Following continued reactions to its 3rd runway expansion plans, Heathrow presented an alternative proposal, with a circular runway.

Heathrow Airport has discussed ways to expand its operations for well over a decade now. While it is already the busiest airport in the United Kingdom, Heathrow has long exceeded its optimum capacity. To expand, the airport needs more parking slots for its aircraft, and a means to increase aircraft movements. In short, Heathrow needs more space, including a new runway – or a circular one.

The idea of airports with circular runways is a persistent one, Heathrow being only its latest example. Not only are such runways impervious to variations in wind direction, they also make more efficient use of space. With such a layout, the airport could allocate a far greater amount of centralized space for terminals and aircraft parking. Pictures show what such a plan would look like, in practice.

Heathrow’s circular runway would have a diameter of 3.5 kilometres (~2.2 miles). This makes it 11km in circumference, although measured at its centreline, its actual length would be around 9.75km (6 miles). This makes it between two and three times as long as most conventional runways. And this means that such a circular runway could replace Heathrow’s existing runways, and increase capacity!

Circular Runway Optimizing Heathrow’s Space

Unfortunately, the pictures also show that it will still be necessary to occupy quite a bit of new land. However, the circular runway setup also means that Heathrow will give up a lot of land, too. And this should make compensation to land owners somewhat easier. Also, the new plan means that it will be unnecessary to cross the M25 motorway. This was a central element of the previously-existing plan. This alone will bring considerable savings to the project. However, there will be plenty of tunnels needed, for access to the airport itself.

One possible problem with circular runways (also called ‘endless runways’) is the use of Instrument Landing Systems (ILS). Arranging multiple such systems around a circular runway would create problems and limit the effectiveness of the runway. However, newer technologies with GPS and even ground mapping or terrain recognition should alleviate all such concerns, soon. The Airbus ATTOL programme could help a lot, in this regard.

Another possible concern is that the curved runway surface could present risks for larger aircraft, with four engines. But with production of the A380 and 747 soon at an end, these problems should go away. Also, Heathrow authorities point out that a circular runway makes crosswind landings a thing of the past. And that, in turn, means that engine strikes (or ‘pod’ strikes) become much less likely!

Environmental And Efficiency Gains

A circular runway could potentially make Heathrow more environmentally friendly. This is because a centralized terminal layout minimizes the need for taxiing. And in low-wind scenarios, there would be further fuel savings from simultaneous use of the runway for multiple landings and take-offs. This would minimize the time aircraft will spend in holding patterns!

Speaking of traffic, it is true that multiple possible approaches and take-offs, would likely complicate airspace over London. But apparently it generally isn’t very busy, so this would be an acceptable trade-off. Other trade-offs of the circular runway setup, involve the relocation of cargo facilities and the still-new Terminal 5. Heathrow airport authorities believe that increased revenue from new aircraft slots will more than make up for this redevelopment.

Unfortunately, there are some early reports of negative reactions to this plan, coming from plane spotters. The unpredictable positions of aircraft take-offs and landings, plus the banked nature of the circular runways, could seriously hinder plane-spotting opportunities around Heathrow Airport.

For more details, go to the source, here.

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Some more information on these runways: