Pre-collision systems are active safety systems for automobiles to avoid or minimize the extent of damage in the event of a collision. These systems evaluate the position of the driver and his environment constantly to predict a likely accident and take steps in advance to minimize injury. They may either beef up the active safety systems in the car or even brake automatically to bring the car to a halt. In the event of accident occurring due to some reasons the system is equipped with the safety measures such as GPS and GSM to send an alarm message to the person concerned regarding the location and time of the accident. The pre-collision system is radar based, using ultrasonic waves so as to monitor the car's environment constantly. This system can detect the position, distance and relative velocity of the vehicle in front of the car at any time. The safety system is a satellite based communication medium using GPS and GSM to alert the person concerned in the event of accident.