Samenvatting
A suggestion to surround the through lights for bus and tram with white rings, by way of pre-information, was tested for so-called phantom-effects. There was some fear that these rings would, at large distances, merge with the enclosed lights and make these appear to be alight. This fear could be taken away. Some other improvements like a canopy, the clarity of the ring configuration and the convexity of the cover glasses are mentioned.