All,

With the development nearly complete on our impending HO Timber Road Bridge Range, there is one facet that needs sorting & I pose this question regarding double track road overbridges. What track centres do Australian Outline layout builders try to adopt???

This will help in determining the tolerance we use for pile or bent centres both in practice & instruction sheets etc..

While we are aware of NSWGR ruling structure clearances & have perused the NMRA standards, I am not sure whether these hold true in scale practice. Also there are other factors including, rollingstock used, curve radius used ( if applicable ), & of course the existing layout track centres.

Any input would obviously be helpful in determining the best solve to the problem.

For any info on the bridge range please refer to our blog...http://southernline.blogspot.com.au/


Thanks & Regards,

Rod Kelly
Laser Rail Bits

A very personal observation is a lot of people are using peco track as standard and thus track spacing for points and crossovers - it seems. One clue.

track centers vary but a interesting thing to find out.

regards,
David Head

David,

Thanks for your input.  Yes you are quite correct in referencing the Peco benchmark.  This dimension will allow us to be fairly close on track centres for straight track...but track centres on curves are probably our main concern as sometimes the centres are relaxed for rollingstock & radius concerns as does the prototype.  The other issue is hand laid track etc.

I guess the whole issue is an old chestnut & a rhetorical question...but as you stated it will be interesting to find how the local scene addresses this issue.

Rod Kelly

Depending on how the castings are constructed, could you produce two half-bridges with inserts available to cover the gap for a wider spacing?

For example, the basic kit could be three parts - one for each side and a thin centre clip-in bit with the keystones. Then people could buy replacement centres including the keystone, but also a few bricks either side to give the extra width?

suppose best to metion peco track centers would be very wide for aussie centers, state by state too.

not to men tion all the other popular brands, and full size variations.  but you are trying to find a best fit idea, hope it goes welll.

David Head

All,

With the development nearly complete on our impending HO Timber Road Bridge Range, there is one facet that needs sorting & I pose this question regarding double track road overbridges. What track centres do Australian Outline layout builders try to adopt???

This will help in determining the tolerance we use for pile or bent centres both in practice & instruction sheets etc..

While we are aware of NSWGR ruling structure clearances & have perused the NMRA standards, I am not sure whether these hold true in scale practice. Also there are other factors including, rollingstock used, curve radius used ( if applicable ), & of course the existing layout track centres.

Any input would obviously be helpful in determining the best solve to the problem.

For any info on the bridge range please refer to our blog...http://southernline.blogspot.com.au/


Thanks & Regards,

Rod Kelly
Laser Rail Bits

Rod

This could be a can of worms in many ways.   So, railway terms for the distance between tracks were called the 6 foot, that is the distance between the outer rail to the inner rail of the other track, the thing whether it was a true 6 foot or not is not known by me.

As for operating should something happen to a train on double track the fireman was always required to walk on the drivers side of the track for any problems owing to the short space between the two down & up main lines.  If, the walkway on the drivers side was narrow or littered with debri, usually sleepers or fallen trees, rock etc, to walk in the 6 foot was a last resort.

If a train was heard coming in the opposite direction we were to go flat on the ground in the middle of the 6ft, this was deemed sufficient space for safety, it also fitted in with loading gauges.

As for modelling, how many will have the same distances as others?

The man asked what people use, well i use 2.5" track centres around my layout, on straights and curves, it allows me to maintain a consistent separation that doesn't look too rediculous on straights and ample clearance for longer rollingstock on curves and generally, some buffer zone in the event of a derailment to help avoid catastrophy with an opposing movement.

Regards,
Joe.

All,

With the development nearly complete on our impending HO Timber Road Bridge Range, there is one facet that needs sorting & I pose this question regarding double track road overbridges. What track centres do Australian Outline layout builders try to adopt???

This will help in determining the tolerance we use for pile or bent centres both in practice & instruction sheets etc..

While we are aware of NSWGR ruling structure clearances & have perused the NMRA standards, I am not sure whether these hold true in scale practice. Also there are other factors including, rollingstock used, curve radius used ( if applicable ), & of course the existing layout track centres.

Any input would obviously be helpful in determining the best solve to the problem.

For any info on the bridge range please refer to our blog...http://southernline.blogspot.com.au/


Thanks & Regards,

Rod Kelly
Laser Rail Bits

Have a look at the AMRA clearance and track centre standard.

