While driving, I have noticed a large number of trucks have now mounted additional yellow side marker lights to the fronts of their vehicles. In addition to the yellow side markers that I have seen on the fronts of these vehicles there seems to be an increasing number using blue, white and green lights. I have also seen red side marker lights fitted to the fonts of some vans and lorries, which I thought was illegal? In some cases there are often as many as ten of these lights switched on while the truck is in motion, day or night. I was wondering if you could shed some light as to the significance of these lights when they are being used in this way.