Our contributor TG manages to get up and over l'alpe des neuf abres, and in six minutes is viewing trouble on Horfield Road. Someone has put a warning sign up. Clearly it is discouraging traffic. It is also making the cusp of the hill extra tricky for the little car that has just managed to get all way up the steepest stretch.
Just to the left of that photo is this scene, where somone has managed to skid into the railings. While normally those railings appear to be an inconvenient bit of anti-car council planning, there to stop you parking on the pavement, today they keep the pavement and the car separate with reason.
That car going past this crash, carrying on down the hill has its brake lights on, as they say in the French Alps "les feux touristique" - tourist lights. You should be using engine braking down here, not the brakes, though with ABS they are somewhat better at stopping than they used to be.