​Signs

Traffic signs are on vertical poles or lampposts, so are usually visible at a distance. (You'll see them before any markings painted on the road). They're often the first clue about a static hazard. There are very few shapes and colours:

• Circles = orders (what to do / not to do)
  
• Triangles = warnings (of specific hazards)
  
• Rectangles = info (so you can make an informed choice)
  

The more RED, the more severe a restriction (often about speed). Circles in BLUE say what you must do. BROWN tell you about heritage or leisure. GREEN lead you along main roads (“primary routes”); local places are detailed in BLACK on WHITE. And YELLOW is used for temporary changes. See an example.

The book "Know Your Traffic Signs" [KYTS] shows you almost all combinations. Here's how to decode lots at once. Tech manuals are here.