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| Forth Bridge restrictions 11/04/2010 at 10:18 #1104 | |
Peter Bennet
5402 posts |
I understand that there are restrictions on freight trains crossing the bridge at the same time- my notes only refer to Class 7 is that it, or are there others? Peter I identify as half man half biscuit - crumbs! Log in to reply |
| Forth Bridge restrictions 11/04/2010 at 10:18 #8373 | |
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Peter Bennet
5402 posts |
I understand that there are restrictions on freight trains crossing the bridge at the same time- my notes only refer to Class 7 is that it, or are there others? Peter I identify as half man half biscuit - crumbs! Log in to reply |
| Forth Bridge restrictions 11/04/2010 at 11:49 #8378 | |
postal
5265 posts |
Peter Network Rail Rules of the Plan for 2010 (at http://www.networkrail.co.uk/browse documents/Rules Of The Route/Outrotp10/sc10p.pdf) include this statement on Page 82 "Dalmeny Restriction Freight trains carrying a 7Gxx headcode must not be timed to pass another freight train on the opposite line on the Forth Bridge." Not totally helpful as the RotP impose a timetabling constraint rather than laying down an operational specification. The Sectional Appendix dated 1 April 2009 gives the speed restrictions on the bridge but the only operational note states "The lines over the Forth Bridge are capable of being worked in either direction by special arrangement (see Local Instructions)" I suppose for SimSig purposes you need to decide whether the RotP stipulation is in effect an operational instruction then decide how that is handled; manually by the duty signaller (with a penalty for breaking the rule) or written into the interlocking / ARS logic? Presumably those that know will be able to advise on the real-life situation. Incidentally the RotP for all lines are available on the Network Rail website and include lots of useful information for timetablers about minimum time allowances and headways as well as a listing of platform lengths. JG “In life, there is always someone out there, who won’t like you, for whatever reason, don’t let the insecurities in their lives affect yours.” – Rashida Rowe Log in to reply |
| Forth Bridge restrictions 13/04/2010 at 11:31 #8461 | |
Ron_J
331 posts |
From the box special instructions: Forth Bridge Working of freight trains The following instructions apply only to those freight trains carrying a 7Gxx headcode. You must not allow a freight train carrying a 7Gxx headcode to pass another freight train on the opposite line on the bridge. Down direction Before you clear signal Y653 (Down Winchburgh) or Y651 (Down Fife) for a freight train to proceed onto the bridge, you must make sure that:
*no signals have been cleared for a freight train to proceed from Inverkeithing Central Junction towards the bridge. Normal working must not be resumed on the Up Fife line until the freight train concerned has passed clear of track circuit 795 (North Queensferry) Up direction Before you clear a signal for a freight train to proceed from Inverkeithing Central Junction towards the bridge, you must make sure that:
*no signals have been cleared for a Down freight train to proceed towards the bridge. Normal working must not be resumed on the Down Fife line until the freight train concerned has passed clear of track circuit 792 (Dalmeny) Log in to reply |
| Forth Bridge restrictions 13/04/2010 at 12:09 #8462 | |
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Peter Bennet
5402 posts |
Ok, thanks, not sure if I can do anything about testing for a route set for a freight train as that could mean looking back some distance which will get complicated but testing for a 7G and a Class 4,6,7,8 in the 'no-go' zone and imposing a penalty should be do-able. I'm guessing that 7Gs are the Longannet coal trains so only work down which makes life easier. Some XC trains have a class 9 ID so that needs some consideration. Maybe I can just test for the freight box being ticked in the timetable. Peter I identify as half man half biscuit - crumbs! Log in to reply |
| Forth Bridge restrictions 13/04/2010 at 12:42 #8464 | |
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bill_gensheet
1413 posts |
The rule for a 7Gxx does not take account of a 'heavy' train heading south, such as loaded coal or perhaps a long ballast, meeting a similar one. Would the test be better (or easier) if testing 'freight v slow' acceleration type and another freight type ? In the 2006 version of currently the only heavy trains are the Hunterston - Longannet MGR's, and I'd expect that any train over half the Forth bridge design limit would have an additional restriction placed on it. As far as the route setting restriction goes, I read that has a good way of ensuring that you don't end up with two heavy trains on the bridge. Otherwise you'd be taking chances that one might slow or fail and be faced with having to put back on the other. Bill Log in to reply |
| Forth Bridge restrictions 13/04/2010 at 13:21 #8465 | |
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AnyFile
101 posts |
From what is written in the special instruction this means that you can to "park" the train into the loop between Dalmeny Jn and Dalmeny station. Not only I can not understand the reason for that, but this also make things very difficult to deal with if you have a passenger train behind the freight. Log in to reply |
| Forth Bridge restrictions 13/04/2010 at 13:40 #8466 | |
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Late Turn
699 posts 
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The restriction in the Special Instructions - whatever the reason for its presence - will almost certainly not be considered in the conditions for setting a route. The application of the Special Instructions by the Signalman should be sufficient to ensure that the need to 'put back' on a freight to prevent it meeting a 7Gxx freight on the bridge is avoided - perhaps the ARS is programmed to require routes towards the bridge to be set manually for 7Gxx trains, but it's unlikely that the locking would prevent such a route being set.
