Documents reveal Heathrow runway transport links could cost taxpayer £18bn and worsen pollution

The cost to the taxpayer of upgrading transport links to deal with a third runway at Heathrow could add up to £18.4bn – according to new documents seen by Unearthed.

The documents also revealed that plans for the third runway could exacerbate London’s air pollution concerns – due to increased traffic.

The internal Transport for London (TfL) spreadsheets and slideshows were released following an investigation by mobility and environmental campaigners.

TfL has published cost estimates in the past but the files reveal the first detailed analysis by London’s transport regulator of the cost of a third runway.

The Airports Commission, set up by ministers to examine Heathrow, put the figure for surface transport costs at £4.2bn though a figure of £5.7 billion has also been widely reported.

Read the documents

Traffic costs 

However the TfL analysis suggests the Commission’s report fails to take into account the costs of key rail schemes, extra buses, additional operational spending and road traffic management.


Both sets of estimates include the costs of major road schemes such as putting part of the M25 in a tunnel and widening sections of the M4.

However the Airport Commission’s estimates overlooked the cost of additional buses, road traffic management, and major rail improvements such as an upgraded Great Western Main Line, a new rail link through Staines, and an extension to Crossrail 2 running from Teddington to Heathrow.

Many of these projects were in the Commission’s assumptions – but without any additional funding.


Air pollution

A third runway at Heathrow is expected to put an extra 30 million passengers on the London transport network every year – TfL argues the extra measures are needed to manage traffic and prevent worsening air pollution.


In one slide TfL warn that under the Commission’s own projections the Bath Road would have the highest Nitrogen dioxide concentrations in London – delaying already tardy efforts to meet EU air pollution rules.

The news will reignite the longstanding controversy over who will pay for the road and rail works needed to absorb the extra traffic from a new runway.

The government has made it clear that it expects aviation expansion promoters to cover any surface access costs, but Heathrow bosses have said they are not willing to pay anything above £1.1 billion.

Not all the slides make that much sense
Not all the slides make that much sense