Slam-door train

Connex South Eastern Class 423 at Waterloo East in February 2003
c2c Class 312 at Shoeburyness in March 2003

A slam-door train or slammer is a set of diesel multiple units (DMUs) or electric multiple units (EMUs) that were designed before the introduction of automatic doors on railway carriages in the United Kingdom and other countries, which feature manually operated doors. The name came about because of the characteristic noise made by the passengers slamming the doors closed when the train was about to depart.

Some slam-door train designs featured doors that could only be opened from the outside, so passengers had to lean out of the window to reach the outside door handle.

Slam-door trains had many more doors than newer trains (which tend to have only two sets of doors per coach); some designs featured a door for every individual seating bay. Some units had individual compartments, each with its own door and no access to any other part of the train; however, these were unpopular due to security concerns and the lack of access to toilets for longer journeys and many were later converted to standard corridor saloon design. The phase out was speeded up after the Murder of Deborah Linsley in such an individual compartment in 1988.

The term "slam-door" could also refer to locomotive-hauled railway coaches that did not have automatic doors, but this usage is less common. The term "slam-door train" generally applied to Mark 1 and Mark 2 DMUs and EMUs.