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| Central and Elizabeth line trains at Ealing Broadway |
The Elizabeth line represents one of the most significant recent developments in London’s transport network, yet it often prompts questions about its relationship to the London Underground (LU) and why it is not classified as a Tube line. Transport for London (TfL) has addressed this on multiple occasions on X (formerly known as Twitter), emphasising clear distinctions between the two.
According to TfL tweets from recent years, where they responded to various users on why the Elizabeth line is not part of the London Underground:
"It's because the Elizabeth line isn't part of LU (i.e. it's not a Tube line). "Elizabeth line" is the name of the mode and is equivalent to London Underground, London Overground, DLR, etc, whereas Victoria, Central, etc refer to specific routes within LU."
https://x.com/TfL/status/1527689997352161283
"The Elizabeth line is an addition to the transport network and it's not a Tube line.
The distinction is that the ‘Elizabeth line’ is in itself the name of the new railway & the route it operates on. In contrast, the London Underground is the name of a separate mode of transport which operates individually named lines/routes. The Elizabeth line will always have the word “line” included in all signage and references to the line. I hope you enjoy your journeys on it when you travel!"
https://x.com/TfL/status/1528681777077927936
https://x.com/TfL/status/1528681845562523650
"the Elizabeth Line it isn't considered a Tube line because it uses the National rail network and has bigger trains. Thanks"
https://x.com/TfL/status/1732540283072499982
"The Elizabeth Line is not a tube line, but it uses the tube tunnels and Network Rail Lines, so it is still apart of the TfL services."
https://x.com/TfL/status/1598095442750873602
Briefly, as TfL mentioned the Elizabeth line sharing Network Rail infrastructure, it's worth pointing out that the London Underground's Bakerloo line shares tracks with London Overground mainline services on the Watford DC line between Queen's Park and Harrow & Wealdstone.
Origins and Development of the Elizabeth Line
The concept behind what became the Elizabeth line has roots extending back to the late 1980s and early 1990s, with a joint venture between Network SouthEast and London Underground. Their Central London Rail Study in 1989 laid the groundwork for exploring east–west cross-London rail links, which ultimately contributed to the Crossrail idea. In 1991, a private bill was submitted by London Underground and British Rail for a new east–west tunnel, but it was rejected by Parliament in 1994.#Throwback: In 1991, a @Crossrail information leaflet proposed the opening of the service in year 1999.
— CLondoner92 (@CLondoner92) May 24, 2022
At the time, the #Crossrail project in the 1990s was a joint venture between London Underground and Network SouthEast.https://t.co/Zy3nY1Fwxy pic.twitter.com/ONiQoiJMCR
Subsequently, Cross London Rail Links Ltd (CLRL), a joint venture between TfL and the Strategic Rail Authority, took the project forward from 2001, developing the business case and plans. TfL Rail began operations on 31 May 2015 when TfL took over commuter services between Liverpool Street and Shenfield from Abellio Greater Anglia. These services were transitional as the longer Crossrail project advanced. TfL Rail later incorporated services between Paddington and Heathrow and Reading (2018–2019), modernising stations and introducing Class 345 trains from 2017. When the central Crossrail tunnel opened in May 2022, TfL Rail merged fully into the Elizabeth line, dropping the interim name.
The line was renamed “Elizabeth line” in February 2016 to honour Her Majesty Queen Elizabeth II, recognising her long reign and historic connection to London transport. The name reflects a tradition of royal links to the city’s transport system and highlights the line’s massive investment to transform travel across London, creating thousands of jobs and new homes, and increasing rail capacity with modern stations and trains across the route from Reading and Heathrow to Shenfield and Abbey Wood.
Technical and Operational Comparisons: Underground vs Elizabeth Line
There are key differences between the London Underground (Tube) and the Elizabeth line, which explain why TfL treats them as distinct transport modes.
Type and Operation:
The London Underground is a deep-level metro system with 272 stations, using mostly shorter trains to provide frequent high-capacity services across London on dedicated underground tracks. In contrast, the Elizabeth line is a suburban heavy rail service operated primarily above ground with a 21-kilometre (13-mile) central tunnel beneath central London. It operates longer trains, specifically 9-car Class 345 trains, similar to commuter rail services. The Elizabeth line is run by GTS Rail under TfL but is technically not a Tube line.
Routes and Coverage:
The Underground comprises 11 lines covering over 250 kilometres (155 miles) of track, serving central and outer London. The Elizabeth line runs east–west over 118 kilometres (73 miles) from Reading and Heathrow in the west to Shenfield and Abbey Wood in the east, serving 41 stations and linking major mainline and Underground hubs.
