We have a bit of a discussion with the administration of our university about putting up posters on the glass doors in our campus buildings.

The hallways have a lot of doors made of glass which would make a great place for people to see information while they walk through. There is a rule here that forbids bill-sticking on these doors with the single reason that if the glass door is not 100% transparent anymore, people will hurt themselves on a regular basis because they cannot see if other people are on the opposite side of it.

For some reason this does not seems to happen though with every other type of door that is not transparent.

Is this just bureaucratic nonsense or are there any studies/experiments that actually proof that more accidents occur with glass doors that have an obscured view?