British Rail Class 332

British Rail Class 332
Heathrow Express EMU 332005 at Paddington
The interior of refurbished Standard Class accommodation aboard a Class 332
In service	23 June 1998 - 29 February 2016 12 March 2016 - Current
Manufacturer	CAF and Siemens
Built at	Zaragoza, Spain
Refurbishment	2012-2013
Number built	14 trainsets
Formation	4-5 cars per set
Capacity	175 seats (4 cars) 239 seats (5 cars)
Operator(s)	Heathrow Express
Specifications
Maximum speed	100 mph (161 km/h)
Weight	188.4 t (185.4 long tons; 207.7 short tons) (4 cars) 233.6 t (229.9 long tons; 257.5 short tons) (5 cars)
Power output	1.4 MW (1,900 hp)
Electric system(s)	25 kV 50 Hz AC Overhead
Braking system(s)	Regenerative and air brake
Safety system(s)	AWS, ATP
Track gauge	1,435 mm (4 ft 8 1⁄2 in) standard gauge

British Rail Class 332 electric multiple units are used by Heathrow Express between London Paddington and Heathrow Airport.

The fleet was originally ordered as Class 331 from CAF and Siemens, and was built in 1997-1998 at the former’s factory in Zaragoza, Spain. There are 14 four/five carriage units. There were original plans for this fleet not to have yellow warning panels on the front of the trains, but these plans were not approved due to safety reasons from Network Rail.

The units have Automatic Train Protection (ATP) equipment, one of the few fleets in the UK to do so. This is largely as a consequence of the Paddington-Heathrow route being mainly on the Great Western Main Line, which was equipped with ATP in the early 1990s as part of a trial of the system by British Rail.

The units are not fitted with Train Protection & Warning System (TPWS). A derogation was issued in 2001 which exempted the class from mandatory TPWS installation.

The units were the first electric trains to operate over the Great Western Main Line out of Paddington when the line was electrified as far as Airport Junction.

The 332s were originally constructed as three-car sets and were for the initial Fast Train service which started in a January 1998. Fast Train ran between Paddington and the temporary single platform siding station called Heathrow Junction. Heathrow Junction was constructed on the down side of the Down Airport line just before the tunnel portal. After the opening of the airport stations, the full Heathrow Express service started and the units were gradually increased to four cars. In 2002 five units were lengthened to five cars, allowing trains of up to nine cars to be operated.