Class 317 [Updated]

The Class 317 EMU is another class of multiple unit based on the Mark 3 coach design similar to the Classes 150 and 455 among others. Built in the early 1980s they are hard working veterans still carrying thousands of passengers daily into London. The 317 was the first British Rail multiple unit designed for driver only operation though this did result in a delay in their introduction into service because of a dispute with the unions [1][2]. All of the 317's service life to date has been on suburban services to London from the likes of Bedford, Luton and Cambridge though for a time in the late 1980s they did venture as far afield as Birmingham.

Number built: 288 (72 4-car sets)
Built: 1981-82, 1985-86
Builder: BREL York
Engine: 4 GEC G315BZ traction motors (25kV AC OLHE)
Power: 1, 328 hp (990 kW)
Formation: Driving Trailer Standard Open (DTSO)+Motor Standard Open (MSO)+
Trailer Composite Open (TCO)+DTSO

The Class 317 was built in two batches, the first batch 317/1 was built for St Pancras to Bedford services. A second batch 317/2 was built a little later for services out of Kings Cross. In the late 1990s some units were refurbished and upgraded, including fitting a new pantograph, as the 317/6. In the mid-2000s some 317s were refurbished as 317/7 for the Stansted Express, 317/5 for Greater Anglia services while others were refurbished and updated as 317/8.

Despite a long life already the 317 could remain in service for another 20 years with plans for a major rebuild and refurbishment and the fitting of new traction motors and equipment however if this life extension does take place it will be on different rails to where they are at present. They are due to be replaced by new Electrostar and Aventra EMUs from current routes over the next couple of years.

317 652 at Cambridge Heath

317 667 at Liverpool Street

Another view of 317 652 at Cambridge Heath
[1] Alec Swain, Overhead Line Electric Multiple-Units (Ian Allan, 1990) p. 71
[2] John Glover, BR Diary 1978-1985 (Ian Allan, 1985) p. 81