If dead reckoning is what you're relying on, you need * the last junction you passed and how you exited, and * number of turns of the wheel. The issue is tha

If dead reckoning is what you're relying on, you need * the last junction you passed and how you exited, and * number of turns of the wheel. The issue is that rewiring junctions is very expensive, upgrading trains to be compatible is expensive, etc. Even more so if you cannot upgrade an entire network all at once, and you need to account for mixed operations with both new and legacy compatible systems.