The Hidden Engineering of Runways

Here's the one-minute version from the FAA.[1]

Runway overrun areas marked with diagonal stripes have an Engineered Materials Arresting System. There are several different materials used. One is pumice embedded in styrofoam, with a thin concrete layer on top. Large aircraft weigh enough to break through, and the pumice is crushed to powder, absorbing energy. This yields a surprisingly short stopping distance. The aircraft landing gear will be damaged, but the rest of the aircraft is usually intact. The overrun material comes in prebuilt blocks, and after an overrun, only the ones damaged need to be replaced.

It gets a lot of use. The FAA has logged 25 overruns stopped by EMAS, out of 161 runway ends so equipped. That's surprisingly high.

It's a simple, clever system.

[1] https://www.youtube.com/watch?v=hVSvU06_NGE

I saw a talk a long time ago about the structural aspects of runway design. The most interested fact I remember was that the stresses on the runway generated by departures was higher than those of arrivals, as departures repeatedly stress the same part of the runway, while jets land on a much more distributed area of the runway.

Plus jets weigh a lot less at arrival than at departure.

I absolutely love that Grady includes full transcripts of his videos.

It's much faster to read the article than watch the video, even though that hurts him by 1 view.

I just watched parts of the video after reading because I wanted to see his explanations.

One of the few really good creators out there.

I absolutely love this channel. It provides a reasonably no nonsense view into parts of engineering I'm not super familiar with. It's made cooler by the fact that I occasionally interact with the systems being described. (Though hopefully not this one).

Does anyone have recommendations for similar high quality engineering adjacent content?

Video is great, came up in my youtube recommendation cycle last week.

Honestly one of the better things youtube has pitched to me, the quality/relevance of the rest of its recommendations have been nose diving over the last year (or so it feels).

We had group coding projects at university, and the first one was always "sponsored" by the local airport. I think the ATC manager was friends with a lecturer. Every year the students built to the same spec in groups, being able to compare and contrast. It was great fun.

The year before me was all about runway markings: take a bunch of industry specified XML describing the runway and produce accurate diagrams in a GUI browser.

My year was runway "redeclaration", if a vehicle has broken down on the runway, you can still use the runway as a shorter strip, accounting for the onion layers of different zones radiating out from the tarmac itself, accounting for the height of the obstacle and angles of approach, accounting for all the necessary safety margins.

It was my first real exposure to working in a team and to solving a real world problem with a good spec. Of course it was an absolute shitshow, but I look back on it fondly.

I can never watch just a minute of these guy’s video — it’s always the whole thing, always so interesting.

Something which still confuses me is the nature of the illuminations in the roadway. Because we can see edge elements, we see things on stalks. I don't see how that can work, for things the tires run over. But, the illuminations are there. They must be super-designed cats-eyes.

Also, the approach lighting has very good engineering to keep you in the safe slot for approach angle. The lights must have fresnel lenses or shading or something to keep a very narrow angle of approach lit up "best"

On take off if I have a window, I now look for the banding which I mentally model as "not yet.. " "almost .." "if you are doing <x> kph then YES" .. and "nope. don't wanna see this one"

Gate approach, there are clues that pilots drive by following lines. So many lines! marked by aircraft type: if you are a <this> then follow <this track> type markers.

He does such great videos and content. Might have to watch this one with my dad; he used to joke that his Eagle Scout project was putting in the north-south runway at MCI.