The Mathematics and Physics of Runway Capacity and Utilisation.

-Like London's Heathrow, Manchester, Hong Kong, Singapore and others ,Dubai Airport has two parallel  runways.

-For 90 days from 1st May until the end of July Dubai will be operating with only one of its two runways open at any time. Runway resurfacing and taxiway additions and improvements are now essential so the airport has simultaneously taken all its bulls by the horns.

-As result movements have been reduced by around 25% throughout the period.

-Prior to May 1st inbound holding delays of up to 40 mins were common especially in the peaks Departures were also frequently held awaiting slots.

-One might have expected that with runways reduced by 50% and movements by only 25% things would have got worse.

-In fact they have got noticeably better.

There is a potentially rich seam of study here for physicists, statisticians and others. Somewhere in the mix must be critical points up to which everything goes reasonably well and beyond which it suddenly goes over a cliff and collapses in a heap. The Gatwick people whose achievements with a single runway are legendary may have a view. So would those who controlled Hong Kong's Kai Tak with the added complication of the famous late sharp right hand turn and the frequent nailbiting gamesaver "Expect late clearance to land".

There is another interesting issue here about airport design. Dubai's layout with its main terminal to the west of both runways requires much crossing of the western runway by traffic using the eastern. In theory this does not reduce runway movements/capacity as the crossing aircraft do so in the unusable gaps immediately after the landing or departing aircraft has passed across their nose. The same applies at Heathrow where aircraft from Terminal 4 or the Cargo or VIP areas using the northern runway have to cross the southern one to do so. The home and other frequent user carriers may normally be able to confidently accomplish the crossing in the time allowed. Others may be much less quick off the mark (controllers will know who they are but consistency is never total) and require more of a gap before the next movement on the runway to avoid the further capacity- reducing complication of people having to hit the go-round or abandon takeoff buttons.

In all this ,- and notably the debate about a possible 3rd or even 4th runway at Heathrow,- the location of the terminal(s) is crucial. On a two runway airport the terminal complex needs to be between them. Put a terminal north or south of the 2 runways Heathrows T4 style and you've got a time wasting problem. Add a third runway and another terminal between runways 2 and 3 is required. All three runways should not be seen as serving both terminals unless the third is so far offset from the previous two that a taxiway can be built from it well clear of the thresholds of the other two enabling access to the original terminal area without crossing or interfering with the intervening live runways. It's possible but would require a lot of time and money spent on additional  taxiing.

By the same token even at the present Heathrow where every additional slot is worth millions, all aircraft to and from the southern side of the airport should routinely be restricted to the southern runway,- and always have been. In the way is the endless debate about and refusal to accept or impose mixed mode operations as a matter of course. That debate could go on for a while yet.

Meanwhile Dubai, its planners and operators have firmly grasped the nettle of the 3 months single runway operation and made it work from day one. The cynics have been put to flight. Some say "Ah, but they've cut back too much". They ignore that hidden critical point, the right side of which the planners have stayed regardless no doubt of urgings to increase the risk. They got it right.

 Back now to the mathematicians, statisticians and physicists to produce winning formulae for the world.