Countdown to last commuter train

Tonight's train ride home was a bad one.
Usually on a Friday evening I have to take a fairly packed commuter train home. But today was worse than usual.
This morning there was some fault on the track, so the trains were all delayed by about three minutes. No big deal, you might think. But three minutes has a huge impact on a system that carries millions of passengers every evening.
The carriage was so crowded that, even though I had a terrible itchy nose, I couldn't raise my arm to scratch it. Can you imagine how awful that feels?
The other passeners were lucky I'm tall: I was a good head and shoulder's above everyone else. If I had been smaller, I would have found the nearest person's shoulder and rubbed my nose up and down on their shirt until the desire to itch had been sated.