and the two traffic cones in the picture are just priceless.
The Police rule book obviously says that a sign must be placed at the scene of any accident, together with traffic cones, so that's what they did - just in case another car came along and skidded into the first one.
While I agree the sign and the cones appear to be pointless you should consider the possibility that someone may came along later and "find" a car which has crashed through the ice and assume that it has just happened and then try to rescue the driver. This would put the potential hero in considerable danger and could lead to loss of life.
The cones and sign would indicate that the authorities already know about the situation and avert a dangerous "rescue".