The friend I spent Christmas Day with lives a 30-mile drive away, and to get there part of my journey is along the M25 London Orbital motorway. This bridge runs across it at a place called
Polhill. For generations Polhill was a place of beauty, where families would go in spring to pick bluebells. Then the developers decided in their wisdom to reduce it to a cutting on the motorway.
The story is that, when planning the motorway and its crossings, exits and entries, thsoe responsible looked at a map, and at this site saw a line. "Aha!" they said, "There's a road. We must build a bridge across the motorway to accommodate it." And so they built this award-winning scissor arch bridge.
Sadly, the line on the map was just...a line on a map! A multi-million pound line. No one checked it on the ground. If you google bridges on the M25, you find that the Kent Sub Unit of South East Road Construction Unit takes responsibility for the design of what is described as a "pedestrian bridge, the Polhill Bridleway". I have never Seen anything on the bridge, nor have I tried to find the way on to it, but if there is a way, it's certainly well hidden. Well, at that price, I suppose they can afford to hide their mistake.