There are currently numerous controversies around the world in regards to airport expansion, where local residents are opposed to new runways or changes in the hours of operation. The most famous example is probably Heathrow airport, where it took decades to finally approve a plan to add a third runway.

But why aren't airports built in a way where future expansion is possible? E.g. why wasn't an area 5 kilometers around Heathrow reserved for new terminals and runways, even if it wasn't clear if they're ever going to be required?

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    $\begingroup$ Land is expensive. $\endgroup$ Nov 1, 2019 at 20:30
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    $\begingroup$ So why not just have a law such as eminent domain and take it when you need it? The property terms you suggest would make land worthless, nobody in their right mind would buy property with that kind of vacate term. In England this is called "compulsory purchase". $\endgroup$
    – Ron Beyer
    Nov 1, 2019 at 20:42
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    $\begingroup$ KDEN absolutely was built with the possibility of future expansion in mind. But, it had to be built far, far away from town in order to do so. $\endgroup$
    – Ralph J
    Nov 2, 2019 at 0:35
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    $\begingroup$ @Ron Beyer: Because the public tends to object when you do things like that, which means that you (or your elected bosses) don't get re-elected. $\endgroup$
    – jamesqf
    Nov 2, 2019 at 2:39
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    $\begingroup$ Even if you found someone willing to take the deal, no half-sensible lender will write mortgages against property where there's an agreement to vacate at any time if the land is needed. You might be interested in avigation easements though, which permit overflights, prevent property owners near the airport from building tall structures that would interfere with airport operations, require airport-compatible land uses, and usually have some kind of agreement not to sue the airport over noise, perhaps offered in exchange for cash and/or noise-proofing services. $\endgroup$ Nov 2, 2019 at 5:47

1 Answer 1


Many European airports are built relatively close to the cities they serve. Airports in the US are (in general) further away, where an expansion is easier to do, e.g. Denver International Airport:

The distant location was chosen to avoid aircraft noise affecting developed areas, to accommodate a generous runway layout that would not be compromised by blizzards, and to allow for future expansion.

Heathrow on the other hand is old. It has such a long history that it has its own Wikipedia article (which ironically starts in 1410!). It started as a small airfield in the 1930s and it was in a very rural area at the time:

The land was at the time used for market gardening and wheat growing.

It was then greatly expanded as a military airport during World War II. After the war, the airport was turned into a civilian airport. The original runway layout way quite different compared to today, as the following image from the 1950s shows:

Heathrow in 1950s
(image source: Wikimedia)

This image still shows the rural surroundings. But London expanded further and further and eventually the airport was fully surrounded:

Heathrow today
(Google Maps)

Why was the land not reserved?

Because land in London is extremely valuable. The time after World War II saw the greatest expansion of London (size wise, not population wise):

The population peaked in 1940 at around 8.5 million, before declining and then rising recently to just over 8 million. Despite the decline and the devastation caused by the second world war, the 20th century saw the largest urban expansion in London’s history.

(The Guardian)

At the same time, other airports were expanded to serve the Greater London area: Gatwick was expanded during the 1950s, Luton in the 1960s and Stansted was converted to a civilian airport in 1966. With all of these airports available, there was no need to anticipate a large expansion of Heathrow. The land was much more valuable as an urban area.


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