People at the railway station.
Personally, I advocate for traffic rules in stations. People see a shop or a thing, and immediately dart towards their destination with no regard for.. other humans which might exist around them.
And thus, pandemonium reigns.
It often becomes impossible to board your train on time without arriving early. Trolleys will cut you off, people will run into you (remember, they're not actually aware that you exist until the moment of collision), form walls with their entourage which plows through the masses like a swath of destruction (this is also the case in shopping streets, malls et c.), among many other horrible aspects. My old physics teacher once said that masses of humans tend to behave like water molecules. That is to say, find the shortest path and arrive as fast as the medium allows. I however think that this is not taking into account the random interactions, bumping-into's and swirling around's of a good 99.999...9% of those molecules. Big things just always.. move slowly.
That is why I propound regular traffic rules for stations, and in addition, no idling. Just like the weakest link determines the strength of a chain, the slowest person on their way down the stairs determines the speed of the human grapevine behind them. And that blows.
To further understand this point, imagine road works on the motorway. It's 3 kilometers long.
You draw level with a lorry which is driving on the right lane at 60 km/h and you proceed to drive on the left lane at 58 km/h.
Right at the very end of the construction, check your mirror for the face of the person in the car behind you.
That's... humans.