Western Rail Approach to Heathrow

The Western Rail Approach to Heathrow is a proposed rail link in Berkshire and Buckinghamshire, England, which would create an additional connection between London's Heathrow Airport and the Great Western Main Line. Beginning at Heathrow Terminal 5 station, the link would run via a tunnel to a junction east of Langley station, allowing trains to run westwards towards , and beyond. When completed, the link would improve rail connections to Heathrow from the Thames Valley as well as from South West England, South Wales and The Midlands. It would also reduce congestion at London Paddington station by removing the need for Heathrow passengers on this route to travel to Hayes and Harlington or into central London.
The rail link was first announced in 2012 with completion estimated to be in 2020. The aviation industry at Heathrow is expected to contribute to the cost, and the scheme awaits completion of a business case.
Announcements.
The project was announced by the Department of Transport in July 2012. Theresa Villiers, the rail minister at the time, included the project in the High Level Output Statement published in 2012. This stated 'The Government wishes to see a new railway link to give western rail access to Heathrow Airport' but did not commit to the scheme, making it 'subject to a satisfactory business case and the agreement of acceptable terms with the Heathrow aviation industry'.
The scheme has been supported by the Airports Commission, which included the scheme in its 2014 report on the Expansion of Heathrow Airport.
Progress.
Network Rail originally estimated that the project could be operational by 2020. In January 2017, Network Rail's estimate was 2024. Slough Borough Council has cited 'parliamentary activity' as the reason for the delay but not offered further explanation.
In May 2018, it was reported that Network Rail intended to apply for a Development Consent Order (DCO) in 2019, and that construction of the railway link would be privately financed. Before submitting the application for a DCO, Network Rail would present the final designs for the scheme in a series of public information events, which were held in early 2020.
The Department for Transport's "Rail Network Enhancements Pipeline", published in October 2019, listed the project among those in an early stage of development, awaiting a "Decision to Design" and the completion of an outline business case. In December 2020, Network Rail stated that progress had been paused by the impact of the COVID-19 pandemic on the aviation and rail industries, and that agreement was awaited on a financial contribution from Heathrow Airport Holdings. Therefore, the DCO application would be delayed until at least the winter of 2022.
Route.
The proposed route is a new railway line that would leave the Great Western Main Line between Langley and before entering a new tunnel. The tunnel (composed of two smaller tunnels) would pass under Richings Park and Colnbrook and then join existing rail lines at Heathrow Terminal 5.
Four access buildings will be built along the route to provide emergency access to the tunnels, with two additionally providing ventilation.
Realignment of the existing tracks will also be required between Langley and Iver.
The route could potentially mean closure of Mansion / Hollow Hill Lane. The effects of this closure are being investigated by Slough Borough Council.
The Western Rail Approach is, according to the Airport Expansion Consultation, designed to be "independent yet compatible" with the Heathrow expansion.
Services.
It is envisaged that there would be a service of four trains an hour from Heathrow to and . Earlier publicity also suggested there would be two trains per hour to and .
Heathrow Express have offered to run services to Reading which would stop only at Slough.
Alternative and complementary schemes.
Other schemes have been proposed to connect Heathrow Airport to the Great Western Main Line. A western link featured in the Heathrow Airtrack scheme, abandoned in 2011.
Another alternative scheme was the Windsor Link Railway, proposed in 2013 and rejected by the government in 2018, which would have provided both western and southern access to Heathrow.
A complementary scheme which could be developed at a later date, or alongside the Western Rail Approach, is the Heathrow Southern Railway, proposed since 2017 to provide links from the airport to the south and southwest.