Railroad signaling and communication system using a fail-safe voltage sensor to verify trackside conditions in safety-critical railroad applications

Abstract

A method and system for verifying trackside conditions in safety critical railroad applications by reporting the status of trackside signals and switches to a remote train control system. The system comprises at least one sensor for providing trackside conditions electrically connected to a circuit for providing trackside conditions to a railroad, said sensor being powered by voltage applied to the circuit such that the sensor is energized only when said electrical component is engaged. The system and method further comprises a method and system which is failsafe and which enables the control system to independently verify signals from each sensor.

We claim: 
     
         1 . A system for verifying whether an electrical component is energized comprising:
 a sensor electrically connected to a circuit adjacent to an electrical component, said sensor powered by voltage applied to said circuit such that said sensor is energized only when said electrical component is engaged.   
     
     
         2 . The system of  claim 1  wherein:
 said sensor has a low power microprocessor. 
 
     
     
         3 . The system of  claim 2  wherein:
 said sensor has a means of two way electronic communication. 
 
     
     
         4 . A fail safe method for sensing the status of an electrical component by powering the sensing means with voltage applied to a circuit when the electrical component is engaged comprising:
 electrically connecting a sensor to an electrical circuit associated with an electrical component, said circuit energized when said electrical component is engaged, said sensor adjacent to said electrical component;   powering said sensor by voltage applied to said circuit such that said sensor is energized only when said circuit is energized; and   indicating that said electrical component is engaged when sensor is energized by transmitting sensor status to a remote train control system.   
     
     
         5 . The method of  claim 4  wherein:
 said electrical component is a relay; said circuit is energized when said relay is closed and said sensor is positioned after said relay such that said sensor is energized when said relay is closed. 
 
     
     
         6 . The method of  claim 4  wherein:
 said electrical component is a switch contact; said circuit is energized when said switch contact is closed and said sensor is positioned after said switch contact such that said sensor is energized when said switch contact is closed.