TORR- Train Operated Route Release

[PJW]

To ask a question; would that not be considered as similar to the signallar pulling the button. The real checking for validity to pull the route is still completed within the locking, hence SIL4? I guess it is an interesting question whether TORR needs to be SIL4 whereas we all accept the route setting/release must be. After all, a signaller certainly isn't SIL4!

Comments?

Indeed, I think that is the argument. This effectively did come up as an IRSE question in the last couple of years.