95 A requirement for an audible warning if attempting to start with the TDIC switch operated was contained in the LUL technical specification for the 1996 stock.
Clause 11.12 of the technical specification related to the train door interlock cut-out switch and required:
‘Switch position ‘cut-out’ - Proving interlock with Driving Controls bypassed, Door Closed Visual not illuminated, Cab Audible Warning if motoring attempted’.
This requirement was then included in Clause 9 of LUL rolling stock standard RSE/STD/036 ‘Door control systems’ issue B, dated November 1993. Clause 9 remained in force when modifications were made to the trains to permit the introduction of ATO in 2006/07.
96 Post-incident testing showed that there was no audible warning fitted to the 1996 stock in service on the Jubilee line when the Finchley Road incident occurred.
The circumstances which led to this situation are unclear because:
- an LUL compliance check dated 12 June 1998 records the feature was fitted as specified;
- LUL has stated there was no intention to remove the functionality when the trains were converted to ATO, or at any other time; and
- LUL staff familiar with train operation before and after ATO conversion do not recall the feature being present.