British Rail Class 155

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British Rail Class 155 Super Sprinter
Arriva Rail North Class 155 at Hull Paragon in 2019
The interior of a Northern Rail Class 155
In service	1987–present
Manufacturer	Leyland Bus
Order no.	31057 (DMSL vehicles) 31058 (DMS vehicles)[1]
Built at	Workington[2]
Family name	Sprinter
Replaced	BR First-Generation DMUs
Constructed	1987–1988
Entered service	1988[2]
Refurbished	2006–2007
Number built	42 (35 converted to Class 153)
Number in service	7
Formation	2 cars per unit: DMSL-DMS[2]
Diagram	DMSL vehicles: DP248 DMS vehicles: DP249
Fleet numbers	First order: 155301–155335 (all converted to Class 153) Second order: 155341–155347[3]
Capacity	160 seats[4] (80 per vehicle)[1]
Owners	Porterbrook[5]
Operators	Current: Northern Trains Former: Arriva Trains Northern Northern Rail Arriva Rail North Regional Railways
Depots	Botanic Gardens TMD (Hull)
Lines served	Harrogate Line Hull to Scarborough Line Hull to York Line
Specifications
Car body construction	Steel
Car length	23.208 m (76 ft 1.7 in)
Width	2.700 m (8 ft 10.3 in)
Height	3.746 m (12 ft 3.5 in)
Doors	Single-leaf sliding plug (2 per side per car)[3]
Wheelbase	Bogies: 2.6 m (8 ft 6 in) Bogie centres: 16.0 m (52 ft 6 in)
Maximum speed	75 miles per hour (121 km/h)
Weight	DMSL: 38.8 t (38.2 long tons; 42.8 short tons) DMS: 37.9 t (37.3 long tons; 41.8 short tons)[note 1]
Prime mover(s)	2 × Cummins NT855-R5[3][1] (one per vehicle)
Engine type	Inline-6 4-stroke turbo-diesel[7]
Displacement	14 L (855 cu in) per engine[7]
Power output	430 kW (570 hp) total
Transmission	Voith T 211 r (hydrokinetic) (one per vehicle)[3]
HVAC	Warm air & hot-water radiators
UIC classification	2′B′+B′2′
Bogies	Powered: BREL P3-10 Unpowered: BREL BT38
Minimum turning radius	90 m (295 ft 3 in)
Braking system(s)	Electro-pneumatic (tread)
Safety system(s)	AWS TPWS
Coupling system	BSI
Multiple working	Within class, plus Classes 14x, 15x, and 170[3]
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Notes/references
As-built specifications sourced from [6] except where otherwise noted.

The British Rail Class 155 is a diesel multiple unit passenger train. These DMUs were built by Leyland Bus at Workington (incorporating some Leyland National bus components) between 1987 and 1988 as part of BR's replacement of its ageing first-generation diesel fleet. 42 units were originally built, of which only 7 remain; the other 35 units were converted to Class 153 railcars.

By the beginning of the 1980s, British Rail (BR) operated a large fleet of first generation DMUs, which had been constructed in prior decades to various designs.^[8] While formulating its long-term strategy for this sector of its operations, British Rail planners recognised that there would be considerable costs incurred by undertaking refurbishment programmes necessary for the continued use of these aging multiple units. Planners instead examined the prospects for the development and introduction of a new generation of DMUs to succeed the first generation.^[9]

The initial specification was relatively ambitious, calling for a maximum speed of 90 mph (145 km/h), acceleration comparable to contemporary EMUs.^[9] This specification led to the experimental British Rail Class 210 diesel-electric multiple unit. However, it was found to be expensive, and it was recognised that a production model assembled from proven components would possess greater reliability and lower maintenance costs; an availability rate of 85 percent was forecast.^[9]

By 1983, experiences with the Class 210 had influenced BR planners to favour procuring a new generation of DMUs, but to also adopt a new specification that were somewhat less demanding than before.^[9] Specifically, it was decided to drop the top speed from 90 mph to 75 mph, as testing had revealed the higher rate to deliver no perceivable improvement in journey times due to the typically short spacing of the stations the type was intended to serve.^[9] The requests for compatibility with other rolling stock were eliminated, although auto-coupling and auto-connecting functionality was added. In addition to a good ride quality, the specification included a sound level of 90 dB when at full speed, an operational range of 1,000 miles, and an interval between major overhauls of five years or 350,000 miles.^[9]

The bid submitted by British Rail Engineering Limited (BREL) was heavily based on its successful Class 455 EMU, sharing its body and the majority of its running gear, albeit equipped with two different power trains.^[9]

