The single-deck Hitachi trains operated as 'M-T-M-M-T-M' sets of six carriages (two coupled sets of three carriages arranged with two motorised carriages on either end of a motorless 'trailer' carriage).
Based on a successful trial of longer Harris trailer cars built between 1967 and 1971, the Hitachi train used carriages long, up from the standard length of the earlier suburban cars [REF].