The British Rail Class 458 (or 4Jop) electrical multiple units were built by Alstom at Washwood Heath from 1998-2000. These units are part of Alstom's "Juniper" family of units, which also includes Classes 334 and 460.
Description
Thirty of these 4-car units were ordered by South West Trains in 1998, to create extra capacity and to replace some of the ageing 4Cep units, which at the time were on short-term lease. Deliveries of these units commenced in 1998. Units were delivered in SWT's mainline livery of mainly white, with a blue band, and red/orange 'swish' at cab ends.
The class suffered from major technical problems, so none of the older units were withdrawn from service. It was six more years, in 2004, before the full fleet was in service. In 2003/04, reliabilty was so dire, that despite being only six years old, it was planned to replace these units by 2005 with new Class 450 "Desiro" units. Since then reliabilty has improved sufficiently to allow them to be retained.
30 units were built, numbered 8001-8030. Each unit was formed from two outer driving motors, an intermediate trailer, and an intermediate motor. The trailer has the capacity to be fitted with a pantograph, thus allowing the units to be rebuilt in the future for overhead power collection at 25kV AC, should the need arise. The technical description of the formation is DMCO+PTSO+MSO+DMCO. Individual vehicles are numbered as follows:
- 67601-67630 - DMCO
- 74001-74030 - PTSO
- 74101-74130 - MSO
- 67701-67730 - DMCO
Operations
When first built, the units were used on the half-hourly London Waterloo to Alton trains.
Since then, the units are now almost exclusively used on Waterloo to Reading and Windsor and Eton services.
