From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Map of the proposed HS4Air line in Southern England
OwnerNetwork Rail
LocaleSouth East England
Ashford International
Typehigh speed railway
SystemNational Rail
Planned openingLate 2020s (Late 2020s)[2]
Line length87 miles (140 km)
Number of tracksDouble track
Track gauge4 ft 8 12 in (1,435 mm) standard gauge
Loading gaugeGC
Electrification25 kV AC overhead

HS4Air was a proposal for a 140-kilometre (87 mi) high-speed railway line in the United Kingdom, put forward in 2018 by a British engineering consultancy, Expedition Engineering.[3]

The proposed line would have connected the planned High Speed 2 line to the High Speed 1 line via a high-speed route running south of London, and would form a direct rail link between Heathrow and Gatwick airports. The proposal was rejected by government in December 2018 and will not go ahead.[4]


The first high-speed railway line to be built in the United Kingdom was High Speed 1 (HS1), the route connecting London to the Channel Tunnel, which opened 2003−2007.[5] A second high-speed line named High Speed 2 (HS2), which will initially run between London and Birmingham, is planned to open in 2026.[6]

A proposal to build a direct connection between HS1 and HS2 in central London was dropped from HS2 construction plans in 2014 due to cost and the impact on the London district of Camden.[7][8] The HS2 plans also included a connection to Heathrow Airport at Heathrow Hub railway station, but that link was dropped in 2015.[9]

A number of other schemes have been considered to create a rail link between Heathrow and Gatwick airports, collectively dubbed "Heathwick".[10]

Planned route[edit]

The proposed line would leave the HS2 line at a junction near Denham in Buckinghamshire, and then run on a route curving south-west of London, partly parallel to the M25 motorway, with stations at Heathrow Airport and Gatwick Airport. It would then head eastwards across Kent using the existing upgraded South Eastern main line via Tonbridge to join HS1 at a junction at Ashford International. The link between HS1 and HS2 would allow high-speed trains to travel directly between regional cities in Great Britain and destinations in Continental Europe.[11]

A fifth of the line was planned to be in tunnel in order to mitigate the environmental impact on sensitive rural areas such as the North Downs.[11] It was also proposed to construct a link with the Great Western Main Line.[12][13][3] It would cost £10 billion to build and around 40% of the route would reuse existing tracks; the proposals included upgrades at Ashford International and Tonbridge stations.[1]

The scheme envisaged a 15-minute transfer time between Heathrow and Gatwick, allowing the two airports to operate jointly as an airline hub. Fast connections between the airports and Birmingham, Manchester and Cardiff were also proposed, and the proponents of the scheme claimed that it would alleviate pressure on transport within London by reducing the need for air passengers to travel through the city.[12][14]

The scheme was also linked to proposals to re-open Manston Airport in Kent, which could be connected to the line via Canterbury West.[2]

Government response[edit]

Expedition Engineering's proposals were submitted to the Department for Transport (DfT) at the end of July 2018, as part of the Government's plans to encourage private investment.[15][16] The HS4Air scheme was rejected by Government in December 2018 because the DfT did not consider that Expedition Engineering's proposals were "financially credible without government support", and anticipated public opposition to building the route across green belt land.[4][17]

See also[edit]


  1. ^ a b Chessum, Victoria (23 July 2018). "HS4Air reveals two Kent stations will be upgraded as part of huge plans to connect with Heathrow and Gatwick". KentLive. Retrieved 24 July 2018.
  2. ^ a b Couchman, Adele (12 March 2018). "Bosses prepared to connect Manston in multi-billion pound high speed rail link". KentLive. Archived from the original on 22 July 2018. Retrieved 22 July 2018.
  3. ^ a b Tute, Ryan (7 March 2018). "Firm pitches "an M25 for high-speed trains" to pass through Heathrow and Gatwick". Infrastructure Intelligence. Archived from the original on 30 July 2018. Retrieved 12 March 2018.
  4. ^ a b Smale, Katherine. "HS4Air plan to link Heathrow and Gatwick rejected". New Civil Engineer. Archived from the original on 11 December 2018. Retrieved 11 December 2018.
  5. ^ The completion and sale of High Speed 1: Department for Transport. National Audit Office/The Stationery Office. 2012. ISBN 9780102975482. Retrieved 30 July 2018.
  6. ^ High Speed 2: a review of early programme preparation, Department for Transport. National Audit Office/The Stationery Office. 2013. pp. 14–15. ISBN 9780102981421. Retrieved 30 July 2018.
  7. ^ "HS2 boss calls for rail link threatening Camden markets to be axed". Ham & High. 17 March 2014. Retrieved 12 May 2014.
  8. ^ "Government to scrap HS2 link with HS1". www.railtechnologymagazine.com. 25 March 2014. Retrieved 30 July 2018.
  9. ^ "Heathrow HS2 spur plans dropped". BBC News. 10 March 2015. Retrieved 30 July 2018.
  10. ^ "Ministers mull airports rail link". BBC News. 8 October 2011. Retrieved 30 July 2018.
  11. ^ a b "HS4Air". Expedition Engineering. Archived from the original on 30 July 2018. Retrieved 30 July 2018.
  12. ^ a b Chessum, Victoria (8 March 2018). "New High Speed rail line will connect Kent with major airports in under an hour". kentlive.news. Retrieved 12 March 2018.
  13. ^ "From Kent to Gatwick in 25 minutes..." kentonline.co.uk. Retrieved 12 March 2018.
  14. ^ Nolan, Tara. "HS4Air: The UK needs a strategic plan for its transport infrastructure". Global Railway Review.
  15. ^ Paton, Graeme (20 July 2018). "M25-style railway takes you from Gatwick to Heathrow in 15 mins". The Times. ISSN 0140-0460. Retrieved 20 July 2018.
  16. ^ Grafton-Green, Patrick (21 July 2018). "New M25-style railway takes you from Gatwick to Heathrow in 15 minutes". Evening Standard. Archived from the original on 22 July 2018. Retrieved 22 July 2018.
  17. ^ Daniel, Alex (11 December 2018). "£10bn train route linking Heathrow and Gatwick airports rejected". www.cityam.com. Retrieved 19 December 2018.