Advance Warning     Whenever an emergency vehicle is traveling under conditions of urgency, the problem of passing through busy street intersections represents a dangerous problem to both the emergency vehicle and to the general traffic at or in the vicinity of the intersection. As discussed above, the problem has become especially severe in recent years when many drivers travel in air conditioned cars with their windows rolled up and often with the radio turned on so that they may be unable to hear the siren of an approaching emergency vehicle. Many serious accidents happen each year as a result of collisions between emergency vehicles and other traffic. In heavy city traffic there is still another problem in relation to the travel of emergency vehicles. As an emergency vehicle approaches a busy intersection and some of the drivers respond to the siren and pull to the curb and halt, as required, busy intersections become filled with vehicles standing still and often completely block the progress of the emergency vehicle. Necessity      Accordingly, there is a need for a system that will efficiently warn an operator of a motor vehicle that an approaching  emergency vehicle commands the right of way, such as police car, fire apparatus or ambulance, and will also alert the operator that he is approaching a vehicle that should be given the right of way (or that the driver may be required to stop), such as a school bus that is loading or unloading passengers. Safety       A constant concern exists for the safety of vehicles where highways intersect with railroad crossings. Despite the significant advances in technology utilized by highway vehicles and trains, collisions between trains and other vehicles continue to occur, and these accidents are generally catastrophic in nature.  Accordingly, there is a need for a system that will warn an operator of a motor vehicle of an approaching railroad train.