This will increase peak frequencies from 22 to 24 trains an hour under central London and will enable full “through running”, allowing direct journeys between Shenfield in the east and Heathrow and Reading in the west.
It will conclude the staggered opening of the £20bn line, which first opened on May 24 last year, with subsequent upgrades including the delayed opening of Bond Street station in October and the start of through trains from Abbey Wood to Heathrow in November.
But the full opening is dependent on a successful final upgrade of software on the £1bn fleet of trains – and the introduction of an “automatic reverse” facility that will see empty trains “drive themselves” backwards near Paddington station to re-enter service.
The new timetable should eradicate the bulk of the seven-minute delay experienced by passengers on eastbound trains that have to wait outside Paddington to enter the central tunnels.
The “autoreverse” function enables trains taken into sidings at Westbourne Park to reverse themselves back onto the track while the driver walks through the nine carriages to the other end of the train. The driver has to switch from one end of the train to the other to drive the train back in the opposite direction.
If autoreverse cannot be implemented by May 21, it is likely to mean that some trains in the central and eastern sections will have to be cancelled and the 24 trains per hour target will not be achieved.
About 3.5m journeys a week are being made on the line – well above the 2m a week that were anticipated. By December, passenger numbers were 32m ahead of target – generating an extra £49m in fares for Transport for London.
But it has become something of a victim of its own success, with BBC London revealing on Wednesday that commuters in west London are complaining of overcrowding due to the number of Heathrow airport passengers using the line.
Howard Smith, the Elizabeth line’s director, told TfL’s Elizabeth line committee on Tuesday that problems with Network Rail infrastructure on the line’s section west of Paddington were receiving a “huge amount of focus” but were unlikely to be fully resolved until new track and signalling were installed.
He said the line was busiest on Thursdays and passenger numbers were “very healthy”, with latest figures for January showing demand was at 95 per cent of pre-Christmas levels.