SR CLASS 4DD

Conceived by the Oliver Bullied for the Southern Railway's Dartford commuter route, the two '4DD' electric multiple units were the only double-deck trains to run on the main line railway network in Britain.
The upper level seats were squeezed in between the lower level seats to ensure that the overall height of the unit would be within the clearances necessary to pass through tunnels and under bridges.
The '4DD' was somewhat unsuccessful because the upper level compartments were cramped and poorly ventilated (the upper level windows could not be opened). Also turnaround times at stations were increased because of the increased number of passengers per door. To obtain the extra seating capacity that was being sought, it was decided to lengthen trains from 8 cars to 10 instead.
However as an "experiment" they were to last in traffic from 1949 - 1971 undergoing routine maintenance and repaints with a no actual hiccups in their life, not bad for what were essentially prototypes.

Contents

Formations

Preservation

Links

Formations

'Unit Numbers' 'DMBT' 'TT' 'TT' 'DMBT'
4001 (later 4901) 13001 + 13501 + 13502 + 13002 (built September 1949)
4002 (later 4902) 13003 + 13503 + 13504 + 13004 (built October 1949)

Preservation

Driving Motor cars 13003 and 13004 survive in preservation, the former at a private location in Ashford, Kent, and the latter at the Northamptonshire Ironstone Railway Trust. One trailer car was also saved after withdrawal, but has since been scrapped.

Links

★ Southern E-Group on the 4DD

★ Bullied Double Decker Society

★ 1949 British Pathe newsreel footage of the pre-production mockup