The brilliance of the British Rail Double Arrow isn’t just in its clever symbolism. Many people who have tired to reproduce over the years have mistakenly believed that its a case of organising five lines in a basic geometric order.
Gerry Barney who designed it when working for Design Research Unit (DRU), introduced many tiny optical corrections. However, the real genius is how these refinements were systemised. Its one thing to create visually accurate marque but its quite another to design it in such away that it allowed other designers, sign painters or engineers to reproduce it perfectly. The symbol can be drawn from an eight by five base unit gird, with subdivisions of six which in further divisions of four.