Mohammad,

The origin of traffic rules consists of those practices which are the 
result of human action but not the result of some specific human 
intention. These rules of conduct are social regularities. It apears 
like well-structured social patterns  which seems to be a product of 
some omniscient designing mind. In reality these rules are 
spontaneous institutions which reflects the preferences of local 
actors (in UK they prefer to rule on the left).

Rustam Romaniuc