Adaptive cruise control system that is used in modern vehicles are highly helpful and very similar to already existing cruise control system model.But the difference between both is that ACC has the capabilities to supervise the environment and take decisions based on the constraints.A vehicle equipped with adaptive cruise control system can monitor the exterior of the ego vehicle through an optical sensor and accelerate or decelerate accordingly.In case of absence of a preceding vehicle or an obstacle, the system guides the vehicle to move at a constant set velocity.When the preceding vehicle or the obstacle is inside the proximity range, then the system switches from speed control to spacing control.In spacing control, the acceleration and braking systems both are overridden from manual mode and when the proximity range has reached the threshold, the algorithm calculates the appropriate speed for the scenario and applies brakes in case it is necessary