Preempt Priorities

There are many forms of preemption that may occur at a
TSC, including:
  • Emergency vehicles.
  • Public transportation vehicles.
The TMUTCD states that railroad preemption is the highest priority within the
TSC
 when multiple preempts exists. The designer should
also
 confirm:
  • TSC
     has enough preempt plans to support all preempt modes.
  • Traffic signal cabinet has enough relays to support all preempts.
  • Solid state preemption controllers may be used to eliminate the need for preempt relays.
When using multiple preemption circuits for railroad preemption, the circuits must be prioritized in the
TSC
 to ensure the preemption functions as designed.