TheBritish Rail Class 165Networker Turbo is a fleet of suburbandiesel-hydraulic multiple unit passenger trains (DMUs), originally specified by and built for the British Rail Thames and Chiltern Division ofNetwork SouthEast. They were built byBREL York Works between 1990 and 1992.^[6] An express version was subsequently built in the form of theClass 166Networker Turbo Express trains. Both classes are now referred to as "Networker Turbos", a name derived some three years later for the project that resulted in the visually similarClass 365 andClass 465 EMUs.

British Rail Class 165 Networker Turbo
Great Western Railway Class 165 atGuildford
Refreshed GWR Class 165 standard-class saloon
In service	10 September 1991 – present
Manufacturer	British Rail Engineering Limited
Built at	Holgate Road Works,York
Family name	Networker Turbo
Replaced	Class 104 Class 115 Class 117 Class 119
Constructed	1990–1992
Refurbished	2003–2005 (165/0) 2010–2012 (165/1)
Number built	76 (39 × 165/0, 37 × 165/1)
Number in service	75
Number scrapped	1
Formation	2-car units:DMCL-DMS 3-car units:DMCL-MS-DMS
Fleet numbers	165/0: 165001–165039 165/1: 165101–165137
Capacity	2-car units: 186 seats(16 first-, 170 standard-class) 3-car units: 288 seats(24 first-, 264 standard-class)
Owners	Angel Trains
Operators	Chiltern Railways Great Western Railway
Lines served	Great Western Main Line Chiltern Main Line Severn Beach Line Golden Valley Line Wessex Main Line Heart of Wessex Line Avocet Line Riviera Line Tarka Line Dartmoor Line
Specifications
Car body construction	Weldedaluminium
Car length	DM vehs.: 23.50 m (77 ft 1 in) MS vehs.: 23.25 m (76 ft 3 in)
Width	2.81 m (9 ft 3 in)
Height	3.79 m (12 ft 5 in)[1]
Doors	Double-leaf sliding plug(2 per side per car)
Maximum speed	165/0: 75 mph (121 km/h)[1] 165/1: 90 mph (145 km/h)
Axle load	Route Availability 1
Prime mover(s)	2 or 3 ×Perkins 2006 TW-H(one per vehicle)
Engine type	Inline-64-stroketurbo-diesel[2]
Displacement	12.2 L (742.64 cu in)[2]per engine
Power output	260 kW (350 hp) per engine
Transmission	Voith T 211 rz(hydrokinetic, one per vehicle)
UIC classification	2-car: 2′B′+B′2′ 3-car: 2′B′+2′B′+B′2′
Bogies	Powered: BREL P3-17 Unpowered: BREL T3-17
Braking system(s)	Electro-pneumatic (disc)
Safety system(s)	AWS BR ATP (165/0 only)[1] TPWS Tripcock (165/0 only)[1]
Coupling system	BSI[3]
Multiple working	Within class, and withClasses166 and168[4]
Track gauge	1,435 mm (4 ft 8+1⁄2 in)standard gauge
Notes/references
Sourced from[5] except where otherwise noted.

The class is still in service, now operated byGreat Western Railway and byChiltern Railways. When operated originally by Network SouthEast, along with that operator's Class 166 trains, the Paddington suburban units were initially known asThames Turbos, while the units operated on the Marylebone suburban network were known asChiltern Turbos.

Externally, the class 165 can be distinguished from aClass 166 by the opening hoppers on every other window.

Thirty-nineClass 165/0Networker trains were built in 1990–91, in two batches, for the Chiltern subdivision of Network SouthEast, numbered 165001–039. Both 2-car and 3-car variants were built. Initially, thirty-three units were ordered (comprising the vehicles that made up units 165001-165022 and 165029–165039) but an additional order was placed for a further six units (165023-028). Units 165001-028 were delivered consecutively, as 2-car units, whilst units 165029-039 were delivered as 3-car units. These vehicles have a top speed of 75 mph (121 km/h). They are now all fitted withtripcocks for working over theLondon Underground lines betweenAmersham andHarrow-on-the-Hill, although upon delivery this equipment was only fitted to 165006–028.Automatic Train Protection is also fitted, making them one of the few classes to have both these features in Britain.

Each unit was formed of two outer driving motors, with an additional intermediate motor in the 3-car units. The technical description of the formation is DMOSL+MOS+DMOS. Individual carriages are numbered as follows:^[1]

• 58801-58833 (units 165001-022/029-039) and 58873-58878 (units 165023–028) - DMOSL
• 55404-55414 (units 165029–039) - MOS
• 58834-58866 (units 165001-022/029-039) and 58867-58872 (units 165023–028) - DMOS

Thirty-sevenClass 165/1Networker trains were built in 1992 for theThames line subdivision of Network SouthEast, numbered 165101–137. Like theChiltern units, both 2-car and 3-car variants were built. Units 165101-117 were delivered as 3-car units, followed by the 2-car units 165118–137. They are regeared and fitted with bogie yaw dampers to allow a top speed of 90 mph (145 km/h), more suitable for mainline use.

