British Rail Class 357

British Rail Class 357 "Electrostar"
A c2c Class 357/2 No. 357206 at Upminster
The interior of a c2c Class 357/2 Electrostar
In service	1 November 1999 – present
Manufacturer	ADtranz Derby (now Bombardier Inc.)
Family name	Electrostar
Number built	74 units
Formation	4 carriages per unit DMSO(A)+MSO+PTSO+DMSO(B)
Capacity	282 seats (/0 & /2) 222 seats (/3)
Operator(s)	c2c
Specifications
Car length	DMSO: 20.75 m (68 ft 1 in) each, MSO and PTSOL: 20.10 m (65 ft 11 in) each
Width	2.80 m (9 ft 2 in)
Height	3.78 m (12 ft 5 in)
Maximum speed	100 mph (160 km/h)
Weight	157.6 t (155.1 long tons; 173.7 short tons): DMSO 40.7 t (40.1 long tons; 44.9 short tons) each, MSO 39.5 t (38.9 long tons; 43.5 short tons), PTSOL 36.7 t (36.1 long tons; 40.5 short tons)
Power output	6 × 250 kW traction motors = 1,500 kW (2,000 hp)
Electric system(s)	25 kV 50 Hz AC Overhead lines
UIC classification	2'Bo'+2'Bo'+2'2'+Bo'2'
Coupling system	Tightlock fully automatic couplers
Track gauge	1,435 mm (4 ft 8 1⁄2 in) standard gauge

The British Rail Class 357 Electrostar alternating current (AC) electric multiple units (EMUs) were built by ADtranz (now owned by Bombardier Transportation) at their Litchurch Lane Works in Derby, England, in two batches from 1999 to 2002 at a cost of approximately £292 million.

They were the first member of the Electrostar family, which also includes Classes 375, 376, 377, 378, 379 and 387, and are the most numerous type of EMU built in the post-privatisation period of Britain's railways. They have the same basic design, bodyshell and core structure as the Turbostar diesel multiple unit (DMU), which is in turn the most common post-privatisation diesel multiple unit family, and both evolved from the Class 168 Clubman design by ADtranz. The 357s are operated by c2c on the London, Tilbury and Southend Railway.

The Clubman/Turbostar/Electrostar platform is a modular design, optimised for speedy manufacture and easy maintenance. It consists of an underframe, which is created by seam-welding a number of aluminium alloy extrusions, upon which bodyside panels are mounted followed by a single piece roof, again made from extruded sections. The car ends (cabs) are made from glass-reinforced plastic and steel, and are huck-bolted onto the main car bodies. Underframe components are collected in 'rafts', which are bolted into slots on the underframe extrusion. The mostly aluminium alloy body gives light weight to help acceleration and energy efficiency. Electrostar units have a shorter 20-metre-long (65 ft 7 in) version of the Turbostar's 23-metre-long (75 ft 6 in) body as Electrostars have 3 or 4 cars per unit rather than 2 or 3 for Turbostars.