Here is a local authority advertising sign on the footway in Northampton. My local authority has decided to help balance the books by placing advertising signs around the town centre. The detail on the right shows the lethal section adopted for the sign support, a skull-splitting knife edge. Do not think that these signs will not be hit by vehicles in a 30mph limit. The tarmac reinstatement around the base is evidence of a recent demolition by an errant vehicle. And what is the cost of a fatality? It is measured in millions. No doubt enough to outweigh any income accrued from the hoarding

Overkill?

The new matrix signs on the M1.  These seem to be a bit of a dog's dinner?  The designer, having decided that the worst thing that can happen is that a vehicle runs into the sign, has made every effort to avoid that 'catastrophe'. The sign is mounted on a block of concrete standing proud of the verge.  This would be lethal to any vehicle hitting it so it is protected by a three bar safety fence. The sign itself is built in battleship proportions.  Would it have been possible at the very start of the design process to make the sign less liable to being hit by using a gantry mounting which could have been further back on the verge,  and make the supports lighter and frangible, so that vehicle impact, although destroying the sign would not have damaged the vehicle or its contents?  I will post some photos of such signs erected in UK with just such an approach.