Possible basic problem with OS: No visibility does not allow speed. For failed LX: OS vs. packet 88 indication: If the driver sees the packet 88 indicator, why do we need OS for a failed LX (doesn't he know what he needs by what packet 88 will do to train/DMI)? Can OS be used instead of packet 88 indication (OS is also used in other situations that can occure at the same time and loacation as the the failed LX => thus difficult/impossible for the driver to distinguish the possible situations)?
It is up to each railway to decide how to manage level crossings - there is no right or wrong way of doing it, and all ways have advantages or disadvantages. Packet 88 can be used in normal operation so the driver sees the unprotected icon until the crossing has worked and then it is removed once the crossing is proved. Or it can just be reserved for when the crossing is failed. But when you use it you need to consider what would happen if there was a temporary speed restriction in the area, or if other parts of the system require a degraded operation and what about if there is no MA on board and you are in SR. ETCS is easy when everything is working, trying to think through all the degraded and edge events is challenging!
If new AHB are not being installed, what justifies all this development cost for prediction for automatic crossings? The problems involved seem mostly reducible to existing solutions (with a few optimizations) if every crossing on a route is interlocked. I'd imagine the whole-life cost could easily be competitive to replace or remove AHBs when fitting ETCS.
You make a good point and it does not seem like it would be worthwhile developing a solution unless you have a route where one wants to introduce ETCS but there is no business case to replace the existing AHB type crossings, particularly if they already have issues due to stations being nearby.
Possible basic problem with OS: No visibility does not allow speed.
For failed LX: OS vs. packet 88 indication: If the driver sees the packet 88 indicator, why do we need OS for a failed LX (doesn't he know what he needs by what packet 88 will do to train/DMI)? Can OS be used instead of packet 88 indication (OS is also used in other situations that can occure at the same time and loacation as the the failed LX => thus difficult/impossible for the driver to distinguish the possible situations)?
It is up to each railway to decide how to manage level crossings - there is no right or wrong way of doing it, and all ways have advantages or disadvantages.
Packet 88 can be used in normal operation so the driver sees the unprotected icon until the crossing has worked and then it is removed once the crossing is proved. Or it can just be reserved for when the crossing is failed. But when you use it you need to consider what would happen if there was a temporary speed restriction in the area, or if other parts of the system require a degraded operation and what about if there is no MA on board and you are in SR.
ETCS is easy when everything is working, trying to think through all the degraded and edge events is challenging!
If new AHB are not being installed, what justifies all this development cost for prediction for automatic crossings? The problems involved seem mostly reducible to existing solutions (with a few optimizations) if every crossing on a route is interlocked. I'd imagine the whole-life cost could easily be competitive to replace or remove AHBs when fitting ETCS.
You make a good point and it does not seem like it would be worthwhile developing a solution unless you have a route where one wants to introduce ETCS but there is no business case to replace the existing AHB type crossings, particularly if they already have issues due to stations being nearby.