Bombardier Electrostar

The Bombardier Electrostar (sold as the ADtranz Electrostar until 2001) is a family of electric multiple-unit (EMU) passenger trains manufactured by Bombardier Transportation (formerly Adtranz) at their Derby Litchurch Lane Works in England between 1999 and 2017. It has become the most common new EMU type in the United Kingdom since the privatisation of British Rail with a number of variants. Electrostar trains are most common on high-volume suburban commuter routes around London; and on mainline services from London south to Surrey and the south coast, east to Essex, and north to Cambridge and Stansted Airport.

The model shares the same bodyshell and core structure as the Bombardier Turbostar which is the most common post-privatisation diesel multiple unit (DMU) family; both evolved from the Class 168 Clubman design by ADtranz. The Turbostar and Electrostar platforms are a modular design, sharing the same basic bodyshell and core structure, and optimised for speedy manufacture and easy maintenance. A common underframe, created by seam-welding a number of aluminium alloy extrusions, is covered by body panels and topped by a single piece roof, again made from extruded sections. Car ends (cabs) are made from glass-reinforced plastic and steel, and are bolted onto the main car bodies. Underframe components are collected in "rafts" which are bolted into slots on the underframe. The predominantly aluminium-alloy body gives light weight to help acceleration and energy efficiency.

The Electrostar was selected for use on the Gautrain system in South Africa, a new railway between Johannesburg, Pretoria, and the Johannesburg International Airport. The trains were assembled by UCW Partnership in South Africa from components made in Derby.

Transport for London (TfL) announced in August 2006 that it had ordered 48 three- and four-car Electrostar trains for the new London Overground service. These were categorised by Network Rail as Class 378, and entered service in 2009 to replace the Class 313 and Class 508 trains on the North London Line and West London Line, and to provide the opening service on the new East London line extension in 2010.

In 2009, as part of the government's wider rolling stock plan, an order was placed for thirty four-car Class 379 Electrostar units intended for use by National Express East Anglia (now operated by Greater Anglia) on the Stansted Express and West Anglia services. The first of these units entered passenger service on Thursday 3 March 2011.

Production of the trains ended in 2017 when unit number 387174 for Great Western Railway was completed at Derby Litchurch Lane Works. The family was superseded by the Bombardier Aventra.