Wednesday, March 11, 2009

Maximizing airport runway & boarding gates utilization at London Heathrow

Have you transferred at or departed from the London Heathrow airport lately? Did you notice how the boarding gates remain unassigned until approximately 40 minutes before departure for the inter-European flights?  See picture below. I noticed them doing this at least 2 years ago, but now as an Operational Research professional, I can appreciate some of the intuition behind it.
It allows the runway and boarding gate planners a lot of flexibility so that if a flight is late, the planner can easily swap gates and runways if needed with minimum communication to the parties involved. In terms of communication, it is less hassle and less mistake-prone. In terms of an optimization problem, this flexibility means fewer constraints, and therefore better solutions potentially.

Interesting note: see how there are 4 flights scheduled at 19:05 for departure? My flight was the 19:05 to Prague, and I was able to see that there were basically 2 runways for the group of gates in my area, and several planes (about 4) were lined up like ducks in a row waiting for their turns to take off one by one. However, the individual take off is quite fast. Therefore, even though the 19:05 departure time is somewhat approximate for the 4 flights, my flight to Prague certainly arrived on time nonetheless.

As a passenger, it was slightly annoying that when I arrived at Heathrow, I did not know which gate to sit at to wait for my departing flight. However, I was quickly assured that this would not be a problem, because another information board tells me how long it would take to get from where I am to another gate, so I did not need to worry about being late for boarding. See picture below.

I suppose this could also be applied to the domestic flights in other parts of the world, such as the USA and Canada.


Anonymous said...
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Houelb said...

I know it's a old post but I just discover this blog right now and I already love it.
Congratulations. Too few people have energy to blog about OR.

Just to tell that at least in France we have a similar assignment system for planes but also for trains in railway stations. The couple train and platform are shown only 20 minutes before starting I guess for the reasons you told.

I like your example especially because I think it's a quit good way to explain the use of OR in real life for my friends who don't understand what about is my PhD.

Dawen said...

Ah, yes, the identity crisis of operational research. Thanks for your comment and your kind words about the blog. Very encouraging.

As for railway platform assignment, it is the same in London's major train stations as well, i.e. Kings Cross and Victoria. It often creates chaos as heaps of people just sit or stand in front of the massive signs blocking traffic in the middle of the station. Then you see the swarm movement once the platforms are assigned and people all rush towards one direction. I wonder how often those platforms actually change, and if there are other operational reasons behind the late assignment (i.e. allow the passengers room and time to get off the train first before new passengers try to get on?). Often the trains I take going to various destinations depart from the same platforms, although my sample size is rather small.

If you ever find the energy to blog about OR, drop me a line at dawen [at] thinkor [dot] org, and I can add you as one of our contributors to the blog. :)


Unknown said...

I am intensely curious to learn just how dynamic the platform assignment is. I know that every day I get on at platform 9 to work and 5 coming home and as far as I know those platform allocations are established months in advance. But, what about King's Cross or Euston? My train last Saturday to Liverpool was not announced until 15-20 minutes before departure. Was this because they didn't know what platform it would be at until then, or because they didn't want me to know until then?

This is the central question remaining: Is the delayed release of platform/gate information done so because gates are allocated late in an operation optimization activity, or are gates announced late as a human management action?

Unfortunately it seems to be the long distance trains where this happens the most. In this case it is least unlikely that someone takes it on a daily basis and can satisfy my curiosity. Additionally the long distance trains have the most customers with assigned seats and significant baggage, so there is more motivation to decrease congestion by withholding platform information until the train has emptied.

Houelb said...

@Aleksey I really hope the railway directors don't do that only to make the passengers crazy ;-)
I think it's because farther the origin city is bigger the incidents and delays probability is. My point of view is they just want to keep flexibility in case of problems appear.

Imagine if all the passengers for long distance train know in advances the platform number and 10 minutes before starting they have to move to another platform because a delay creates a new assignment. It means they have to move with as you say "the most customers with assigned seats and significant baggage" I guess maybe it's better they just wait in the railway hall and go to the platform only when the allocation is sure.

@Dawen I'm pretty honored by your proposition and be sure that if I find the energy (and time) to write something about OR I will send you it. Thanks

PS: sorry for my rusty english, I don't use it daily and sometimes it's a little bit paintful ;-)