The Airports Commission in its Final Report and supporting documents published in July 2015, considered potential options for improving capacity on the M4 motorway between junctions 2 and 4 in relation the expansion of Heathrow airport.
As part of the Government’s consideration of the Airports Commission’s work and recommendations, Highways England assessed and validated the costs and deliverability of the Commission’s strategic road proposals, which were published in October 2016 alongside Government’s announcement of its preference for a new northwest runway at Heathrow airport.
The Department recognises that future improvements to the M4 may be needed for a number of reasons to address future transport demand, including wider population and economic growth, but not solely as a result of the proposed expansion of Heathrow airport.
The Department will be considering the need for potential future improvements for the strategic road network, including the M4, as part of its long term investment planning processes for development of future Road Investment programmes.
The Government will set out details about plans for a new runway at Heathrow airport in Parliament through a draft National Policy Statement shortly. It will be subject to a full and public consultation and parliamentary scrutiny.