Cheers,

Terry Flynn

AMRA standards http://www.amra.asn.au/standards.htm

HO regular track I prefer an absolute maximum of 50mm, I'd bring it back to several mm less where possible. The HO tramway I have just laid had (code 83) track centres down to 40mm, I had to modify points to achieve this, including getting a full scissor scratch built. Properly massive curve radii are involved so I kept a fairly strict 40mm centre, looks SIGNIFICANTLY better than code 100 track spaced to 50mm.

personally I like 50mm mainline to mainline, and mainline to yard, to allow space for signalmasts etc. within yards I try to go down to 45mm for those yards off the mainline.

We used 45mm centers on Murranbilla, which we never had a problem with - only problem  was placement of  signals between the mainline and yard.

Regards,
David Head

Track centres on a model railway largely depend on what you are going to run on the tracks. Short  4 wheeled vehicles can have almost prototypical track spacings, but long modern wagons need a lot more space between the tracks if you dont want them hitting one another. So it is really a can of worms everyone has their own pet method of getting the actual track centres , so it is not as easy to just state xxmm and be right.

Even Peco track centres are not good enough sometimes and curves in flextrack etc have to be wider than what is recommended.

Greg Edward's NSWR Track Data Sheet manual lists the following for prototype (you know 1:1) track centres in NSW

Main Lines - 11'-3"
Crossing Loops - 12'-0"
Sidings and other tracks - 13'-0"
Refuge Loops and other tracks - 13'-0"

In regards to "clearance from structures" it suggests referring to the "Minimum Structure Gauge" showing clearances from a tangent (straight) track

It goes on to discuss and provide a formula for track centre "widening on curves" and "transitions before curves" whether or not this information complies with the AMRA standard remains to be seen. Maybe the HUB cars have an unusually long overhang when their bogies try to go around corners?

But given that the information sourced for the Track Manual came from the Railway Archives, I tend to favour it as a starting point

Hope this helps - "it takes many types to run a railway"

Regards,

Catchpoint

G'day gang,
I use two and a half inches track centres.
It may be wider than prototype but gives you room to place signals, track side scenery and gives clearance for crossing trains.
I must state that I run single track main line and the only place that I need track centres are where my passing loops run around curves and there are plenty of curves on my layout.
As a thought, and please don't start a war over what I am saying, would it not be hard to bring into play prototype spacing as the overhang on our models is far greater than what you get in the full size world.
I use what I need to get clearence between vehicles on a curve. Is that not all you should be aiming for

It just got the better of me and i went down and remeasured mine, and while i thought i was using 2.5", its actually 2.25" or around 54mm.

This thread has been fairly well spammed with useless posts about "can of worms" type comments and "depends on this or that" and "protoype and AMRA standards" that contribute zero to Rods dilema. AMRA standards don't even come into tha arguement as a standard only works if people use them and regarding prototype standards, they might exist but really, nothing is standard in the real world of railways, especially in the case of track centers where crossing loops are concerned.

Now surely there are more then 4 layout owners on this board to give Rod an actual "number/meaurement" that they use on their layout and perhaps even why, rather then this nonsense spam posts of "well it'll depend on this or that", "hard to say" etc. Give the man the information he wants and spare us the waffle, all of us already know.

Cheers,
Joe.

All,

Just a word of thanks for the replies already posted & to Joe for clarifying the point of the original post.  

While setting the  "Terms Of Reference" regarding any post will certainly limit the responses, the question was  aimed at what practices were being used by clubs, individual layout owners & those planning a layout.  It is certainly a relevant question & one which we need to have a firm understanding of for kit design going forward.

I am aware of all of the standards set down by local & overseas modelling organisations & prototype government owners but these appear to be seldom followed to the letter & in reality only source documents.  During extensive reasearch that is carried out for all of our kits it is evident that the same can be said for "General Arrangement" drawings of railway infrastructure & certainly the "as built"  examples sourced from those same drawings vary from location to location  depending on many factors.

In relation to prototype trackside clearances...One fact is hard to ignore...If all of the rules of yesterday were followed we would have had no reason for regular profile trains.

Anyway thank you again to all who have taken the time to reply & I look forward to being able to table the results.

Regards,

Rod Kelly

Rod  i think we all forgot  that the bridge is straight, thus making any  "S" bend not a concern. So best of luck with the product.

Regards,
David Head

This matter would not even be raised by a US prototype manufacturer as they would just blindly follow NMRA standards and ignore the prototype.  We should be thankful that a manufacturer is looking at prototype diagrams and asking a valid question.  I would like to say that the answer should be the prototype but the commercial reality dictates PECO.

Sorry to Wrongroad/Joe, I didn’t respond before because all indications are that this is a NSWGR prototype (I model VR) and the discussion is about double track main lines and mine is single track.  Maybe when LRB get to VR timber structures I will comment more.

