 To prove to have paid this fee, the toll stickers have to be put onto the inside of the front windscreen.Once removed, they no longer are valid, so each car on Austrian Autobahns needs its own toll sticker.Since 2004 trucks must carry the "GO-Box", a little white box which counts the length of the Autobahn used by way of electrical control points, queried by overhead DSRC microwave radio transceivers at different locations.