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Boom gate failures force indefinite shutdown (Melbourne, Aust) 02/04/2015 at 02:16 #70642 | |
maxand
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Quote:The Stony Point rail line (Melbourne, Australia) is closed indefinitely following a series of safety breaches in which boom gates failed to drop for an approaching train.Link Interesting that their solution centres around axle counters, as recently discussed here. Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 02/04/2015 at 04:24 #70643 | |
ozrail
![]() 197 posts |
Isn't the Labor government going to get rid of all the lever crossings in Melbourne? I can think of only two in the whole of Sydney.
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Boom gate failures force indefinite shutdown (Melbourne, Aust) 02/04/2015 at 06:46 #70647 | |
BarryM
![]() 2158 posts |
" said:Isn't the Labor government going to get rid of all the lever crossings in Melbourne? I can think of only two in the whole of Sydney.Oz, you are kidding me! I know of 15 level crossings in Sydney. FYI! 8 on Richmond line. 3 on the South. 1 at Clyde. 2 on Sandown line. 1 at Mascot. E&OE Barry Barry, Sydney, New South Wales, Australia Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 02/04/2015 at 07:14 #70648 | |
kaiwhara
![]() 587 posts |
" said:" said:Still a lot less than Auckland, New Zealand. Auckland has double that number of crossings on the Metro Network, but the route mileage of Sydney's Metro Network is 15 times that of Auckland...Isn't the Labor government going to get rid of all the lever crossings in Melbourne? I can think of only two in the whole of Sydney.Oz, you are kidding me! I know of 15 level crossings in Sydney. Sorry guys, I am in the business of making people wait! Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 02/04/2015 at 09:09 #70652 | |
ozrail
![]() 197 posts |
Sorry didn't put much thought into my comment. Now I'm going to have to look them all up. Serves me right.
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Boom gate failures force indefinite shutdown (Melbourne, Aust) 02/04/2015 at 14:04 #70663 | |
clive
![]() 2766 posts |
" said:Quote:The standard approach in the UK is that AHBs are triggered by two separate mechanisms, normally a track circuit and a treadle. Depressing the treadle will trigger the track circuit - it is often wired in series with the track circuit relay, so that no extra logic is required. This way, when a train reaches the strike-in point it will start the crossing sequence even if the rails are covered in rust. Log in to reply The following user said thank you: BarryM |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 02/04/2015 at 16:33 #70667 | |
Jersey_Mike
![]() 250 posts |
Quote:The Stony Point rail line (Melbourne, Australia) is closed indefinitely following a series of safety breaches in which boom gates failed to drop for an approaching train.First, do they not have the money to purchase a red flag to flag the crossings...or just have the trains approach each crossing prepared to stop? Second when this problem cropped up on the PRSL Cape May branch (see above photo) in the waning years of the service, one solution to deal with rusty rail conditions was to weld the equivalent of rumble strips on the track made out of some corrosion resistant material. When the train went over the welded bits of metal that would trigger the crossing protection even if the rail was otherwise rusted over. Last edited: 02/04/2015 at 16:34 by Jersey_Mike Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 06:07 #70698 | |
Mattyq
![]() 259 posts |
" said:I have seen this done in Queensland, Australia. A stainless steel welded zigzag strip on the rail head of rarely used tracks to ensure track circuit conductivity is maintained. I'll try and procure a picture. Not fat ..... fluffy!! (G Iglesias) Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 08:28 #70701 | |
kbarber
![]() 1723 posts |
" said:" said:I have seen this done in Queensland, Australia. A stainless steel welded zigzag strip on the rail head of rarely used tracks to ensure track circuit conductivity is maintained. I'll try and procure a picture. I think they call it 'eutectic weld'; common in the UK at the stop block end of terminal platforms and I've ssen it on some rarely-used crossover roads on the UndergrounD. Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 12:42 #70716 | |
maxand
![]() 1637 posts |