Mark

This matter would not even be raised by a US prototype manufacturer as they would just blindly follow NMRA standards and ignore the prototype. We should be thankful that a manufacturer is looking at prototype diagrams and asking a valid question. I would like to say that the answer should be the prototype but the commercial reality dictates PECO.

Sorry to Wrongroad/Joe, I didn’t respond before because all indications are that this is a NSWGR prototype (I model VR) and the discussion is about double track main lines and mine is single track. Maybe when LRB get to VR timber structures I will comment more.

Mark

No need to apologise to me Mark. Like you i think its awesome a manufacturer is asking for punters input and guidence, but frustrated by the thread spammers.

Cheers.

Mark, All

While this response is a bit off string...I would never rule out Victorian lineside structures.  The sheer volume of sales of our NSW tank stand as well as the others, has encouraged us that we are heading in the right direction & people are warming to what we are producing.  The truth of the matter is that NSW prototype info is easier to procure, I am familiar with it and where possible/required I can spend a couple of days actually crawling ( and dribbling ) all over the intended subject with camera & tape measure in hand in most cases a stone's throw from home.  The most important aspect is available time...I have a head full of ideas re NSW structures but lack the main commodity...TIME

To pose a dumb question(s) to our Southern Cousins... Are there structure diagrams of Victorian Lineside Structures of the same ilk as the Greg Edwards range and the other question being, what does the Victorian market lack in terms of what the modeller wants???

Hmmmm.... Now WHO is getting off subject!!!

Regards,
Rod Kelly

Mark Bau's site  is the one to go for as he has original diagrams of all manner of VR Structures as PDF's on it (victorianrailways.net I think). As I recall the VR was mainly into simple flat girder bridges.

Iain,

Whoa...i should not have gone to that site.  Very impressive.  Thanks for the info.

Will go to school here.

Rod Kelly

Mark, All

................. Are there structure diagrams of Victorian Lineside Structures of the same ilk as the Greg Edwards range and the other question being, what does the Victorian market lack in terms of what the modeller wants???

Regards,
Rod Kelly

Rod


http://www.victorianrailways.net/infastuct/infastructhome.html

Have a look at Mark Bau's web site. It has many VR plans including bridges and typists tables!

Mark

It just got the better of me and i went down and remeasured mine, and while i thought i was using 2.5", its actually 2.25" or around 54mm.

This thread has been fairly well spammed with useless posts about "can of worms" type comments and "depends on this or that" and "protoype and AMRA standards" that contribute zero to Rods dilema. AMRA standards don't even come into tha arguement as a standard only works if people use them and regarding prototype standards, they might exist but really, nothing is standard in the real world of railways, especially in the case of track centers where crossing loops are concerned.

Now surely there are more then 4 layout owners on this board to give Rod an actual "number/meaurement" that they use on their layout and perhaps even why, rather then this nonsense spam posts of "well it'll depend on this or that", "hard to say" etc. Give the man the information he wants and spare us the waffle, all of us already know.

Cheers,
Joe.

Hey Joe,

Have you actually read the AMRA clearance and track centre standard? What is the problem with a standard that provides practical advice to layout builders and in this case a kit manufacturer. Not only does it give the minimum track centre distances for various situations, but it also gives the structure height and width dimensions, something your post does not provide.

The AMRA standard refers to minimum track centres and minimum structure clearances. If you do not comply with it you will have a high chance of models side swiping each other. A geometric fact. Unfortunately you cannot use the prototype clearances because the model wheel to rail clearances and axle end play are over scale. The only exceptions are the few modellers using 'exact' standards like P-87. The AMRA standards take this fact into account and produce a practical real world solution.

My layout complies with the AMRA clearance and track centre standard and most layouts I have seen comply with this standard. So you use 54mm track centres. According to the AMRA standard for NSW prototypes, your track centre distance complies as well. I'm glad you are following the AMRA standard, no doubt you have no clearance problems.

Terry Flynn.

AMRA standards http://www.amra.asn.au/standards.htm

G'day LaidlayM,
Mate I am with Joe on this, no need to apologise at all.
The question was asked and answered by both Joe and myself as to what we do on our layouts.
As I said, I run a single main line but I was going off what centres I use on my crossing loops.
Regards and respect
Daryl

For the OP my track centres conform to two strips of TrackRite underlay foam laid side by side whether that've straights or curves. I think it's about 55mm centres, from memory. If my trains run okay and look good then I don't care  for AMRA standards.