Of course. The entrance to the platform was an enchanted wall.

Edmund had been leaning against the opposite wall and just staring at the entrance and the people going through it for a good hour. He was uneasy about going through this magical doorway. Especially since it was a solid object at other times.

Vaguely wondering why muggles didn't lean on that particular wall, he came to the conclusion that there must some kind of spell that told them not to.