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| Uddingston Junction Flashing Yellows 28/02/2014 at 01:41 #56322 | |
Danny252
1461 posts |
It appears that the Flashing Yellow sequence will trigger at Uddingston Junction even if a train has already passed M170, which holds the FYY aspect - is this another one of Motherwell's undocumented quirks, or should it do the normal reversion to "approach control from red", as occurs at Law Junction?
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| Uddingston Junction Flashing Yellows 28/02/2014 at 05:02 #56324 | |
GeoffM
6282 posts 
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Rules only require the single flashing yellow to be visible for at least 300yds on the approach side of the FY signal, otherwise it reverts to approach control from red. Thus the train can pass a (steady) double yellow and, as long as the (flashing) single yellow is shown before the train reaches 300yds then the (abbreviated) flashing sequence is allowed. In practice they seem to use simple track circuit occupancy, which may be a lot more than 300yds, to determine whether to allow flashing or not - or with the addition of a timer if particularly long. I can't see any difference between Uddingston and Law Jns in this respect. SimSig Boss Last edited: 28/02/2014 at 05:04 by GeoffM Log in to reply |
| Uddingston Junction Flashing Yellows 28/02/2014 at 07:01 #56326 | |
Peter Bennet
5360 posts
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The FY/FYY signals use that standard SimSig signal FY module "tick box". Peter I identify as half man half biscuit - crumbs! Log in to reply |
| Uddingston Junction Flashing Yellows 28/02/2014 at 11:48 #56334 | |
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Danny252
1461 posts |
" said:Rules only require the single flashing yellow to be visible for at least 300yds on the approach side of the FY signalHuh, I was convinced the rules required that the driver saw both FYY and FY. However, after much searching, I've finally found a reference in the rules that does state that seeing only FY in 4-aspect territory is a valid aspect - many of the other sources I've found (including some rules/official documents) either state or imply that FYY-FY-Y is the only valid sequence, and that any deviation from that is not allowed. Last edited: 28/02/2014 at 11:51 by Danny252 Log in to reply |
| Uddingston Junction Flashing Yellows 28/02/2014 at 13:34 #56338 | |
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dwelham313
139 posts |
When routed Down Fast to Down Slow/Down Flyover at Hitchin, the double yellow you receive is incapable of flashing. If the route is set the single yellow begins to flash once the steady double yellow returns to danger, so it's certainly possible to omit the flashing double yellow.
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| Uddingston Junction Flashing Yellows 28/02/2014 at 16:58 #56350 | |
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GeoffM
6282 posts
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I tried to find a reference on the internet but the only source was SSI8003 which I've never seen online. That does mention GK/RT0060 and GK/RT0062 but those don't mention the sighting/distance factors.
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| Uddingston Junction Flashing Yellows 28/02/2014 at 21:11 #56369 | |
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Firefly
521 posts |
Quote:Can confirm that only the flashing single yellow is required to be seen (the inner distant). Not sure about 300yds, I guess that might be an old WR figure or SSP. The current standard NR/L2/SIG/19609 states:- Quote: An inner distant signal shall not commence to flash when the junction signal becomes free to clear if the approaching train has reached the point equivalent to the minimum reading distance (MRD) for the signal. In this case, the junction signal shall revert to MAR control.The point the flashing sequence is inhibited therefore depends on the line speed, structures, etc FF Log in to reply |
| Uddingston Junction Flashing Yellows 28/02/2014 at 22:27 #56372 | |
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clive
2738 posts |
GK/RT0045 issue 3 para 5.2.3.6: "A flashing aspect sequence shall only be displayed when the approaching train is detected to be in a position that is compatible with the required reading time of the junction distant signal that displays the flashing single yellow aspect and one of the following applies: a) The first signal beyond the diverging junction is a controlled stop signal that is either one of the following: i) Displaying an OFF aspect. ii) Displaying an ON aspect and a forward route is set. iii) Displaying an ON aspect at the end of a loop line or platform line where all trains are expected to stop. b) The first signal beyond the diverging junction is an automatic signal. c) The first signal beyond the diverging junction is an isolated distant signal." So it looks like the requirement is the usual 8 seconds. Log in to reply |
| Uddingston Junction Flashing Yellows 01/03/2014 at 02:19 #56384 | |
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Danny252
1461 posts |
Any hints as to why there are the restrictions on controlled signals after the junction? It seems odd to single out controlled signals at danger, whilst allowing an automatic to display any aspect.
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| Uddingston Junction Flashing Yellows 01/03/2014 at 04:21 #56386 | |
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Late Turn
696 posts |
Presumably a response to Colwich - at least if the next signal's an auto, the potential consequences of a SPAD (in terms of the collision risk, particularly conflicting routes) are very much reduced!
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| Uddingston Junction Flashing Yellows 01/03/2014 at 08:27 #56389 | |
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Peter Bennet
5360 posts
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" said:Any hints as to why there are the restrictions on controlled signals after the junction? It seems odd to single out controlled signals at danger, whilst allowing an automatic to display any aspect.It's arranged as per how I was told it worked by someone who worked the box, the point has also been queried in relation to Law Jn too. If someone can come up with the control data that was in place before Motherwell closed then I can change it. Peter I identify as half man half biscuit - crumbs! Log in to reply |
| Uddingston Junction Flashing Yellows 01/03/2014 at 20:56 #56412 | |
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Firefly
521 posts |
Quote:As late turn said. Also consider that a controlled signal "Displaying an ON aspect and a forward route is set." has the same risk as an auto signal because the reason that the controlled signal is displaying ON could be that there's a train in the section ahead, however the route being set prevents anything other than a tail end collision. It's assumed that a driver getting lulled into thinking the next signal will be at proceed will wake up when a Red aspect is sighted and hit the brakes. The train will most likely SPAD but there won't be a head on collision, or a side swipe with a train running at high speed. FF Log in to reply |
| Uddingston Junction Flashing Yellows 01/03/2014 at 22:36 #56418 | |
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TomOF
452 posts |
" said:If someone can come up with the control data that was in place before Motherwell closed then I can change it.Motherwell PSB is still open to the best of my knowledge. We found when researching Carlisle a lot odd conditional reds. They where never marked on the panel and the signallers had to either ask a friendly S&T man what the aspect was showing or wait for an irate call from a driver to find out which signals had them. There must have bit of derogation against standards in both cases. Last edited: 01/03/2014 at 22:36 by TomOF Log in to reply |
| Uddingston Junction Flashing Yellows 01/03/2014 at 23:18 #56423 | |
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Ron_J
329 posts |
" said:Motherwell PSB is still open to the best of my knowledge.Correct. The box will go in two stages; Motherwell North resignalling will migrate panels 1 to 4 to West of Scotland SC in late 2017 (commissioning was scheduled originally for April 2017 but has slipped) and panels 5 and 6 will follow as the Motherwell South resignalling in 2019. It was to be a straight recontrol but asset condition demands a more intrusive approach, with a number of new CBIs as well as many, many new signal structures. Log in to reply |