No new full-length runway has been laid down in the South East of England since the 1940s. With demand growing for over fifty years, it became crucial to provide suitable infrastructure to keep pace with an expanding aviation market. At the same time, the South East of England is a congested corner of a crowded island, and many factors had to be considered before any decision.

In 2012, the independent Airports Commission was set up to assess a wide range of factors, including noise, surface transport, employment, air quality, housing and local communities, to make recommendations on the new runway.

The Airports Commission provided an appraisal framework, which set out the requirements for the noise assessment. Along with a range of noise exposure contours, the framework requested the modelling of supplementary noise metrics that were not usually calculated at that time. These were the number of noise events exceeding an outdoor maximum noise level (‘Number above’ contours)*.

To gain complete insight into the possible implications of the new runway, the Airports Commission required calculations of the monetary cost of noise exposure impacts. This meant to quantify annoyance, sleep disturbance and acute health impacts of noise on people.

The team was tasked to provide noise modelling results for over 70 separate future scenarios, each with multiple metrics. These should include the areas, populations, number of households and noise-sensitive amenities within the contours. The calculations had to be accurate as the miscalculations could affect the third runway decision and bring substantial social and economic impact.

The content of the analysis design had to be impartial, so the client’s specialist traffic forecasting consultancy provided traffic volume data, and the sponsor organisations provided the route design information for each proposal. The ERCD used their expertise to create data to model new, quieter aircraft designs to reflect future scenarios.

The team designed and quality-assured new computational processes to compute the supplementary metrics and developed a methodology that had not been used before to calculate the monetary cost of noise exposure impacts.

To ensure accuracy, ERCD established working practices and common modelling assumptions, including average temperature, atmospheric pressures, and ground types. It also implemented rigorous quality assurance procedures.

ERCD produced results for nearly 350 separate scenarios and noise metrics combinations, requiring over 1,800 different model runs. Monetised impact data were provided, which allowed economic, operational, social, and environmental factors to be considered on an equitable basis. A newly developed methodology to quantify acute health impacts of aircraft noise was incorporated in the United Kingdom Department for Transport (UK DfT) WebTAG** assessment guidance. The aviation noise analysis by ERCD was published in 2015 and helped the Airports Commission decide on three proposals for the South East of England’s runway.