Trains and Capacity:
Tube trains, such as the S8 Stock used on the Metropolitan line, are typically eight cars long and measure approximately 133.68 metres (438 feet 7 inches) in length. These trains are designed to navigate the tight curves and tunnels of the Underground network and have a width of about 2.82 to 2.92 metres (9 feet 3 inches to 9 feet 7 inches). Despite their modern design, some older rolling stock is still in use on lines such as the Bakerloo line.
The Elizabeth line trains are longer nine-car Class 345 trains, measuring over 200 metres (656 feet) in length. They are designed for longer suburban journeys and airport connections, offering air conditioning throughout, walk-through carriages, and dedicated luggage spaces. The Class 345 trains provide greater speed and comfort, suited to travel over longer distances across London and beyond.
Accessibility and Modern Features:
Only about 34% of Underground stations offer step-free access, with many older stations lacking full accessibility features. By contrast, the Elizabeth line provides step-free access at all its stations and uses modern signalling technology (CBTC), enabling up to 24 trains per hour through the central core.
Speed and Frequency:
Tube trains run very frequently, in some central areas every 2 to 3 minutes, but speeds are limited due to tunnels and station spacing. Elizabeth line trains have a top frequency of 24 trains per hour in the core, running at faster speeds on outer sections and with less frequent service at terminal stations like Heathrow.
Passenger Experience:
The Tube is iconic, but it can often be crowded, noisy, and uncomfortably hot, particularly on the older lines. In contrast, the Elizabeth line offers a more spacious and quieter environment, designed with passenger comfort in mind. Its modern trains are well-suited to longer journeys and those carrying luggage, and they feature USB charging ports, clear and colourful digital displays providing route information, and live TfL service updates to help passengers stay informed throughout their journey.
Operational Management
MTR, a Hong Kong-based rail operator, won the contract to operate Crossrail services from May 2015, initially running TfL Rail services between Liverpool Street and Shenfield and later expanding to Heathrow and Reading before the opening of the central tunnel. MTR consistently maintained punctuality and customer satisfaction until the contract expired in May 2025.
Since May 2025, GTS Rail Operations Limited—a joint venture between Go-Ahead, Tokyo Metro, and Sumitomo—has managed the Elizabeth line. GTS now handles over 700,000 passengers daily, focusing on safety, reliability, and service expansion, especially towards the new Old Oak Common station. TfL retains overall control of fares, marketing, and investment decisions.
The Crossrail Central Operating Section (CCOS) forms the central part of the Elizabeth line, running between Paddington and Abbey Wood. This section includes the new tunnels and stations in central London and is owned by TfL. The infrastructure was constructed and delivered by Crossrail Limited, a wholly owned subsidiary of TfL, to serve as the core link connecting the east and west branches of the Elizabeth line through central London.
The CCOS is designated as a standalone railway infrastructure and TfL, as its infrastructure manager, is regulated by the Office of Rail and Road (ORR). This ensures that the central section meets safety and operational standards while being integrated seamlessly into the wider Elizabeth line network, providing a continuous and reliable cross-London service.
TfL’s Structure and Integration
TfL operates its extensive transport portfolio through several subsidiaries to deliver efficient services across rail, metro, and buses. Key subsidiaries include:
Transport Trading Limited: the holding company owning TfL’s operating companies, including London Underground Limited.
London Transport Insurance (Guernsey) Limited: provides insurance services to TfL and its subsidiaries.
TfL Trustee Company Limited: manages TfL’s pension fund.
London Underground Limited runs the Tube network, while Rail for London Limited manages passenger services like the Elizabeth line. While these subsidiaries handle day-to-day operations, TfL maintains full oversight of fare structures, service standards, and capital projects, ensuring an integrated transport system for London.
The London Overground network is operated by Arriva Rail London under a concession agreement with Transport for London. Arriva Rail London, a subsidiary of Arriva UK Trains, has held this concession since November 2016 and recently secured a contract extension until May 2026. As a concession operator, Arriva Rail London works closely with TfL to deliver efficient and reliable rail services, implementing improvements such as increased capacity and new trains, while maintaining high service standards for over 400,000 daily passengers.
Conclusion
In essence, the Elizabeth line is a modern suburban railway designed to complement the London Underground, with longer trains, higher capacity, and enhanced passenger comfort for longer journeys and airport travel. The London Underground remains a classic metro system optimised for frequent, high-capacity service in often confined urban tunnel environments. Both systems are integral parts of London’s transport landscape but are structured differently to best serve distinct travel needs and operational requirements.
I would like to extend an invite for you to follow me on X (formerly Twitter) for transport-related updates. You can find me by searching for @CLondoner92 or by clicking on the direct link to my X page here. I am also present on BlueSky and Mastodon. I look forward to connecting with you on these platforms. Thank you for your support.
Image attribution
By Sunil060902 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=119788395