The resulting Class 150 was viewed as unsatisfactory for more-upmarket services. Studies showed coaches could be stretched, providing more internal volume and thus enabling the somewhat cramped two-by-three seating arrangement of the Class 150 to be substituted with a more roomy two-by-two counterpart. These changes could be implemented without impacting much of the benefits of adopting the existing design.^[9]

It was identified that this would result in a weight increase and thus a decreased power-to-weight ratio, but it was determined that the performance of the proposed DMU was only slightly lower, and it could achieve similar journey times across the intended cross-country routes as the Class 150.^[9] It was also found that, while there was a slight increase in fuel consumption due to the changes, the envisioned DMU had lower fuel consumption than locomotive-hauled trains and lower maintenance costs. Accordingly, it was decided to proceed with developing a detailed specification and issuing it to industry.^[9] Amongst the requirements listed in the issued specification was the explicit statement of the acceptability of the proven power trains of both the Class 150 and Class 151.^[9]

Class 155 units are formed of two 23-metre-long (75 ft 6 in) vehicles, a stretch of 3 m (9 ft 10 in) per vehicle compared to Class 150 units.^[9] Each vehicle is fitted with an underfloor-mounted Cummins NT855-R5 turbo-diesel engine, producing up to 213 kW (285 hp), driving both axles of the inside-end bogie via a Voith hydrokinetic transmission.^[1]

The fleet was part of the "Super Sprinter" build, the other part of which was the Class 156 fleet - though only the latter carried the "Super Sprinter" branding. They were manufactured by British Leyland, who used similar construction techniques to those used on the more basic Pacer railbuses. The relatively lightweight body, which was mounted on a welded floor assembly, comprised a series of pre-formed panels that were fixed together via the extensive use of Avdel rivets. The body is lined with a somewhat large number of windows, which is said to make the coaches appear unusually long; despite considerations towards adopting sealed windows to reduce noise levels, the windows are openable for natural ventilation.^[9] It has been observed that, as a byproduct of the vehicle's lightweight construction and length, certain coaches have exhibited a slight, but visible, sag.^{[citation needed]}

The Class 155 was introduced to service at a rapid rate, despite the presence of some teething issues with the type. The units were the first BR DMUs to be furnished with sliding-plug automatic doors which closed to provide a smooth bodyside rather than sliding back into the bodyshell (the system used with 150s and 151s). During their early service, it was found that these doors often failed to work properly; there were reports of the doors opening while the trains were in motion.^{[citation needed]} Consequently, the fleet was temporarily taken out of use and modified, while the 156s were assigned to perform their diagrams as an interim measure.^{[citation needed]}

Following this modification work, the performance of the Class 155 improved substantially. An emerging requirement for replacement rural lines stock ultimately led to the decision to convert the majority of the Regional Railways' Class 155 fleet into a single car configuration, enabling these units to replace the elderly 121 and 122 "Bubblecar" units. Originally, it had been intended for these single-car units, which had been introduced roughly 30 years prior, to be withdrawn and entirely replaced by the incoming Pacer fleet; however, experience with the Pacers determined that they were unable to work the sharply-curving steeply-graded branchlines involved. Instead, the Pacers were moved to replace a number of Class 150s, the 150s took over certain 156 diagrams, and the 156s took on the 155 services which were not handed over to the new Class 158s. The 155s emerged from the workshops as single car Class 153s, and were put to work augmenting two car units and on the quiet Cornish, Welsh, North-Western, Norfolk and Lincolnshire branch lines. They did not operate North of the Scottish border before 2020. However, West Yorkshire Passenger Transport Executive refused to allow the seven units which they owned to be converted, and these were merely modified to operate reliably in original form. The conversion to single car units was notable for not requiring any external doors to be moved, although this has led to the No.2 cab being unusually cramped, despite being extended into the vestibule area.^{[citation needed]}

The previously mentioned seven remaining Class 155 units, which are numbered 155341 to 155347, were constructed in 1988 for West Yorkshire Passenger Transport Executive (WYPTE) for their MetroTrain services, and have continued to serve in their original formation across multiple decades. The type is currently operated solely by Northern Trains. They were previously frequently seen on Manchester Victoria to Leeds services but, as of 2024, the Class 155s are allocated to Botanic Gardens TMD and mostly operate routes through Hull.^{[citation needed]}

Illustration of a Class 155 unit in Arriva Rail North livery

In 2000, Hornby Railways launched its first version of the Class 155 in OO gauge.^[10]

Wikimedia Commons has media related to British Rail Class 155.

• Train Testing site - pictures of class 155 testing and early service running