British Rail Class 115
A Class 115 at Marylebone in April 1981.
In service	1960–1998
Manufacturer	BR Derby
Family name	First generation
Replaced	Steam locomotives and carriages
Number built	41 four-car sets
Number preserved	15 cars 9 (DMBS) 4 (TCL) 2 (TS)
Successor	Class 165
Formation	DMBS–TCL–TS–DMBS
Capacity	DMBS: 78 Second; TCL 30 First, 40 Second; TS: 106 Second; 4-car total: 30 First, 302 Second
Operators	British Rail
Lines served	Chiltern Main Line,London to Aylesbury Line
Specifications
Car length	63 ft 6 in (19.35 m)
Width	9 ft 3 in (2.82 m)
Maximum speed	70 mph (110 km/h)
Weight	135 long tons (137 t; 151 short tons) trainset
Prime mover(s)	Two 230 hp (172 kW)BUT (LeylandAlbion) per DMBS
Power output	920 hp (686 kW) per set
Auxiliaries	Albion
Safety system(s)	AWS, Tripcock
Multiple working	■ Blue Square
Track gauge	4 ft 8+1⁄2 in (1,435 mm)

TheBritish Rail Class 115diesel multiple units were 41 high-density sets which operated the outer-suburban services fromMarylebone usually to destinations such asHigh Wycombe,Aylesbury andBanbury which are on theChiltern Main Line andGreat Central Main Line (now theLondon to Aylesbury Line). Sometimes, these sets used to operate 8- or 12-car-long expresses toNottingham Victoria in the final years of the GCML. Coincidentally, Class 115 units operated services under Table 115 in theBritish Rail timetable.

Based on the basic Derby high density design, the sets are similar toClass 127 but were internally superior as the class had larger windows, better furnishings, lighting and wall surfaces.

Six sets were also built for theCheshire Lines Committee (CLC) line betweenLiverpool andManchester, where in 1960 they replaced steam haulage on the limited stop services via Warrington. These units lasted on the CLC until the mid-1980s when the principal services on that line became locomotive-hauled once again using Class 31 diesels. The CLC units were then transferred to join the identical ones at Marylebone.

Class 115 units also worked fromTyseley in the later years.

The Marylebone sets, which were later transferred toBletchley but remained onChiltern Line duties (and finally to Old Oak Common), were declared surplus after the introduction ofClass 165s, from 1991 onwards. While at Bletchley and Old Oak Common depots the class found use on theGospel Oak to Barking line, units being formed as power twins. They were, in turn, replaced on this line byClass 117 power twins, displaced from Paddington suburban duties.

The final class 115 working out of Marylebone was on 29 July 1992. The Tyseley vehicles survived a bit longer, until February 1994.

Some of the class briefly found their way on to theRedhill to Tonbridge Line to replace ageingDEMU sets. The line was electrified in 1993, in order to allow a diversionary route for theEurostar, and the class 115s were replaced initially with4CEP EMUs, then ex-MerseyrailClass 508 EMUs in 1998 (after privatisation).

On 11 December 1981, two four-car Class 115 units were involved in a collision betweenGerrards Cross andSeer Green. The driver of an empty stock train, traveling from Marylebone toPrinces Risborough, had stopped in the cutting between Gerrards Cross and Seer Green, to clear tree branches that were overhanging and had fallen onto the track, due to very heavy snow fall. Behind the empty stock train, a passenger train travelling from Marylebone toBanbury, was, incorrectly, authorised topass a signal at danger at Gerrards Cross, entering the same section of track and partially telescoped the stationary train. Four people were killed, including the driver of the passenger train, and five others were seriously injured.

• Builder:BR Derby
• Introduced: 1960
• Coupling Code: Blue Square
• Body: 63 ft 6 in (19.35 m) × 9 ft 3 in (2.82 m)
• Engines: BUT (Leyland Albion) of 230 hp (172 kW) (2 per DMBS)
• Transmission:Standard mechanical
• Weight: DMBS 38 long tons (39 t; 43 short tons); TCL 30 long tons (30 t; 34 short tons); TS 29 long tons (29 t; 32 short tons)

15 vehicles are preserved. DMBS 51677 was scrapped in early 2017.^[1]

Wikimedia Commons has media related toBritish Rail Class 115.

• The Railcar Association
• Motive Power Recognition: 3 DMUs. Colin J. Marsden
• British Railway Pictorial: First Generation DMUs. Kevin Robertson
• British Rail Fleet Survey 8: Diesel Multiple Units- The First Generation. Brian Haresnape
• A Pictorial Record of British Railways Diesel Multiple Units. Brian Golding

• British Rail diesel multiple units
• Train-related introductions in 1960

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