There are over 223,000 railroad grade crossings in the United States alone. Most of these crossings, especially those in rural areas, have only warning signs to alert motorists to the danger posed by an approaching train. Typical of railroad grade crossing warning signs is the familiar X-shaped "RAILROAD CROSSING" sign or "crossbuck." Warning signs, however, only alert motorists to the presence of a railroad crossing and do not alert them to the presence of an oncoming train. Often, a motorist may fail to see an approaching train because he was distracted or because his view of the train was obstructed by environmental conditions or darkness. Consequently, collisions between trains and automobiles at railroad crossings account for thousands of accidents each year, many of which result in extensive property damage and serious injury or death to motorists.
Known to the art are active railroad crossing warning systems utilizing the railroad tracks themselves to detect an approaching train and activate warning signal apparatus such as flashing lights and bells. These systems warn motorists when a train is detected at a predetermined distance from the crossing. However, present active warning systems do no take into account the speed of the train and thus make no allowance for the time it will take the train to reach the crossing. For example, a fast moving train may reach the crossing in only a few seconds after it is detected, while a slow moving train may fail to reach the crossing until several minutes have passed. Motorists may become impatient waiting for slow moving trains to reach the crossing. Consequently, some motorists may begin to ignore the warnings and attempt to cross the tracks possibly causing an accident should a fast moving train be encountered. Further, installation of current active warning systems may require the insulation and resetting of great lengths of track. Additionally, these systems may require the installation of expensive high voltage transformers, relays, and batteries for backup systems. Unfortunately, many rural crossings are not conducive to the installation of active warning systems that requires AC electrical power and extensive grade preparation. Consequently, these crossings usually remain inadequately protected. High speed rail corridors being proposed across the United States will only exacerbate this problem. These corridors will require improved crossing warning systems to properly secure the safety of both passengers and motorists.