Currently, in the whole world, enormous electric energy is consumed by the street lights, which are automatically turn on when it becomes dark and automatically turn off when it becomes bright. This is the huge waste of energy in the whole world and should be changed. This project is a smart street light system where I am introducing a street light/lamp that efficiently(saves energy) manages electricity usage by turning on automatically before dusk and turn off at dawn and it uses dim lightning when no motion is detected.It will increase light intensity only when motion is detected(ie when pedestrians walk or vehicle is on the road). The main aim of this is that lights turn on when needed and dim light when not needed. The smart street light system consists of LED lights, brightness sensors, motion sensors and short-distance communication networks. The lights turn on before pedestrians and vehicles come and reduce brightness when there is no one.This project is about Smart street light, street light will turn on while vehicle is passing through it.Here we are using IR Sensors that senses the position of the vehicle,each IR sensor controls LED’s. When vehicle passes by a particular IR sensor it senses the position of vehicle and gives its signal to the arduino board and it will turn on the LED’s.Firstly, LDR will sense the intensity value of sunlight and send it to Arduino. Arduino will judge if the received value is above the threshold level (which is set independently by the user from the discrete value: 0-2023), then it will consider it as day-time and LEDs will remain OFF, or if the received value below the threshold level, Arduino will consider it as a night-time. In the night-time, if the value of IR obstacle detector sensor is LOW and detects no object, then DIM LEDs (half of its maximum voltage) will glow, or if IR obstacle detector value is HIGH and detects any object, then HIGH LEDs (full of its maximum voltage)will glow. Arduino will also count the total number of vehicles that crossed the street in the night-time with the help of IR obstacle detection sensor and will demonstrate it to the serial monitor.If we uses this idea and implement to it in our society it will be helpful in saving enough amount of electricity and money.