i want to know how to make traffic light using sensors
That's not going to buy him anything in India. From State Dept travel advisory: On Indian roads, the safest driving policy is to always assume that other drivers will not respond to a traffic situation in the same way you would inthe United States. On Indian roads, might makes right, and buses and trucks epitomize this fact. Buses and trucks often run red lights and merge directly into traffic at yield points and traffic circles. Cars, auto-rickshaws, bicycles, and pedestrians behave only slightly more cautiously. Use your horn or flash your headlights frequently to announce your presence. It is both customary and wise. ...and God help you if you hit one of those sacred cows. http://travel.state.gov/travel/cis_pa_tw/cis/cis_1139.html#traffic_safety
Grin... It pretty hard to make light from most sensors. You'll have a much easier time making a traffic light using 'lights'. :^) George H.