(This speed is used by the Department for Transport in the UK to set the timing on pedestrian crossings. The problem is that according to a report published in the journal Aga and Ageing, 76% of men and 85% of women over the age of 65 have a walking speed slower than that. This means they struggle to cross the road before the green man turns red (pedestrian crossings in the UK use little green men (see the picture - they're not aliens). I have to add that 100% of people with a bad back struggle too!)