[7][non-primary source needed] In 2005, ahead of Crossrail's hybrid bill submission, a number of feeder routes were considered by CLRL west of Paddington and east of Liverpool Street.

In the east, routes to Abbey Wood (curtailed from Ebbsfleet to avoid conflicts with the North Kent lines) and Shenfield were selected.

[20] Though the main tunnels under central London had not yet been opened, passenger operations on the outer branches of the future Elizabeth line were transferred to TfL for inclusion in the concession – this took place over several stages beginning May 2015.

Following the practice adopted during the transfer of former Silverlink services to London Overground in 2007, TfL carried out a deep clean of stations and trains on the future Elizabeth line route, installed new ticket machines and barriers, introduced Oyster card and contactless payment, and ensured all stations were staffed.

In the central section, there are interchanges with London Underground, National Rail, and Docklands Light Railway lines.

[50] This platform height difference was criticised by the Campaign for Level Boarding who said Crossrail's "poor decision making" meant "this brand-new railway has cornered itself into perpetually offering an inaccessible service.

[51] At Maryland this is because of the prohibitive cost of extensions and the poor business case,[52] and at Manor Park it is due to the presence of a freight loop that would otherwise be cut off.

[57][58] Crossrail issued invitations to negotiate to the remaining bidders in March 2012, with submission of tenders expected between June and August.

[58] It was stipulated that bidders should offer a fleet based on technology that was "already developed", with the expectation that an "evolutionary, not revolutionary" product would help to ensure "value for money" and "[the] utmost reliability from day one".

[57][58] Siemens withdrew their rolling stock bid in July 2013, citing an increase in other business and a need to protect their "ability to deliver ... current customer commitments", which included the £1.6 billion Class 700 order for Thameslink.

[4][61] The trains have air-conditioning and are designed to be as accessible as possible, including wide aisles and gangways, dedicated areas for wheelchairs, audio and visual announcements, CCTV, and passenger intercoms connected to the driver for use in the event of emergency.

[63] Due to limited platform lengths at both Liverpool Street and Paddington National Rail stations, most Class 345 units were initially delivered as seven-car formations, then later extended to the intended nine.

[72] Following this, Alstom (new owners of the original builder Bombardier) was awarded a £370 million contract in June 2024 to build an additional ten Class 345 trains at its factory in Derby.

Operating hours were limited, as well as the service running Monday to Saturday only - allowing for further testing and software updates to take place.

[79] When through-running began in November 2022, there were two main service groups, overlapping through the core section: from Reading or Heathrow Airport to Abbey Wood; and from Paddington to Shenfield.

Likewise, some early, peak-direction, and late trains run between Liverpool Street mainline terminus and Gidea Park, bypassing Whitechapel.

Following a model similar to that used for the Docklands Light Railway and London Overground, TfL invited tenders for operation of the Elizabeth line.

Unlike other National Rail operators under the franchise control of the DfT, TfL sets fares, procures rolling stock and decides service levels.

In June 2013, TfL announced that Arriva, MTR Corporation, Keolis / Go-Ahead Group and National Express had been shortlisted to bid for the concession to operate Crossrail, which was under construction.

[83][84] Prior to the opening of the central section, the concessionaire would operate the existing railway services using the TfL Rail brand.

That stretch of line is not part of the Network Rail system but owned by Heathrow Airport Holdings, who charge TfL an additional fee for each train that uses it.

That was one-sixth of the UK's total rail journeys, and double the number the line carried during the same period one year earlier.

TfL has introduced high-speed 4G and 5G mobile coverage in the first tunnelled section of the Elizabeth line between Liverpool Street and Paddington.

This initiative, part of a broader plan to extend coverage across the entire Tube and London Overground network, aims to improve connectivity.

[104] Muyiwa Oki, RIBA president and chair of judges, said the Elizabeth line was "a triumph in architect-led collaboration" that transformed "the typical commuter chaos . . .