traffic in October 2019. This was slightly delayed until the first entered service.
Wales & Borders franchise holder KeolisAmey Wales planned to replace all of its Class 142s by mid-2020.
In August 2019, Arriva Rail North retired seven and placed them in store at Heaton TMD. Scrapping commenced in December 2019 with 142005 taken to CF Booth, Rotherham. In December 2019, three withdrawn Arriva Rail North units were transferred to Transport for Wales for spare parts.
In December 2019, both Arriva Rail North and Transport for Wales were issued derogations to allow use into 2020. Northern Trains was permitted to operate the units until 31 May 2020, but only when coupled to a compliant unit, while Transport for Wales was permitted to use the units until 31 July 2020 and could be operated alone. This was later extended to 31 December 2020 for both operators.
The final Class 142s were withdrawn from Northern Trains in November 2020 and Transport for Wales in December 2020.
Preservation
Several operational Class 142 units have been preserved and additional sets are set to be saved/earmarked for preservation; most of which so far being ex-Northern operated units with one being an ex-Arriva Trains Wales unit. The pioneer unit, 142001, is part of the National Collection and preserved at the National Railway Museum Shildon. Other units have also been purchased, but will only be used to provide spare parts to the units which are planned to operate on heritage railways or museums.
Operational
{| class="wikitable"
!rowspan=2|Unit
!colspan=2|Vehicle numbers
!rowspan=2 align=left|Livery
!rowspan=2 align=left|Location
!rowspan=2 align=left|Notes
|-
!DMS
!DMSL
|-
!align=center|142001
|align=center|55542
|align=center|55592
||Northern Rail (unbranded)
|align=center|National Railway Museum Shildon
|align=left|Operational. First unit built.
|-
!align=center|142003
|align=center|55544
|align=center|55594
|Greater Manchester PTE (orange and brown)
|align=center|LNWR Heritage, Crewe; Locomotive Services Limited
|Preserved in April 2020 and repainted at Eastleigh Works.
|-
!align=center|142004
|align=center|55545
|align=center|55595
||Northern Rail (unbranded)
|align=center|Telford Steam Railway
|Privately owned. Arrived at Telford in April 2021.
|-
!align=center|142006
|align=center|55547
|align=center|55597
|Arriva Trains Wales (unbranded)
|align=center|Llanelli & Mynydd Mawr Railway
|Arrived 15 February 2021. It is the only Arriva Trains Wales unit not to be scrapped. To be restored to Valley Lines Livery.
|-
! align="center" |142011
| align="center" |55552
| align="center" |55602
| rowspan="5" |Northern Rail (unbranded)
| rowspan="2" align="center" |Midland Railway – Butterley
| align="left" |To be used as spares for 142013.
|-
!align=center|142013
|align=center|55554
|align=center|55604
|align=left|Restored to full working condition and in original GM Colours.
|-
!align=center|142017
|align=center|55558
|align=center|55608
|align=center|East Kent Railway
|align=left|Privately owned. Preserved as "a good value and reliable form of traction to secure the long term future of the railway".
|-
!align=center|142018
|align=center|55559
|align=center|55609
|align=center|Wensleydale Railway
|align=left|Preserved on 3 March 2021. To be repainted into Skipper Chocolate and Cream livery.
|-
!align=center|142019
|align=center|55560
|align=center|55610
|rowspan="2" align=center|Waverley Route Heritage Centre
|align=left|Arrived mid-February 2020.
|-
!align=center|142020
|align=center|55561
|align=center|55611
|Merseyrail (unbranded)
|align=left|Arrived early 2020.
|-
!align=center|142023
|align=center|55564
|align=center|55614
|Northern Rail (unbranded)
|align=center|Plym Valley Railway
|align=left|Arrived late 2020.
|-
!align=center|142029
|align=center|55570
|align=center|55620
| rowspan="12" align="left" |Northern Rail (unbranded)
| rowspan="2" align=center|Chasewater Railway
|align=left|One of five sets made that display the fewest internal modifications, making it close to "original" condition.
|-
!align=center|142030
|align=center|55571
|align=center|55621
|align=left|The fourth Class 142 to be preserved, chosen due to being in close-to "original" internal condition.
|-
!align=center|142035
|align=center|55576
|align=center|55626
|align=center|Wensleydale Railway
|align=left|Possibly for use as parts donor.
|-
!align=center|142036
|align=center|55577
|align=center|55627
|align=center|East Kent Railway
|align=left|Preserved as "a good value and reliable form of traction to secure the long term future of the railway".
|-
!align=center|142038
|align=center|55629
|align=center|55579
|align=center|Mid-Norfolk Railway
|align=left|Owned by the Mid-Norfolk Railway Preservation Trust; arrived 2020.
|-
!align=center|142041
|align=center|55582
|align=center|55632
|align=center|Wensleydale Railway
|align=left|Merseyrail Class 142 variant modified with high-capacity 3+2 seating and dot matrix destination indicators.
|-
!align=center|142055
|align=center|55705
|align=center|55751
|align=center|Foxfield Railway
|align=left|Merseyrail Class 142 variant modified with high capacity 3+2 seating and dot matrix destination indicators.
|-
!align=center|142058
|align=center|55708
|align=center|55754
|align=center|Telford Steam Railway
|align=left|Arrived at Telford in April 2021.
