Should London have a new airport? While common sense suggests adding extra runways at Heathrow, Gatwick and Stansted is the simplest way to provide much-needed extra airport capacity for Britain’s capital, there are strong voices in favour of closing Heathrow and building a new airport to serve the city.
The clamour is led by the London mayor, Boris Johnson – so much so that the proposal to build a new airport in the Thames estuary has been dubbed “Boris Island”. Johnson is an ambitious politician – and the decisions to go ahead with major infrastructure projects are often political. So if Johnson were to achieve his ambition of building a new airport for London, what would the project involve?
A disastrous concept?
It’s not a decision that should be taken lightly. And there are examples from the recent past that demonstrate just how complex and costly such a project would be. The growth of Asian megacities means old airports are soon rendered incapable of handling the traffic that the cities generate. Hong Kong and South Korea’s capital Seoul have both built new airports on reclaimed land, giving us a good idea of how difficult a project Boris Island might be.
Hong Kong’s need for a new airport was acute. The old Kai Tak airport was at full capacity, with just one runway. And anybody who experienced the astonishing dog-leg approach that pilots had to contend with will testify that the airport would have been unsustainable in the age of the A380.
Hong Kong International Airport is built on 75% reclaimed land
Building the new Hong Kong International Airport (HKIA) at Chek Lap Kok was one of the biggest construction projects in the world. It cost more than US$20 billion and took six years to build, opening in July 1998. The project involved 12.48 square kilometres of reclaimed land between the two islands of Chek Lap Kok and Lam Chau – the airport increased the land area of Hong Kong by 1%. Around 25% of the site was existing land; 75% was reclaimed from the sea.
It was initially built with two runways but there is now a need to expand the airport further, as demand has increased dramatically over the past decade and the mix of aircraft has changed. HKIA’s original design was based on 1992 forecasts that by 2040 HKIA would handle 87 million passengers, 9 million tonnes of cargo and 380,000 aircraft movements, the majority of which would be from origin and destination traffic.
But HKIA has evolved as a major hub airport, so it now serves a significant volume of transfer/transit traffic and a growing number of narrowbody aircraft flying to destinations in China, not just long-haul widebody flights. Current forecasts suggest that by 2030, HKIA will handle 97 million passengers, 8.9 million tonnes of cargo and 602,000 flight movements.
Airport Authority Hong Kong
Expansion plans at HKIA will see a third runway and a new terminal
A third runway is now planned, together with a new terminal, and that means more land beyond the existing airport boundary will have to be reclaimed. It won’t come cheap – it will cost an estimated US$17.5 billion – almost as much as HKIA’s initial development. And the project presents new challenges – the new runway will sit on a contaminated mud bank, which means simply dredging the site is not an option.
Dredged reclamation was used in the construction of the existing airport platform. But this requires removal of existing soft marine sediments, and that would disturb the contaminated mud. So, various non-dredging methods will be used instead. In the contaminated areas, a technique called Deep Cement Mixing (DCM) is being proposed, whereby cement is injected and mixed into columns in the soft mud. A layer of sand is then used to cap the contaminated sediment, which allows land formation while locking in the toxins.
In non-contaminated areas, a different technique will be used. This involves dropping a layer of landfill over the marine mud, and using vertical wick drains to remove the water from it. This method offers significant environmental improvements: less waste generation, less impact on water quality and lower marine ecology impact.
The 34km rail line from Hong Kong to HKIA cost an estimated $4.3bn
HKIA required another major infrastructure project. The new airport is much further from Hong Kong than the old one, so a rail link to Kowloon and Hong Kong Island was needed. This 34km line was opened in 1998, and cost an estimated US$4.3 billion. The project was built mostly on reclaimed land, and 3.5 million square metres of major property developments at five sites around the stations helped fund the plan. It involved bridges to connect the airport with the mainland, while a tunnel takes the line through Kowloon and over to Hong Kong Island.
South Korea’s Incheon airport is expanding – this new terminal will be open by 2017
South Korea’s Incheon airport also required major connection infrastructure. Like Hong Kong, the city of Seoul had outgrown the existing Gimpo airport, and the decision was taken to build on reclaimed land between Yeongjong and Yongyu islands, close to the town of Incheon, 48km west of Seoul.
Two for one
The two islands were originally separated by sea, and the project joined them together. A road and rail causeway connects the airport to the mainland. Express trains take just 43 minutes to reach central Seoul: the 61km line also connects Incheon and Gimpo airports.
Incheon International Airport
Incheon is built between two islands – the green area on the left is the site of the fourth runway
Incheon airport opened in 2001 at a cost of around US$5.5 billion – relatively cheap compared with Hong Kong – and a subsequent expansion programme was completed in 2008, adding a third parallel runway and a new cargo terminal. Incheon currently has an annual capacity of 410,000 flights, 44 million passengers and 4.5 million tonnes of cargo.
The next step
A third phase, due to be completed by 2017, involves a further spend of US$3.7 billion on a second passenger terminal and more freight capacity, taking capacity to 62 million passengers and 5.8 million tonnes of cargo a year. And further expansion, from 2017 to 2020, will add a fourth parallel runway on land already reclaimed, and will take passenger capacity to 100 million, making Incheon one of the world’s top 10 airports.
Foster + Partners
Boris Island would see London’s main airport relocated to the Thames estuary
Building Boris Island rather than expanding Heathrow would be achievable – but it would be expensive. Estimates of £30 billion in public subsidy do not seem far wide of the mark. The HS1 rail link between London St Pancras and the Channel Tunnel passes near to the proposed Isle of Grain site, but a link would be required, as would new roads.
Additional problems come from migratory geese that nest in the Thames estuary, bringing a very high risk of bird strikes. And the area is susceptible to fog, which might cause insurmountable problems if aircraft are diverted. And perhaps crucially, it’s not supported by UK businesses. The CBI says 202 of the top 300 companies in Britain have head offices within 40km of Heathrow, including many in the Thames Valley corridor – so Boris Island is simply on the wrong side of the city.
It’s unlikely to happen, but experiences in Seoul and Hong Kong prove that the project is possible – at a price.