Work has begun on the Stockley Interchange in west London which will allow Crossrail services to operate to and from Heathrow.

Network Rail, on behalf of Crossrail, will build a new single track viaduct for all trains from Heathrow towards London. Work is due to complete in 2017. Existing train services to Heathrow will continue to run throughout.

The current junction at Stockley is used by Heathrow Connect in both directions and Heathrow Express in the London direction. The viaduct will start on the western side of the existing airport lines and cross over all of the tracks in the railway corridor, turning eastwards and continuing on the northern side of the railway tracks.

The viaduct will then widen and a junction for Crossrail and Heathrow Express services will be installed. This junction will allow Heathrow Express services to cross above the slow lines and descend to main line track as at present.

Crossrail services will remain on the northern side, descend on a second ramp and run on a dedicated track which will then connect with the existing up slow line via a new junction constructed just before Hayes & Harlington station.