Most of the times people near the traffic signals wasting time because of the particular time is fixed in changing signal eventhough no one is moving. Hence by using the sensors (like SICK's mid range distance sensors-DL50 which are cheaper and accurate), shifting of the signal will change automatically by detecting the vehicle presence or humans from the sensors which are fixed above the traffic signal. These sensors have measuring range from 200mm to 50000mm. Response time of 15ms/30ms and a good repeatability of 3mm/2mm.

Also another kind of sensors(like AMR-Anisotropic Magnetoresistive sensors) placed below the ground surface which measures the vehicle or human presence by using the magnetic field. Whenever nothing is passing over this sensor, will send the output to shift to next signal with in a very short time. This way we can control traffic signals more accurately.

Note: When vehicles are continuously passing, then shifting of signal will take place at maximum set up time period which we will put up in code.

Conclusion:
This idea helps when no one is passing in the road where the traffic signal green is indicated with in a maximum time period. Also this helps in most of the towns but not in cities because in cities traffic is always continuous. In cities the current running traffic signals are more accurate than my proposal.

A draft image is attached to just visualize the working principle.