Re: I think that Clem is talking about traffic signal timing integration, not the rail signals...
He might also be thinking about how Amtrak's
ITCS was supposed to include advance grade crossing activation for the higher speed trains, not using track circuits, iirc including sensing of grade crossing activation though that's not mentioned in the FRA blurb. It was an early version of PTC to support 110 mph operation on part of the line to Detroit.