Each unit was formed of two outer driving motors, with an additional intermediate motor in the 3-car units. The technical description of the formation is DMOCL+MOS+DMOS. Although still listed on the vehicle data sheets at DMCL vehicles, the first-class area has been removed from 2-car 165s operated by GWR. As such these vehicles are now technically DMOSL vehicles. The 3-car units were similarly declassified, but the first-class accommodation has now been reinstated on these. Individual carriages are numbered as follows:^[1]

• 58953-58969 - DMCL
• 58879-58898 - DMOSL changed from DMCL in 2015^[7]
• 55415-55431 - MOS
• 58916-58932 and 58933-58952 - DMOS

Unit 165115 was destroyed in theLadbroke Grove rail crash.^[8]

• On 2 November 1994, unit 165102 collided with the buffer stop atSlough and damaged part of the station^[9] after it slid for 1,200 yd (1,100 m) due to slippery rails. It only reduced its speed from 56mph to 30mph upon impact, injuring two people. An inquiry found that had the train not hit the buffers it would have continued sliding for a further 910 yd (830 m) before stopping.^[10]
• Ladbroke Grove rail crash: On 5 October 1999, unit 165115 passed a signal at danger while leaving London Paddington on aThames Trains service. This resulted in a serious collision with a London-boundHST service. 31 people were killed (24 of them on board the Class 165, the leading coach of which was completely destroyed by the impact) and 417 were injured.
• On 30 June 2005, unit 165037 was approaching theGerrards Cross Tunnel, which was under construction, when the driver realised that the line was blocked. An emergency stop was made and the train came to a halt 250 to 300 yards (230 to 270 m) before the tunnel, which had partially collapsed. The train returned wrong line toDenham Golf Club where the passengers were detrained.^[11]
• On 16 June 2016, unit 165124 was derailed by a set oftrap points atPaddington afterpassing a signal at danger, causing significant disruption to services. The driver's assistant's side of the cab was destroyed after the train hit a stanchion that holds up the overhead catenary after derailing. The vehicle was moved after two days in position at Paddington to Old Oak Common Depot to be taken away by road for assessment and repair work.^[12]
• Unit 165128 was in service as a hybrid unit with 58609 (MOS vehicle from 166209) inserted in the middle from November 2015 until May 2016. This was due to one of its driving vehicles being damaged in an engine fire on the North Downs line in November 2015,^{[clarification needed]} rendering it out of service, and so to provide another 3-car train in service.^[13]
• On 21 June 2020, units 165015 and 165006 formed a passenger train thatpassed a signal at danger (a SPAD) and was in danger of colliding head-on with a passenger train formed ofLondon Underground S stock atChalfont & Latimer. The two trains stopped 25 yards (23 m) apart. Driver fatigue was found to be the cause of the SPAD.^[14]

The 165/0 units were originally delivered inNetwork SouthEast livery for used on routes including fast services fromLondon Marylebone toPrinces Risborough andBanbury and local services fromAylesbury to London and Princes Risborough. In this role they replaced theClass 115 DMUs. They were later used further afield, when Chiltern services were extended to serveLeamington Spa,Warwick,Solihull andBirmingham Snow Hill /Birmingham Moor Street railway station.

In December 1993, due to a downturn in traffic as a result of the recession, units 165001-007 were transferred from the Chiltern lines of Network SouthEast to the Thames lines (from Aylesbury to Reading depots). All vehicles had their tripcock equipment removed before transfer. The following year, unit 165007 was returned to the Chiltern lines, followed by 165006 in 1995. Due to unavailability of tripcock equipment upon their return, the units were coupled cab-to-cab and operated for some months between the vehicles of other units as semi-permanently formed four-car units - until tripcock equipment became available, allowing them to be restored to operational two-car units. Following privatisation, two former Chiltern units (165003 and 165005) were repainted intoThames Trains livery.Chiltern Railways inherited 34 Class 165/0 units from Network SouthEast, and the remaining five were returned from Thames Trains in 2004 - leaving Chiltern Railways operating the whole subclass.

After privatisation they continued to work similar services as before but, with the arrival of the fasterClass 168Clubman units, the 165Turbo trains were displaced and are now found less often on expresses to Birmingham, generally working on shorter routes such as stopping services toAylesbury,High Wycombe, andStratford-upon-Avon and also theBirmingham Moor Street -Leamington Spa local services.

