British Rail Class 115

The British Rail Class 115 diesel multiple units were 41 high-density sets which operated the outer-suburban services from Marylebone usually to destinations such as High Wycombe, Aylesbury and Banbury which are on the Chiltern Main Line and Great Central Main Line (now the London to Aylesbury Line). Sometimes, these sets used to operate 8- or 12-car-long expresses to Nottingham Victoria in the final years of the GCML. Coincidentally, Class 115 units operated services under Table 115 in the British Rail timetable.

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 (Leyland Albion) 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)

Construction and service

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

Six sets were also built for the Cheshire Lines Committee (CLC) line between Liverpool and Manchester, 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 from Tyseley in the later years.

The Marylebone sets, which were later transferred to Bletchley but remained on Chiltern Line duties (and finally to Old Oak Common), were declared surplus after the introduction of Class 165s, from 1991 onwards. While at Bletchley and Old Oak Common depots the class found use on the Gospel Oak to Barking line, units being formed as power twins. They were, in turn, replaced on this line by Class 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 the Redhill to Tonbridge Line to replace ageing DEMU sets. The line was electrified in 1993, in order to allow a diversionary route for the Eurostar, and the class 115s were replaced initially with Class 411 EMUs, then ex-Merseyrail Class 508 EMUs in 1998 (after privatisation).

Table of orders and numbers

Lot No.	Type	Diagram	Qty	Fleet numbers	Notes
30530	Driving Motor Brake Second (DMBS)	598	30	51651–51680
30531	Trailer Open Second (TS)	590	15	59649–59663
30532	Trailer Composite with lavatory (TCL)	599	15	59664–59678
30595	Driving Motor Brake Second (DMBS)	598	12	51849–51860
30596	Trailer Open Second (TS)	590	6	59713–59718
30597	Trailer Composite with lavatory (TCL)	599	6	59719–59724
30598	Driving Motor Brake Second (DMBS)	598	40	51861–51900
30599	Trailer Open Second (TS)	590	20	59725–59744
30600	Trailer Composite with lavatory (TCL)	599	20	59745–59764

Accidents and incidents

Main article: Seer Green rail crash

On 11 December 1981, two four-car Class 115 units were involved in a collision between Gerrards Cross and Seer Green. The driver of an empty stock train, traveling from Marylebone to Princes 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 to Banbury, was, incorrectly, authorised to pass 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.

Technical details

A Class 115 at Aylesbury in 1984.

• 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)

Preservation

A set preserved on the West Somerset Railway

15 vehicles are preserved. DMBS 51677 was scrapped in early 2017.

Set number	Vehicle numbers			Livery	Location	Notes
	DMBS	TCL	DMBS
-	51655	-	-	BR Green	Private Site	Static Display
-	51669	-	-	BR Green	Midland Railway - Butterley	Stored
-	51849	-	-	BR Green	Midland Railway - Butterley	Stored
-	51859	59678	51880	BR Green	West Somerset Railway	Operational
-	51886	59761	51899	BR Green	Buckinghamshire Railway Centre	Stored
-	51887	-	-	Blood and Custard	West Somerset Railway	Under Restoration
-	-	59659(TS)	-	BR Green	Midland Railway - Butterley	Stored
-	-	59664	-	BR Green	Midsomer Norton railway station	Under Restoration
-	-	59719	-	BR Green	Dartmouth Steam Railway	Operational
-	-	59740(TS)	-	BR lined maroon	South Devon Railway	Static - in use as Station Buffet at Staverton
-	51663	-	-		West Somerset Railway	Underframe only spare parts

References

• 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