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| Forth Bridge restrictions 14/04/2010 at 10:23 #8491 | |
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Forest Pines
525 posts |
AnyFile said:From what is written in the special instruction this means that you can to "park" the train into the loop between Dalmeny Jn and Dalmeny station.I wouldn't be surprised if the types of train that the restriction applies to were too long for Dalmeny down loop in any case. I was once on board an HST that was stopped in Dalmeny down loop, and my recollection is that it was too long to fit properly in the loop, as far as I could tell. (this was a late-running ECML service that had got stuck behind a Fife Circle local, so the signaller allowed the HST forward into Dalmeny loop while the local was doing its station stop.) Presumably the holding points in the instruction - approaching Dalmeny Jn and approaching Inverkeithing Central Jn - are deliberately chosen to minimise the chances of getting a passenger train stuck behind a waiting freight. There are several other potential factors too, though: the difficulty of restarting a heavy up freight on Inverkeithing bank, for one; and does Jamestown Viaduct have a similar weight restriction to the Forth Bridge? Log in to reply |
| Forth Bridge restrictions 14/04/2010 at 10:34 #8493 | |
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Late Turn
699 posts
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Incidentally, the wording "before you clear signal Y653 (Down Winchburgh) or Y651 (Down Fife) for a freight train to proceed onto the bridge, you must make sure that..." seems a little ambiguous with respect to the point that Anyfile raises - if a route is set from 651 or 653 to 657 in the Down Passenger Loop, then you've not cleared either signal for a train to proceed onto the bridge. It's interesting to note that there's no specific restrictions (at least in that extract) on standing such a freight in the loops at Dalmeny or signalling one onto the bridge from there.
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| Forth Bridge restrictions 14/04/2010 at 19:30 #8511 | |
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AnyFile
101 posts |
Perhaps the reason for not considering the loop is that a coal train or a fright train does not usually fit into the loop (at least the 7G?? trains in the standard timetable in the simulation do not fit into the loop). Log in to reply |
| Forth Bridge restrictions 14/04/2010 at 19:55 #8513 | |
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AndyG
1842 posts |
Dalmeny DPL is only 230m long. All the loop lengths are now listed within the manual.
I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Log in to reply |
| Forth Bridge restrictions 14/04/2010 at 21:50 #8517 | |
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bill_gensheet
1413 posts |
I think the Longannet coal circuit should be loco plus 24 HAA which was top limit over the bridge IIRC Loaded bogie hoppers were never allowed, hence the interest in opening access via Alloa. Bill Log in to reply |
| Forth Bridge restrictions 04/05/2010 at 10:06 #8950 | |
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Osprey
35 posts |
The Hunterston-Longannets were 27 HAAs for a long time.This was increased to 29 HAAs and not that long before Alloa reopened and they went over to HTA wagons Im sure 32 HAAs was the limit as some work had been done on the bridge and now the issue was the length of the run-round loops at Dunfermline Townhead.The headcodes were all 7GXXs from the time that the 45mph restriction was slapped on loaded HAA wagons after the derailments involving these wagons at Sanquar and Kirkconnel,unfairly in my opinion as the Sanquar mishap was due to a collapsed culvert and Kirkconnel the driver was speeding.Later this restriction was eased to 55MPH on selected lines of which Polmont to Winchburgh Jn was one.
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| Forth Bridge restrictions 06/05/2010 at 01:17 #8992 | |
BarryM
2158 posts |
AndyG said:Dalmeny DPL is only 230m long. All the loop lengths are now listed within the manual.Andy, could you update the platform lenghts in Wiki? I thought this had been done earlier. Perhaps it is on Peter's to-do list. TIA BarryM Barry, Sydney, New South Wales, Australia Log in to reply |
| Forth Bridge restrictions 06/05/2010 at 02:52 #8997 | |
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AndyG
1842 posts |
Have put some info on that I had, but will need PeterB to fill the gaps in.
I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Log in to reply |