Arriva Trains Wales Class 158 fleet
Livery is Arriva / Welsh Government blue
The Class 158 diesel railcars were built from 1989 to 1992 at Derby Works, being the final development of the British Rail 'Sprinter' concept, and among the very last trains to be built for the nationalised railway.
They exist in both 2-car and 3-car versions; most are fitted with Cummins engines, but a batch of 2-car sets has Perkins engines; all Arriva Trains Wales (ATW) units are of this latter type. Originally the ATW fleet was larger, but some were transferred away to other companies from 2006 when all the Class 175 fleet became available for ATW use, leaving 24 Class 158 sets in ATW service, owned by Angel Trains and leased to Arriva.
In 2009, 158s work all services on the Cambrian lines west of Shrewsbury, and share Holyhead - Cardiff and most trains on Arriva's services to Birmingham International. They also appear on the Cardiff - Gloucester route and one or two other services. General maintenance is carried out at a purpose-built new depot at Machynlleth on the Cambrian lines.
Like the Class 175s, 158s are not currently permitted on the Wrexham - Bidston and Conwy Valley lines, due to the longer station stops needed because the doors are at the ends and open slowly. There is also said to be a risk that the 'yaw dampers' on the bogies might strike some of the platforms on the Conwy Valley line.
The Cambrian lines used Radio Electric Token Block signalling from 1989 to 2011: all ATW 158s were fitted with this equipment, which was scheduled to be replaced in 2009 with the new European standard ERTMS equipment which Network Rail have volunteered to try on the Cambrian lines. 158 829 was the first to be fitted, and was used for overnight trials from late 2008. The fitting of the new equipment requires a cabinet to be installed in the passenger compartment, replacing part of a luggage rack at one end of one vehicle. An problem was encountered with sunlight affecting the driver's view of the system's display screen; an experimental solution has been to fit 'louvres' over one of the cab side windows on the driver's side.
After a pilot implementation on the Harlech - Pwllheli section for a few months, the ERTMS system, with its control centre at Machynlleth, finally took over the whole Cambrian system from Sutton Bridge Junction, Shrewsbury to Aberystwyth and Pwllheli, from March 2011.
Technical data (ATW units)
Engine: Each vehicle has a Perkins diesel 2006-TWH of 350hp at 2100 rpm, driving one bogie.
Transmission: Hydraulic, Voith T211r
Maximum speed: 90 mph (145 km/h)
Body structure: welded aluminium
Length: 22.57 metres each car
Will work in multiple with: Class 142-144, 150, 153, 155, 156, some Class 170.
Weight of each coach: between 37.5 - 38.5 tonnes.
Toilets: one per car
Doors: Bi-parting swing plug type
Couplers: BSI automatic between sets, semi-permanent bar within sets.
Brakes: Disc, electro-pneumatic operation.