The subject of railroad pre-emption has historically not received much attention in professional literature. All aspects of pre-emption need to be studied and reported on in greater detail. This research examined and compared the pre-emption capabilities of a number of currently marketed actuated traffic signal controllers based on the national electrical manufacturers association standard. Shortcomings in their pre-emption logic were identified, and pre-emption issues were discussed in terms of their operations. The evaluation was conducted from a pragmatic point of view to determine whether modern controllers allow practical and reasonable pre-emption design in conformance with accepted traffic engineering practice. Recommendations are offered with respect to minimum desirable operational capabilities, as well as railroad pre-emption nomenclature and user documentation.
Abstract