British Rail Class 142 Pacer

The BR Class 142 Pacer was the most numerous variant of the controversial Pacer family of lightweight diesel multiple units, with 96 two-car sets built between 1985 and 1987 by BREL Derby in conjunction with Leyland Bus. The Pacer concept arose from a BR initiative in the early 1980s to replace ageing first-generation DMUs on lightly-used rural and secondary routes with vehicles that could be produced quickly and cheaply by adapting existing bus body technology to railway use. The Class 142 used the body of the Leyland National bus, one of the most widely-used single-deck buses in Britain, mounted on a specially-designed four-wheel railway underframe.

The Leyland National body was fitted with railway-standard couplings, buffers, and gangway connections and mounted on two four-wheel bogies (not conventional railway bogies — the underframe used two four-wheel sub-frames). Each power car was driven by a Cummins LTA10-R or NT855-R diesel engine through a hydraulic torque converter, giving a maximum speed of 75 mph. The internal layout followed bus practice more than railway practice: bus-type seating, narrow gangways, and the distinctive hard plastic feel that would become notorious with passengers.

From the outset the Class 142s attracted strong criticism from passengers, trade unions, and railway commentators. The four-wheel underframe gave a rough, jarring ride at speed compared to bogie-mounted conventional DMUs; the bus-derived body was too narrow for comfortable use on busy services; and the step height at station platforms caused access difficulties. They were associated in the public mind with the perceived decline of regional rail services and became a symbol of railway underfunding in the 1980s.

Despite this, the Class 142s gave over three decades of service across Northern Rail, Wales & Borders, and other operators before being withdrawn between 2019 and 2021, partly as a result of accessibility regulations that the four-wheel underframe made difficult to comply with. Several have passed to heritage railways.