Complex sentence: Under Conrail the CR&I was designated as an industrial track, its lowest classification, and with the PRR era crossing agreement with the Alton successor Illinois Central Railroad still in effect, Conrail had little incentive to upgrade the signaling on the line.
Split into simpler sentences: Under Conrail the CR&I was designated as an industrial track, its lowest classification. Since the PRR era crossing agreement with the Alton successor Illinois Central Railroad was still in effect, Conrail had little incentive to upgrade the signaling on the line.