New Civil Engineer understands that the government is poised to give the go ahead to additional runway capacity at Heathrow and Gatwick.

It is believed that the announcement will be made on 18 October, with government giving the green light to a third runway at Heathrow immediately and also allowing Gatwick to expand with a second runway within the next five years.

Gatwick’s 30-year agreement with local authorities not to expand is due to expire in 2019.

It is also understood that government will urge Birmingham airport to advance its proposals for an additional runway.

The decision to encourage all three airports to expand comes after increasing demand in the London area over the last three years has far exceeded predictions used by Sir Howard Davies’ Airport Commission.

Davies’ published his independent report setting out its recommendations for expanding aviation capacity in the UK in 2015. To meet the projected growth, it said that a new runway was required by 2030 and gave a new northwest runway at Heathrow Airport as the preferred option.

This, however, was based on a predicted growth in passenger numbers from a Department for Transport (DfT) report. This 2013 report used passenger figures from 2010 through to 2012 which saw airport usage at a seven-year low in 2010 after the financial crash in 2008. A slow recovery in 2011 and 2012 may have influenced a low passenger estimate in 2030.

In the report, Heathrow was predicted to rise from 70M passengers per annum (ppa) in 2011 to 85Mppa by 2030. Similarly at Gatwick it predicted a rise in numbers from 34Mppa in 2011 to 42Mppa by 2030. Overall London was predicted to rise from 135M ppa to 184M ppa across Heathrow, Gatwick, Stansted, Luton and London City airport.

However, since 2013, actual passenger numbers have increased at a rate far above this.

In 2015 the total number of passengers at Heathrow was 75M; however, without expansion it is operating at near capacity and will therefore not see a rise in passenger numbers. At Gatwick, the actual number of passengers was 41M and at growth predictions based on data from 2013 to 2015, it is predicted to surpass the 2030 estimate in 2016.

Overall, it has been predicted that if the current growth continues, London would hit the 2030 passenger number of 184M in 2019, 11 years ahead of the forecast.

Birmingham airport was the only non-London based airport to not be entirely discounted by the Airport Commission’s report. The interim report stated that: “It would offer the largest catchment of people within two hours of the airport of all options. This is largely dependent on the journey time assumptions of HS2, which also makes the London airport system easier to access for passengers from Birmingham’s core aviation market.”

However, speaking at New Civil Engineer’s Airports conference earlier this year, UK Civil Aviation Authority (CAA) chief executive Andrew Haines said that even if either Heathrow or Gatwick was given permission to expand, they could face challenges securing the required investors.

He said that because the project did not have government assurance, it would not be bailed out should costs rise and investors may find it difficult to take on the risk.

“There is no track record of regulation being applied to something of this size,” he said.

Haines explained that it was genuinely unprecedented for there to be a major multi-billion pound infrastructure investment of this scale with absolutely no government guarantee or assistance. He said that the nearest project in terms of scale of investment is Hinkley Point C nuclear power station, and even that comes with government guarantee.