- AREMA C&S Manual: Recommended Vital Circuit Design Guidelines for Highway Traffic Signal Interconnection
- Illinois Commerce Commission: Specifications and Design Criteria for Traffic Signal Control Equipment at Locations Interconnected with Railroad Warning Devices, Chicago
- Minnesota DOT: Double Break Railroad Preempt Interconnect Circuit with Supervisor, Gate Down, and Supervisor Latch
- Minnesota DOT: Railroad Double Break Interconnect Circuit with Supervisor and Gate Down Logic