Thanks for the interesting feedback. Clive wrote in post #6: Quote: The standard approach in the UK is that AHBs are triggered by two separate mechanisms, normally a track circuit and a treadle. Depressing the treadle will trigger the track circuit - it is often wired in series with the track circuit relay, so that no extra logic is required. This way, when a train reaches the strike-in point it will start the crossing sequence even if the rails are covered in rust.I had not heard of treadles before this, except in connection with foot operated sewing machines and spinning wheels. It seems they are only found associated with AHB crossings, as they are triggered by the train (see here for a nice summary of types of crossings) but I am still confused as to how they work. Are they actually struck (depressed) by the train? If so, isn't there a high risk of damage to them? This thread from another forum has some nice photos of what I assume are treadles, but this is not confirmed in the thread. I have found it difficult to obtain specific information on treadles. Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 13:15 #70718 | |
AndyG
![]() 1842 posts |
Pic of a treadle, and block joint, adjacent to an AHB level crossing.![]() Post has attachments. Log in to view them. I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Log in to reply The following users said thank you: TimTamToe, Steamer, maxand |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 13:22 #70719 | |
Steamer
![]() 3958 posts |
" said:Pic of a treadle, and block joint, adjacent to an AHB level crossing.Just to confirm, is the treadle operated mechanically by the wheel flange? "Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q) Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 14:22 #70722 | |
AndyG
![]() 1842 posts |
Yes, a Z shaped arm is depressed by the wheel flange. Another shot at a nearby location, the treadles are in advance of the 'protecting' (automatic with ER control) signal, I assume to lower the AHB barriers in case of a SPaD. The actuating arm is just visible. ![]() Post has attachments. Log in to view them. I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Log in to reply The following users said thank you: TimTamToe, Steamer, maxand |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 15:04 #70725 | |
Jersey_Mike
![]() 250 posts |
Why are treadles preferable to audio frequency track circuits?
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Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 15:23 #70726 | |
Danny252
![]() 1461 posts |
If a DC track circuit has already failed to detect the train, why would an AC track circuit do any better?
Last edited: 03/04/2015 at 15:23 by Danny252 Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 03/04/2015 at 16:01 #70729 | |
Jersey_Mike
![]() 250 posts |
" said:If a DC track circuit has already failed to detect the train, why would an AC track circuit do any better?The line in the photo is already track circuited. If train detection were a problem...it would be a bigger problem. Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 04/04/2015 at 08:28 #70745 | |
kbarber
![]() 1723 posts |
" said:Why are treadles preferable to audio frequency track circuits? Not sure what (if any) AF TCs are authorised for use over here, but in any case treadles for level crossing strike-in have been in use since the early 1960s, are simple and robust and have a very high degree of reliability; if it ain't bust, don't fix it. Where lines are track circuited, treadles are normally provided in addition to the track circuit. One is to increase reliability to off the scale... the one thing you don't want is the 1-in-10 million wrong side failure to affect an AHB on a 100mph running line. It's the old S&T engineer's preference for belt and braces (and a piece of string to make sure). The other, perhaps more realistic, reason is that certain vehicles (mainly civil engineers' on-track machines) cannot be relied upon to operate track circuits. They run under special arrangements set out in the Rules & Regs but you still need them to operate level crossing strike-ins, for which a treadle is ideal. Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 04/04/2015 at 09:03 #70746 | |
Firefly
![]() 521 posts |
Quote:Depressing the treadle will trigger the track circuit - it is often wired in series with the track circuit relay, so that no extra logic is required.I have seen that around the network in some very old installations but it's certainly not standard. These days the treadle controls and track controls are summated into the level crossing strike in circuits along with some other controls to inhibit the strike in when trains are going away from the crossing. The circuitry also needs to detect if a treadle has a broken arm and is no longer functioning. Therefore pressing the treadle would not cause the track circuit to show occupied on the panel. I've seen treadles used to re-enforce track circuits on the Swindon Area. They've been installed on the bi-directional crossovers which are rarely used and therefore suffer from rusty rails. Other crossovers which don't have treadles have the zinc strip referred to earlier, however that strip is extremely expensive. Quote: Just to confirm, is the treadle operated mechanically by the wheel flange?Yes some treadles have single arms which will operate their contacts for trains going in either direction. Some treadles have double arms. There are 3 types of double arm treadles. AB - Only operates contacts for trains going in a single