A railroad monitoring apparatus includes first and second diverse vital processing units, first and second current sensors configured to measure the current being provided to one or more signaling elements of an item of wayside signaling equipment, and means for measuring voltage levels being supplied to each of the signaling elements. The first processing unit receives a first current measurement from the first current sensor and the measured voltage levels, and the second vital processing unit receives a second current measurement from the second current sensor and the measured voltage levels. The vital processing units are each programmed to determine based on one or more of the first current measurement, the second current measurement and the measured voltage levels: (i) the state of the item of railroad wayside signaling equipment, (ii) failures within the item of railroad wayside signaling equipment, and (iii) failures within the monitoring apparatus itself.