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Re: Robust Communications Options for PTC-Less dependence on track circuits.
Author: BOB2
Date: 09-25-2009 - 08:21
OPB,
This is why the communications integration and standards are critical for PTC. I am very much in favor of looking at more use of robust wireless DSRC for communications with wayside devices, like signals, reducing sole dependency on track circuits.
We've been developing a number of DSRC standards for highway information interfaces for years, that we haven't really used that much, yet. For a "closed" system like a railroad, this should be somewhat easier, and a priority. I'm just a dumb economist, who's worked with these real ITS engineers on the needs side, so others may want to comment on the technical aspect of DSRC. But, it is my understanding, this DSRC technology came out of military applications and is pretty reliable, has a high rate of data transmission, and is not prone to much interference in these short ranges. That would add another layer of communications reliability and redundancy to assure that failure of one mode information flow will still be supplemented by other communication inputs.
This strategy might make integration and retrofit of wayside devices rather cheap, as well. While some people still tear up streets to put in magnetic resonance loops for bus priority systems at intersections, to detect the large metal objects like buses, the really smart people are simply using very reliable two way transponders on the vehicles, and putting an add on two way DSRC com circuit in the signal controller box.
This type of approach would add another layer, beside the satellite, and the track circuit, to a PTC system, but if the communications system architecture is robust, this should not be a problem.
PTC should be part of an integrated multilayerd and highly robust safety and control system, with additional levels of protection and oversight. So I agree with your views on the default design conditions. There is a danger that I see, especially as a "dumb economist", who once ran a train, that some may want to opt for a PTC "lite" solution, as a seperate stand alone system, not a fully layered and integrated system, and without the level of com redundancy and fault protection you favor, because they want to do it on the cheap.
This is why the communications integration and standards are critical for PTC. I am very much in favor of looking at more use of robust wireless DSRC for communications with wayside devices, like signals, reducing sole dependency on track circuits.
We've been developing a number of DSRC standards for highway information interfaces for years, that we haven't really used that much, yet. For a "closed" system like a railroad, this should be somewhat easier, and a priority. I'm just a dumb economist, who's worked with these real ITS engineers on the needs side, so others may want to comment on the technical aspect of DSRC. But, it is my understanding, this DSRC technology came out of military applications and is pretty reliable, has a high rate of data transmission, and is not prone to much interference in these short ranges. That would add another layer of communications reliability and redundancy to assure that failure of one mode information flow will still be supplemented by other communication inputs.
This strategy might make integration and retrofit of wayside devices rather cheap, as well. While some people still tear up streets to put in magnetic resonance loops for bus priority systems at intersections, to detect the large metal objects like buses, the really smart people are simply using very reliable two way transponders on the vehicles, and putting an add on two way DSRC com circuit in the signal controller box.
This type of approach would add another layer, beside the satellite, and the track circuit, to a PTC system, but if the communications system architecture is robust, this should not be a problem.
PTC should be part of an integrated multilayerd and highly robust safety and control system, with additional levels of protection and oversight. So I agree with your views on the default design conditions. There is a danger that I see, especially as a "dumb economist", who once ran a train, that some may want to opt for a PTC "lite" solution, as a seperate stand alone system, not a fully layered and integrated system, and without the level of com redundancy and fault protection you favor, because they want to do it on the cheap.
