(15-11-2010, 10:06 PM)sgm1983 Wrote: I have added some additional info that I believe to be correct. If anyone disagrees or has anything extra to add please reply
Thanks
EPR / STR
1. "No reminder device on track section"; I think you mean "no reminder device applied on the reset function for the track section"- don't confuse this with EPR / SPR reminders. On a VDU this reminder is displayed as yellow bands either side of the track name, generally adjacent to the reset icon green roundel or applied to that roundel itself. Believe this may have been a signaller's responsibility for schemes such as Rugby-Nuneaton
Note the wording of NR/L2/SIG/30081,6.5.7: The controls for removal of EPR from axle counter section shall test for any reminder on the reset roundel.....
2. Since EPR is to permit restoration without aspect restriction at the end of a possession, then obviously the protecting signals should be ARAFOAL when it is applied. So although it does not insist on proving reminder collars applied to the relevant signals, it does require them to be route normal.
In the case of auto signals I think this requires the replacement facility effective.
3. Conversely wouldn't want to restore a track section at the end of the possession if it hadn't been clear before the start; hence the requirement that the track is showing clear before the EPR can be applied.
4. The EPR and STR are mutually contradictory (EPR for possessions and prevents main aspect clearance, STR for abnormal train in normal working and permits one clearance of main aspect) and therefore are locked against each other.
5. Not sure what the distinction re item 2.
Main aspect clearance
a) Need to make sure that the EPR are all removed before the resumption of normal service; hence proved in the aspect.
b) Any ARFR segment imposes aspect restriction, so for clearance of main aspect then all must be unset.
An indication is provided adjacent to the representation of each signal (on a VDU adjacent to the reminder collar) to give the signaller confidence that they may authorise the driver past the signal at danger whilst gaining the security of the interlocking. Hence this indication is given whenever the signal would be showing proceed if it were not for the application of AFRF. Hence I'd say when "a remider device is applied to the entrance and all aspect conditions are met except any ARFR set"; I think this is what you meant but my reading of your wording doesn't actually equate.
Note that this indication permits the signaller to regard the signal as operational rather than defective which is significant in regard to the rules that apply when authorisng a driver to pass signal at danger.
I think whether or not the interlocking is designed to prove that signal reminders are applied to entrance / exit signals is one of those items which have varied between schemes. Note the wording of NR/L2/SIG/30081,6.4.6: It shall not be necessary to design interlocking to enforce the application of reminder devices.....; this stops short of saying "don't". Obviously for a panel it is not practicable to enforce. The following section only requires Appropriate routes shall be proved normal in the interlocking when initiating a reset.
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Some hints follow re the completion of the various axle counter Control Tables; note that projects differ in precise headings and functionality but this broadly reflects the "Rugby" implementation of c2008.
AXLE COUNTER SPECIAL CONTROLS
This CT concerns the reset-restore functionality of the various axle counter sections which are all listed as separate lines of entry.
"Reset Requires":
List all routes from controlled signals (including GPL and pre-set shunts) that read directly (i.e not foul, flank or overlap) over the section concerned
List any auto signal that reads over the section concerned.
In fringe areas also list the slot from the adjacent box that proves normal any relevant signals reading over the section
"or EPR applied":
List the EPR section number.
auto signals / slots not proved
"or STR applied":
List the EPR section number.
auto signals not proved
"Special controls":
Add any cross references; for example "sequential track section proving controls required" at interlocking boundaries for example.
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ASPECT RESTRICTION CONTROLS
This CT defines the logic applicable for the Aspect Restriction functionality (i.e. when it is / not enforced following a reset)
"ARFR segment":
List for each section the common segments, then reverse segments, then normal segments as separate rows of entry.
"Applied- to signal /route":
List the auto signal and controlled signal routes that are held to red by the particular ARFR segment [note this can be checked by cross-reference to Signal Specials sheet].
"Applied- except when points set and detected":
List point conditions when ARFR is not applied.
"Applied- except when EPR applied":
List the EPR for the section (i.e the track section name).
"Applied- except when STRapplied":
List the STR for the section (i.e the track section name).
"Removal requires- track section occupied"
List the track(s) whose occupancy removes the ARFR; generally the track section for the ARFR segment, but may also include foul TCs in some circumstances.
"Removal requires- after route operated"
List any routes that must also be set as well as track occcupancy in order to remove ARFR; only required where there are set back moves that could mean that sweep train may not traverse whole length of that track.
"Removal requires- signal off"
Similarly used where need to prove train has traversed entire length of track section, list those signals that must be off or ready to clear.
"Points set"
Similarly where necessary list point conditions necesssary for ARFR to be removed.
"or EPR applied"
List the EPR for the flank track as condition on previous column.
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EPR / STR CONTROLS
This CT defines the functionality applicable to the EPR / STR reminders (that themselves affect the imposition of Aspect Restriction).
"Track section"
The track section to which the other controls apply. List in alphabetical order as separate rows of entry.
"Application requires- Track section clear"
The track which must be clear in order to be able to apply EPR/STR (which will always be the same identity as the first column of course).
"Application requires- Routes Normal"
List all routes from controlled signals that read directly over the affected section. Also in fringe areas those slots which ensure that contolled signals / ato signals are replaced.
"Application requires- EPR /STR not applied"
List the same track section yet again (this is the cross proving that ensures that an EPR and STR cannot be simultaneously applied).
"Removal requires- track section clear"
List the same track section yet again.
"Removal requires- routes normal"
List the same routes as for the application.
"Removal requires- special controls"
List any other locking to prevent removal.
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SPECIAL SIGNAL CONTROLS
This CT is effectively an overflow from the normal route and aspect CTs- all the axle counter related controls which are additional to those that would be needed with track circuits are shown here on the appropriate line.
"Signal / Route"
List each signal number for auto signals and each route from each controlled signal in separate rows of entry.
"Aspect Restriction not applied to Axle Counter sections / segments"
List each axle counter section / segment in the line of route or foul thereof (i.e. not overlap nor flank). Note that it is necessary to aspect restrict a route if a foul section to it has been reset, since if it were actually occupied then there is a risk of the signalled train hitting the obstruction
"STR not applied or effective for one train only"
List the STR (if provided) for each axle counter section in line of route only- not foul, flank nor overlap. Note that the train being signalled will only be occupying (and hence potentially creating a miscount) on those sections in the route itself
"EPR not applied"
List the EPR for each axle counter section in line of route only- not foul, flank nor overlap. Note that EPRs will be applied for all the track sections within the limits of the possession and hence any section upset by a train movement will be able to be reset without aspect restriction afterwards
As you can see these control tables are pretty repetitive- I think because it was felt that there needed to be a CT that exactly specified to ensure that the data is easily derived from them and to provide somewhere for the tester to tick. Don't tend to do this for interlocking more generally- I think details were included because the approach was "novel" and there wasn't the accumulated body of experience in the industry as there is for other locking.
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Although it doesn't actually address the controls, the attached powerpoint that was used to introduce the concept of EPR and STR for initial application on the WCRM some years ago does give a good idea of the overall process.
PJW