Class 159

On completion of the Bournemouth to Weymouth electrification in 1988, and the deployment of then new Class 442 ‘’Wessex Electric’’ EMU stock on the whole route from London, Network SouthEast turned its attention to modernising the non-electrified line to Salisbury and Exeter. Class 50s had been fronting BR Mk 2a stock on the route since May 1980, but despite these locomotives having received refurbishments at Doncaster between 1979 and 1983, unreliability again began to plague their existence. In addition to frame cracking (caused by the stretch of line between Waterloo and Woking), the Class 50s were not suitable for the frequent stop-start service patterns employed on the ex-LSWR route. Large quantities of electrical current from the generator, regularly required by the traction motors to start heavy trains from standstill, caused component and wire burnouts. On the Western Region, the type better performed on those long-distance services from Paddington, which involved fewer station calls and a greater amount of time spent running at high speed. Although Class 47/7s began appearing on Waterloo to West of England duties in a large form during Summer 1991, this transpired to be a temporary solution.
 
Electrification of the Salisbury route from Worting Junction, if only in part, was one of the modernisation proposals in the frame. With the expense of installing third rail all the way to Exeter, there were hints of a cost compromise: the implementation of a diesel push-pull operation, similar to that which had formerly been in place between Bournemouth and Weymouth. If third rail was able to reach at least Salisbury (today considered as part of the London ‘’commuter land’’), diesel haulage could still fill the breach thereafter to Exeter. However, this operational system was deemed unsatisfactory, and in addition to cost grounds, electrification of the whole route was also viewed as unviable as a result of sections of the line being subject to regular flooding. Initially, NSE’s preferred solution to this predicament was a diesel variant of its recently-deployed Class 442 EMU, but doubts soon surfaced over the suitability of the Mk 3 coach body to accommodating a diesel engine. To modify the Mk 3 to incorporate an engine - either under-slung or located within the body shell itself - would be expensive, and not necessarily produce the desired results. Whilst half-length HST formations had been mooted as an option, traditional locomotive haulage on the route was not ruled out. In the late 1980s, the ‘’InterCity’’ Business Sector had devised plans for a new locomotive to replace Class 47s on its Cross-Country services. Promoted as ‘’Class 48’’, the project was due to be a follow on from the also proposed ‘’ InterCity 250’’ scheme. The latter involved providing the West Coast Main Line with new high-speed stock with tilting capability, which comprised of an uprated variant of the Class 91, complete with 26 metre-long Mk 5 carriages. This would level the playing field with the East Coast Main Line, which by this time was receiving InterCity 225 electric train sets. With reference to the Class 48, it was envisaged that the locomotive would demonstrate a common body shell with the Class 60 (and, latterly, Class 92), although would incorporate a streamlined cab and utilise bogie sets derived from the unique Class 89. As far as InterCity’s Cross-Country services were concerned, it was proposed that the new variant would haul Mk 3 coaching stock displaced from the West Coast Main Line as a result of the InterCity 250 project. An additional Class 48 order was seen as a possible solution to NSE’s modernisation requirements on the Salisbury line.
 
Meanwhile, in January 1989, formal government approval and funding was received by the ‘’Provincial Railways’’ Business Sector for the procurement of 138 new DMU vehicles. These would be formed into two and three-vehicle ‘’Class 158’’ sets and replace the sector’s locomotive-hauled stock. In April of the same year, a follow-on order worth £20 million was placed for the production of a further 56 vehicles of the same class, in accordance with the projected passenger growth forecasted. Once the orders had been finalised with British Rail Engineering Limited and construction began, the Provincial sector realised that it had over-estimated potential passenger numbers, therefore had too much new stock on order. Due to ownership changes at BREL, the contractor having been privatised in February 1989, it was not possible to reduce the order size, which posed the problem of surplus stock. However, all was not necessarily lost. With the Treasury having a tight hold on the purse strings, the aforementioned Class 48 locomotive scheme was abandoned, and InterCity also had to halt the InterCity 250 project due to lack of funding. Thus, NSE’s locomotive-hauled option on the Waterloo to Exeter route became increasingly unlikely, especially now that the surplus Class 158 stock situation presented itself. In October 1990 it was announced that NSE was seriously considering offloading the additional three-vehicle variant Class 158 units from the Provincial sector. On 19th November of the same year, the decision to acquire 69 Class 158 vehicles to form three-car units on the Waterloo to Exeter route was formally approved by the government. As part of NSE’s new stock procurement, approval was also acquired for the construction of a maintenance facility at Salisbury, to house the DMU fleet. A 380-foot long depot building, accommodating four tracks, was to be established on the site of the former GWR terminus station, and sandwiched in-between it and the existing SR station were to be five floodlit stabling sidings. The Treasury formally allocated money to the whole scheme on 19th November 1991.
 
Envisaged to enter service in September 1992, before deploying the three-vehicle welded-aluminium Class 158 fleet, NSE required a partial rearrangement of the seating layout. As the now private BREL was inflexible when it came to altering order specifics, it was agreed that half of a driving trailer in each three-vehicle unit would be left without any seats. This would allow another contractor, ‘’Babcock Rail’’ of Rosyth Naval Dockyard, to install 2 + 1 First Class seating in the vacant space (comparing with Scottish-based Class 158 units which had 2 + 2 First Class seating). The outer NSE livery and internal upholstery on the existing seats were applied and installed by BREL. This internal modification was enough to re-designate the NSE three-vehicle units as ‘’Class 159’’.
 

On Saturday 11th September 1999, No. 159019 is depicted at Salisbury pairing with unit No.

159011, forming the 10:25 service to Waterloo. Both units were still displaying Network

SouthEast colours at this time. Toilet retention tanks are features of Class 159s, but not

of Class 158s. David Glasspool Collection

A clean No. 159008 is seen departing Yeovil Junction for Exeter St David's on 1st June 2004. The

colour scheme seen here was applied from 1999 onwards. The units are powered by a Cummins

NTA 855R 400 HP diesel engine, which compares with the power plant of 350 HP fitted to the

two-vehicle Class 158 units. David Glasspool

No. 159012 is seen at the end of its journey on 18th July 2005: Exeter St David's. In this view, the

unit, pairing with a second Class 159, is seen passing over the level crossing at the northern end

of the platforms, making its way to the stabling sidings. The type has a top speed of 90 MPH and

can seat 196 passengers. David Glasspool

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