On Santa Fe's old 4th District TCS to San Diego, the advance approach (flashing yellow) was done through another set of line wires.

On a straight battery circuit grade crossing (approach-island-approach), Santa Fe had a timer on the stick circuit to drop it out after 10 minutes. Southern Pacific apparently did not use a timer, so you could tie up a train on the far side of a crossing while still in the approach circuit. But this also allowed the stick to stay up if the track circuit failed as the train was leaving, and the next train from the opposite direction would hit a locked out circuit and not drop the XR to trigger the crossing until it hit the island - which I witnessed once. (A potential disaster but fortunately no cars or log/gravel trucks at the crossing.)

The Santa FE's 4th had Slamtraks at 90 mph as well as freights. I remember one crossing had the typically battery track circuit, but the approaches would time out for a slow train and a motion detector overlay would assume control. I've also seen SP use a GCP on top of a battery circuit, so if the GCP failed the battery circuit would keep the XR picked up. The SD&AE had some interesting circuit before the trolley. One had three approach circuits on each side of the island. The first was a timing circuit. If the train made it through before it timed out the XR would drop on the middle approach. A slower train would allow a stick circuit to pick up locking out the middle approach circuit, the approach circuit nearest the island would always drop for an approaching movement.

Most of the light rail system's technology and operating practices differ entirely from typical heavy rail practice. My previous mention of the San Diego Trolley and Sprinter was because freights do use part of the same system.