A new depot was built at Aylesbury in 1990/1991 for the maintenance of these trains and has been enlarged since British Rail days, with the addition of a wheel lathe. Light maintenance and refuelling is carried out at Wembley LMD andTyseley TMD, and units can occasionally be found atStourbridge LMD. Units are also regularly stabled in the Marylebone station environs, Aylesbury South Sidings and at Banbury, where a further depot is currently under construction at the south end of the station on the western side of the line.

All Chiltern units were refurbished between late 2003 and early 2005.^[6] Air conditioning was added and the opening hopper windows replaced with sealed units. A new passenger information system, similar to that on the Class 168Clubman trains,CCTV cameras and an area designated for the use of wheelchair users were added and the first-class section was removed, as Chiltern became a standard-class-only railway in 2003. The original 3+2 seating at the outer ends of the driving vehicles was replaced by new 2+2 high-back seating. The existing 3+2 low-back seating was retained in the centre areas of the driving vehicles and throughout the centre vehicles of the three-car units. A cycle/wheelchair area with tip-up seats was also added to each unit. A further refurbishment began in 2015, concentrating on the toilet areas, to make these units fullyDisability Discrimination Act 1995 (DDA)-compliant for operation beyond 2020.

They can often be found on the Aylesbury to London Marylebone routes including the Princes Risborough shuttle.

The Class 165/1 fleet were built for local services fromLondon Paddington along theGreat Western Main Line; their main destinations included local trains toReading,Greenford,Newbury,Bedwyn, Oxford, andBanbury, and services along the branch lines toWindsor & Eton Central,Henley-on-Thames,Marlow andBicester Town.

Following theprivatisation of British Rail, the franchise was won by theGo-Ahead Group, who operated it asThames Trains from 1996 to 2004 and inherited all the Class 165/1Turbo trains as well as the first five Class 165/0Turbo trains that had been transferred from the Chiltern lines. In April 2004, operation of the Thames Trains franchise passed toFirst Great Western Link. In 2004, due to deliveries of newClass 180Adelante units on sister companyFirst Great Western, the five Class 165/0Turbo units became redundant and were transferred toChiltern Railways.

In January 2010, First Great Western announced an £8 million refurbishment programme for its fleet of Classes 165 and 166 Turbo DMU trains:^[15]

• seats re-trimmed
• interiors repainted
• Passenger Information Displays replaced with a GPS-based system
• upgraded lavatory facilities
• flooring stripped and replaced

In 2012, First Great Western took delivery of Class 180Adelante units forCotswold Line services, and three-carClass 150Sprinter units forReading to Basingstoke Line services, allowing Class 165 and 166 units to be used to reinforce Thames Valley services.^[16]

In late 2015, as part of the rebranding to GWR, the Class 165 fleet had all first-class sections removed to increase capacity.^[7]

Following the electrification of theGreat Western Main Line up to Didcot Parkway, as well as theReading-Taunton line as far as Newbury, services between London Paddington and Didcot Parkway, as well as between Reading and Newbury, have been operated by newClass 387electric multiple units,^[17] allowing much of the existing Class 165 fleet to move to the Bristol area. Class 165s continue to service the aforementioned branch lines, but no longer run to London Paddington except during peak hours.

Following the transfer of the 166 units toSt Philip's Marsh depot in July 2017, some of the 165 services have since followed on with the first 165 operating in the Bristol area in July 2018. Since then and alongside the 166s, they have rapidly been introduced on other services such as theWeston-super-Mare toFilton Abbey Wood (nowWeston-super-Mare /Bristol Temple Meads toSevern Beach /Filton Abbey Wood) services, theCardiff Central toTaunton services, theGolden Valley Line, theHeart of Wessex Line and also some services on theWessex Main Line as far asWarminster andSouthampton Central. In January 2019, they began operating the regional service betweenCardiff Central andPortsmouth Harbour which allowed more of theClass 158 units that solely operated this service to move more west.^[18]

The transfer of the 165 (and 166) units to services in and aroundBristol andExeter have overall allowed units that previously operated these services to move further west, such as theClass 150 and Class 158 units.^[19] More so than the 166 units, a lot of the 165 units remain to be based atReading TMD where they continue to operate Thames Valley services.

Some units have been named these are as follows:

• 165119Norman Topsom MBE^[21]
• 165120Roger Watkins The GWR master train planner^[22]

It was reported in September 2018 that Angel Trains was to convert class 165 units for Chiltern Railways tohybrid diesel and battery-powered trains.^[23]

In April 2020, two-car unit 165004 was sent to LORAM rail at Derby for HyDrive conversion.^[24]

In August 2023 it was announced that the project had been abandoned.^[25]

• "Class 165s ordered".RAIL. No. 93. EMAP National Publications. 6–19 April 1989. p. 7.ISSN 0953-4563.OCLC 49953699.