HS4Air

HS4Air is a proposed 140km rail line from the HS2 line near Denham to Ashford International via Heathrow and Gatwick Airports. It was the similar scheme to even extend the HSR from Jurong East to Changi Airport via the city. It would form as a direct link between the HS1 and the HS2 which was scrapped in 2014 and also provide a link to Heathrow (scrapped in 2015) as well as Gatwick. A fifth of the line is to be in tunnel and could link with the Great Western Main Line. It would cost $10 billion to build and around 40% of the route is to be reusing existing network rail tracks.