Elizabeth line services hit by software issues after upgrade

Software bugs have caused disruption to Elizabeth line services and closed the line in recent weeks according to a report before Transport for London’s

Elizabeth line committee meeting to be held next week.

A recent software upgrade saw a full weekend closure over Easter introduced to permit service changes as well as increased frequency from 21st May.

Reliability dropped


However the report notes that at Stratford one change has caused issues with signalling and trains. Software updates were designed to permit removal of a temporary speed restriction with the upgrade allowing “the functionality to allow Auto Transition to be brought into use at Stratford from 11 April 2023.

“A small number of performance affecting regressions (“bugs”) were found following the release of ELR400 and are being addressed by a series of “patch” releases due from Siemens over the coming weeks.”

Elizabeth Line train at Stratford

The Elizabeth line’s Class 345 trains were made by Bombardier – who are now known as Alstom after a takeover in 2021. Bombardier had a torrid recent history with new train introductions.

Elizabeth line trains havn’t been as badly impacted as others. South Western Railways are still awaiting stock to be ready, which was due to enter service three years ago. They are sister trains to those on the Elizabeth line on the “Aventra platform. Dozens are sitting in sidings across the country in part due to software problems.

That has held up 12 “City Beam” trains moving from SWR to Southeastern – which in turn will send further Networkers to storage and likely scrap.

Delays to SWR trains have hampered stock cascades

TfL state a further software update is being rolled out in advance of service improvements from 21st May which sees services across the core increase to 24 trains per hour, and services on the Abbey Wood branch increase back to every five minutes at peak times.

Issues have also arisen since services extended beyond Paddington to Heathrow, Reading and Maidenhead. The report blames “Network Rail infrastructure in the West, where there have been a significant number of points failures, which are disrupting and take time to recover the service”.

An issue not mentioned in this report but one that is being regularly heard are poor communications when disruption does occur – which recently has been pretty often.


The meeting also sees a separate agenda item covering finance and passenger numbers:

“In the year to date (YTD) to Period 13, passenger journeys for the Elizabeth line exceeded Revised Budget by two million.

Elizabeth line at Stratford

This was due to higher than expected passenger numbers across the whole line following the start of through running. Fares income was £29m above Revised Budget as a consequence of the higher passenger numbers”.

Alongside reduced costs, “The Elizabeth line is forecast to achieve operational break even in the year 2023/24.”

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