Hi,

So a recent flight arrived into Gate 21 of T3, and I was interested that this is one of the (only?) remaining piers in LHR without full segregation of arriving and departing passengers. Instead, passengers are segregated by glass screens, and opening and closing doors through those screens where the paths of arriving and departing passengers cross over.

For gates 16 through 21, it's obvious how this works as those gates are on the correct ("northern") side of the segregated passageway that leads back to immigration, so all they have to do is turn left down the segregated corridor.

But I spent a bit of time looking at gates 15 through 13, and wondered how arrivals into those gates reach the arrivals corridor! I don't think I've ever used those gates (I don't think BA flights often go from them!). I noticed there is a door leading through the arrivals corridor and into the departure lounge toward gates 15-13, but that's marked "electric vehicles only" so I can't believe that is the route. It doesn't look like there is another floor - although appearances may be deceptive..!

Thanks in advance for anyone who can satisfy my curiosity!

Here's a quick diagram (from memory) of what I'm referring to: