We are blind to those who walk. That's why pavements are the first casualty of street widening to accommodate cars

Have you ever noticed a footpath? Does it even exist? And if it does, what is its height above the road? What should be the ideal height that enables pedestrians to walk without the fear of being run over or breaking a leg clambering onto the footpath and, at the same time, doesn't allow cars to park and take over this public space?