|-
!align=center|142061
|align=center|55711
|align=center|55757
|align=center|Mid-Norfolk Railway
|align=left|Owned by the MNRPT; arrived September 2020.
|-
!align=center|142091
|align=center|55741
|align=center|55787
|}
Non-railway use
Alongside the operational preserved units, some have been acquired for non-railway use:
{| class="wikitable"
!rowspan=2|Unit
!colspan=2|Vehicle numbers
!rowspan=2 align=left|Location
!rowspan=2 align=left|Notes
|-
!DMS
!DMSL
|-
!align=center|142028
|align=center|55569
|align=center|55619
|align=center|Wensleydale Railway
|align=left|Purchased by a couple who work on the line, for conversion into a home.
|-
!align=center|142033
|align=center|55574
|align=center|55624
|align=center|Bridgend, Wales
|align=left|Acquired by South Wales Police for training.
|-
!align=center|142043
|align=center|55584
|align=center|55634
|align=center|Kingstanding Police Training Centre
|align=left|Acquired by Sussex Police for training.
|-
! align="center" |142045
| align="center" |55586
| align="center" |55636
| align="center" |Kirk Merrington Primary School, Kirk Merrington
|Acquired for use as a library.
|-
!align=center|142060
|align=center|55710
|align=center|55756
|align=center|Wensleydale Railway
|To be converted into a holiday let and arts space.
|}
Fleet details
{| class="wikitable"
|-
!Class
!Status
!Qty.
!Year built
!Cars per unit
!Unit numbers
|-
! rowspan="6" |142
| rowspan="2" |Scrapped
| align="center" |26
| align="center" |1985
| align="center" rowspan="6" |2
|142002, 142005, 142008–142010, 142012, 142015–142016, 142021–142022, 142024–142026, 142031–142032, 142034, 142037, 142039–142040, 142042, 142044, 142046–142050
|-
| align="center" |34
| align="center" |1986–1987
|142051–142054, 142057, 142059, 142062–142077, 142079–142083, 142085–142086, 142088, 142092–142093, 142095–142096
|-
| rowspan="2" |Preserved
| align="center" |21
| align="center" |1985
|142001, 142003–142004, 142006–142007, 142011, 142013, 142017–142020, 142023, 142027–142030, 142035–142036, 142038, 142041, 142047
|-
| align="center" |10
| align="center" |1986–1987
|142055, 142058, 142060–142061, 142078, 142084, 142087, 142090–142091, 142094 142043,
|}
Named units
Some units received names:
- 142009 Newton Heath 125 1876-2001 (Scrapped
- The most serious accident involving a Class 142 was at Winsford in 1999. The driver of Class 142 No. 142008 operated by First North Western, running empty from to overran a red signal on the slow line and stopped in the path of the 06:15 to Virgin Trains express, hauled by a Class 87 electric locomotive, No. 87027 Wolf of Badenoch. The impact, which caused the unit to be written off, severed the Pacer's body from its frames and caused severe internal damage. 27 people were injured, 3 seriously. Problems with engines on 142s have been experienced before.
- On 8 August 2009, Arriva Trains Wales unit 142069 derailed during an empty stock movement at Rhymney, South Wales. The unit was preparing to work a morning service with 143625 when it derailed on a set of points and hit the platform edge. 142069 was later removed by road to Cardiff Canton depot and fears were raised that the frame might have been damaged beyond repair. These fears proved unfounded and the unit later returned to service.
- On 3 October 2009, a Class 142 unit, operated by Northern Rail, hit the rear end of a departing National Express East Coast service at Darlington railway station. Three passengers from the Northern Rail train were taken to hospital with minor injuries.
- On 4 January 2010, unit 142029 collided with a train comprising two Class 159 diesel multiple units at . Nine people were injured.
- On 10 April 2011, a cardan shaft failure on 142045 led to an incident at , injuring a member of the public with a piece of ballast kicked up by the detached shaft.
- On 27 April 2012, unit 142091 was working the 1125 Lincoln – Adwick service when it hit a landslide after exiting Clarborough Tunnel near causing major frontal damage to the unit. Two people were taken to hospital with minor injuries, one of these being the driver. The landslide was blamed on heavy rain and poor drainage.
- On 9 October 2018, unit 142086 derailed at Sheffield station.
Safety criticism
In 1999, following the Winsford railway accident, the safety of the trains were criticised, with concerns regarding the crashworthiness of the design compared to modern units. In 2009, John Pugh, the then Liberal Democrat MP for Southport, described the Class 142 as "unsafe". However the UK Government's Transport Secretary at the time Geoff Hoon denied this claim saying, "I would not accept that any of that rolling stock is unsafe", and that they constantly upgrade them. In 2011, the Office of Rail Regulation (ORR) queried the safety of the Pacer trains, stating "There is particular concern over the ongoing use of Pacers beyond their intended design life." Northern Rail insisted that the trains were safe, and that they are "subject to strict regular safety and maintenance checks".
Models
- In 1987, Hornby Railways launched its first version of the BR Class 142 (Pacer) railbus in OO gauge.
- In 2019, Dapol launched a model of a Class 142 Pacer in N gauge.
- In 2020, Realtrack Models announced that it intended to produce a model of the class 142 in several liveries.