direction BA - Only operates contacts for trains going in a single direction (exactly the same as above but used for the other rail) ABBA - Operates one set of contacts for a train going in one direction and a different set of contacts for a train going in the opposite direction. When we use treadles for level crossing strike-ins they're always duplicate (one each side of the track). As mentioned above the circuitry also proves that the treadle has operated and therefore the arm hasn't snapped off. The treadle arms are damped and take about 7 seconds to return to the normal position, therefore they are not subject to being struck down by every wheel flange, the first wheel flange strikes them down and the remaining wheels just keep them in the lowered position. FF Log in to reply The following users said thank you: Steamer, TimTamToe |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 04/04/2015 at 09:56 #70747 | |
AndyG
![]() 1842 posts |
FF, or anyone else that knows:- Is the treadle contact set up to be NC (normally closed), to prove the integrity of the wiring when dormant, and activates when it goes open circuit? I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 04/04/2015 at 10:47 #70748 | |
Firefly
![]() 521 posts |
They have normally open and normally closed contacts. The crossing strike in function to lower the crossing uses the normally closed contacts. The crossing reset function on the treadles at the crossing which prove the train has passed the crossing use the normally open contacts. FF Log in to reply The following users said thank you: maxand, AndyG |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 08/04/2015 at 11:16 #70858 | |
Jersey_Mike
![]() 250 posts |
" said:" said:Mechanical items usually require both inspection and preventative maintenance. Also with treadles you need some mechanism so that random students or animals or whatever can't just trigger the crossing gates. Seriously, having a "lower crossing gates here" button that isn't in a locked box is an attractive nuisance.Why are treadles preferable to audio frequency track circuits? " said:
I'd suggest louder horns ![]() " said: Can't they just slow down and occupy the highway crossing with care? Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 08/04/2015 at 12:48 #70859 | |
postal
![]() 5216 posts ![]() |
" said:" said:Two nations divided by a common language." said:Mechanical items usually require both inspection and preventative maintenance. Also with treadles you need some mechanism so that random students or animals or whatever can't just trigger the crossing gates. Seriously, having a "lower crossing gates here" button that isn't in a locked box is an attractive nuisance.Why are treadles preferable to audio frequency track circuits? “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 |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 14/04/2015 at 13:17 #71055 | |
kbarber
![]() 1723 posts |
" said:" said:" said:Mechanical items usually require both inspection and preventative maintenance. Also with treadles you need some mechanism so that random students or animals or whatever can't just trigger the crossing gates. Seriously, having a "lower crossing gates here" button that isn't in a locked box is an attractive nuisance.Why are treadles preferable to audio frequency track circuits? As I said, they work to a very high level of reliability. 'Nuff said really. " said: " said: Not a lot of use if a crossing's failed wrong-side. If the crossing isn't operating correctly there's be nothing to stop road traffic continuing to run until the train is far too close for evasive action. 100mph doesn't allow that sort of (desperately unsafe, in my view) expedient. " said: " said:Can't they just slow down and occupy the highway crossing with care? They already cause enough disruption to the timetable without being cautioned over all level crossings. Yet again Mike, it ain't bust so there's no need to fix it. Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 14/04/2015 at 14:56 #71063 | |
Jersey_Mike
![]() 250 posts |
" said:You put up a sign warning road users of the danger of high speed trains (in that case 110mph). Active warning devices should not relieve the road user of their responsibility to be on the lookout for rail traffic...which naturally should have the right of way B) . BTW as much as I love that photo I'm not cherry picking. Log in to reply |
Boom gate failures force indefinite shutdown (Melbourne, Aust) 14/04/2015 at 15:42 #71065 | |
Steamer
![]() 3958 posts |
Your idea assumes that the track is straight and that road users are responsible. Unfortunately, the number of accidents and near misses on the road, in addition to the current amount of level crossing abuse, is strong evidence that many of them are not. It'll take a heck of a culture shift before I'd be happy with cars pulling out onto railway lines relying only on the car driver to check the line is clear.
"Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q) Log in to reply |