Perhaps the best way to design a railway crossing system that is intelligent is to start by considering mathematical models for such systems. One of the great advantages in the mathematics of railway systems is that one can identity properties that must be satisfied by such systems that effective as well as safe. An example of this approach is given in
S.A. Khan, Formal Analysis of Safety Properties of Railway Interlocking Systems, Ph.D. Thesis, University of Central Punjab, 2011:
http://prr.hec.gov.pk/Thesis/1060S.pdf
See, for example, Khan's introduction to Petri nets, starting on page 34.
See, also, Khan's introduction to graph-theoretic models of railway crossings, starting on page 49.
You should start with safety requirements - neural networks allow some fuzzyness of a result, the question is do safety measures allow this fuzzyness. In Poland safety reuqirements are set so high, that the problem becomes simplified.