This exact situation literally happened the last time I was at Penn Station trying to get on an NJ transit train. It was a madhouse to get to the track when they announced it as it was the first train heading to EWR in like an hour, so a huge crowd starts going down the escalator to the track. While i’m on the escalator they make an announcement that the train is actually departing from a different track, and because people are idiots everyone just stopped where the escalator ended. It was completely packed and me and everyone else on the escalator realized that no one at the bottom was moving and people reaching the bottom were being shoved into the crowd with no place to go so people started shouting at the crowd to move (including me). People did have room to move unlike in this case but it was still pretty scary being at the top of an escalator and looking down and realizing you’re moving towards a huge mass of people with nowhere to go and no way to stop moving. When I did get to the bottom lots of people were shoving each other and tripping, luckily I don’t think anyone got trampled and the crowd finally started to disperse but it was crazy to be reminded how stupid people can be. It definitely didn’t help that I’m sure lots of the people there were tourists going to the airport with huge luggage who had never taken a train from Penn Station before.