Too my knowledge it is burning of money (simulated) for the dead

It is more prominent in  April (i think the 4th) when they have a holiday to sweep the graves

Jeez, you must be new. Yeah, it's a way to give money to the dead. 

Tomb Sweeping day is called Qingming, it is not on April 4th as it is according to the lunar calendar (but it is about that time of year)

The burning of fake money as worship to the dead also happens on e.g. anniversaries relating to the deceased, I would think people should go to the grave for doing this, but those you see at the roadside or other places may be because that was where the dead died or because it is not practically possible to go to the tomb. Maybe some also just do it if they happen to miss their loved-one on that day.

Try to search for keywords "joss money" or "qingming"

The idea behind it, as I've been lead to understand it, is that the spirits of the dead can become benevolent if treated well but can curse the living if they are neglected. This actually tells us something rather profound about Chinese conceptualizations of the universe in a spiritual sense. Specifically, the reward for ones actions on earth is based around being loved and remember by ones descendants through eternity. Right and wrong then, can be said to be determined primarily by how they effect the family, or institutions that are judged to be family like.

Anyway, it is a charming ritual, and I would like to actually watch somebody do it in its entirety, but I can never seem to work up the nerve as I feel like I'm intruding on something that should be private.