The bottom color of the warning sign is yellow.
The bottom color of the ban sign is red,
The background color of the indication and finger marks is blue.
After many experiments psychologist concluded that for smaller targets, red legibility, attractiveness and recognition of the best, but for larger targets, yellow legibility, attractiveness and recognition of the best, therefore, the traffic management will be red and yellow respectively for the prohibition and the warning signs (signal). In addition, due to the readability of the blue is best, therefore, instructions and sign traffic signs in the blue and white, so the driver can read the indication of where the meaning of quickly, to ensure traffic safety.