The current Thameslink routes are served by a fleet of class 319 electrical multiple units (EMUs) which were built by British Rail Engineering Ltd. (BREL) in the UK. Over the next few years, as the Thameslink Programme progresses, a number of additional routes will be incorporated into the Thameslink network. The services on these routes are currently operated by class 317 EMUs also built by BREL in the UK, class 365 EMUs built by ABB Transportation (the successor to BREL) in the UK and class 375 and 377 Electrostar EMUs built by Bombardier Transportation (the successor to ABB) in the UK.