As it turns out, block occupancy detection is possible and economical (in terms of equipment cost) with an Arduino and some sensors. In this post I’ll talk about and demonstrate what I’ve learned so far about the electronics of block occupancy detection.
Block Detection Option: Block detection can be turned on with an Accessory Command for testing signals even with nothing in the block. This feature can also be used to turn the signals red to protect a crossing.
The DCCBD is a Digital Command Control (DCC) track occupancy detector for model railroads. This detector uses the current-detection method of determining train presence.