Irish Standard for Clearances to Structures Modelling Dimensions

[eugenepfox]

Please advise if there exists anywhere  a schedule of clearances for scale 4mm = 1 Foot ( Ratio I:76.2) setting out lateral and headroom clearances to structures based on Irish Railways practice. 

I am aware of American and European modelling standards for HO scale (Ratio1: 87.1) and also the BRMSB standards for Platforms, Buildings and Bridges.

In the USA double stacking of containers on rail bogies is commonplace as is double decker trains in Europe.

As neither of the above could operate in Ireland the adoption or reconfiguration of American and European modelling standards would not be appropriate.

I would welcome any information or views on this matter.

[DiveController]

Not sure if this is helpful maybe appendix 3 which you could convert to imperial feet and then scale to  4mm

About 304.8 mm to a foot

http://www.irishrail.ie/media/ie_2018_network_statement_(final_version).pdf

This seems to be the standard going forward not sure if it is historically prototypical 

Edited October 13, 2018 by DiveController

[Broithe]

38 minutes ago, DiveController said:

Not sure if this is helpful maybe appendix 3 which you could convert to imperial feet and then scale to  4mm

About 304.8 main a foot

http://www.irishrail.ie/media/ie_2018_network_statement_(final_version).pdf

This seems to be the standard going forward not sure if it is historically prototypical 

As it says, due allowances must be made on curves - and these allowances will need to be rather greater in a model situation, with rather tighter curves.

[Broithe]

In model terms, I'm not sure that there's a reliable alternative to gently running a selection of stock around and adjusting obstructions as they are found, although pre-planning will reduce the work greatly.

Curves are the big issue.

Some modern locos can have big overhangs at the front (Pendelinos, etc), though Ireland isn't greatly afflicted by that sort of thing.

Even in the real world, people get caught out by standards. On the Big Island, Network Rail has been known to grind off platform noses as a result of new stock coming into service.

[DiveController]

Have to agree with Broithe. You can certainly have prototypical distances between your widest model and line side structures provided the is no curve within one model length of the start/end of any line side structure. If there is, then the model will be angled towards that structure on the approach to it and you going to need larger clearances. If you have a very large layout with prototypical curves (doubt few or anyone has this luxury on a model layout) you'll be fine. If not you'll want to run your 201 locomotives and MK3/4 stock round slowly to ensure you have sufficient clearances and then then allow a bit if there is any wobble due to speed/imperfect track. The same can be said for the loading gauge remaining within tunnel entrances etc

Edited October 13, 2018 by DiveController

[eugenepfox]

Thank you all for taking the time to respond and for the information supplied.

The reason for my enquiry was to try to establish if there was a similar schedule of dimensions set out for Ireland as the BRMSB set out for standard gauge railways for Platforms, Buildings and Bridges.

If you watched the model railway challenge programme on Channel 5 on Friday evening you would have seen that one of the teams had to realign a section of curved track as coaches on concentric curves collided with each other due to inadequate clearances being provided.

American and European standards set out requirements for curved tracks. I am not aware of any OO gauge standards available for curved track!

The  BRMSB for dimensions for Platforms, Buildings and Bridges as set down for standard gauge railways are not I believe appropriate for models of Irish railways due to the fact that Irish prototype coaches were wider that their standard gauge counterparts.

For example the widest coach used in Ireland were the Park Royals which had a maximum width of 10 ft 2 in  being 8 in wider than the standard coaches used on standard gauge.

I fully appreciate the point about clearances having to be increased to cater for curved and canted track and also vertical curvature.

I believe the vehicle (in revenue earning service) with the greatest distance between bogie centres are the pocket wagons with a bogie centre distance of 17000 mm.

I purposely stated revenue earning service to exclude departmental stock such as a ballast cleaner or the like

The standard distance between bogie centres for Intercity stock is 16000 mm and for Suburban / Commuter stock is 14100 mm approximately.

Intercity stock generally has the passenger access doors at the ends of the vehicles which can be problematic for stepping gaps when the platforms are curved e.g., Cork where as Suburban / Commuter stock generally have the (wider) passenger access doors at or near the bogie centres to minimise the effects of centre and end throw when platforms are curved.

On a section of curved track a vehicle will need additional clearance to cater for the centre throw (overhang at the middle of the vehicle) and end throw (overhang at the ends of the vehicle).

The European standard for model railways uses a value equal to twice the centre throw to widen the interval between tracks. So following the same logic this would equate to a vehicle overall length of just over 24 metres which is a little longer than any vehicle currently in use in Ireland.

Mention has been made of the "big overhangs at the front" and I believe that ICRs have an overhang from bogie centre to cab end of 4000 mm, so the maximum end throw such a vehicle would generate is the same as a vehicle with an overall body length of 4000 + 16000 + 4000 = 24000 mm as stated above. 

On a section of curved track the interval between the tracks must be increased by an amount equal to the sum of the end and centre throws in order to preserve the clearances.

Similarly if there is a platform on a curved track, the lateral clearance needs to be increased by an amount equal to the end throw or the centre throws in order to preserve the clearances.

Depending on whether the platform is on the inside or outside of the curve. Allowances for the effects of cant must also be made.

I apologise if the above is long winded, but as someone who worked in 1 to 1 scale for over 40 years and am how hoping to build an OO scale model railway using RTR Irish equipment I am anxious to get it right first time!!

In due course, if there is a desire for it, I will post details of the standards I have adopted (together with the reasoning for same) for the benefit of the group.

I would only be setting out recommendations for the area above rail level and many recommended dimension will be specified from track centre line rather than a rail, as this will suit people who use 16.5 mm track for RTR stock and also people who have adopted 21 mm as their standard .

Vertical clearances will of course be relative to the top of the rail.

It is my belief that RTR stock has wheels compliant with both European (and American standards) and are designed to negotiate a minimum radius of 438 mm (R2 in sectional track). 

I look forward to any further views and in particular if an Irish version of the BRMSB standards for Platforms, Buildings and Bridges would be useful to the group.

Thank you for taking the time to read this post and should need any clarification etc. please just ask.

[DiveController]

Er, if you has stated you had all this info to hand, I'd probably not have bothered to spend time searching for information I thought you might need

[eugenepfox]

Apologies if my question has caused confusion. For information I attach an extract from a now out of print Graham Farish Handbook (scale OO gauge)
and the 2008 August issue of Model Rail which illustrates the British version of what I was trying to find relative to Irish practice. 

I am researching the topic and will share my work if anyone is interested but what I am trying to establish is if the work has already been done by others.

[Colin R]

A few years ago I saw a copy of Jane's World Railways in the local Library and it had (at the time) all the then current details of track and clearance details of just about all the railways of the World. It might be worth trying to find a copy.

 

Colin 

[Mayner]

The current IE Loading and Structure gauge is detailed in Appendix 3 of the IE 2018 Network Statement http://www.irishrail.ie/media/ie_2018_network_statement_(final_version).pdf. 

As far as I know the British Railway Modelling Standards Bureau (BRMSB) was an industry body that has long ceased to exist. The BRMSB standards were developed following WW11 in an attempt to develop common wheel and coupler standards, but the Bureau did not have the same level of influence as the National Model Railroaders Association (NMRA) in the States. At the time major manufacturers like Hornby, Trix and Tri-ang preferred to maintain their in house standards in order to maintain market share and competitive advantage.

The "4mm & 7mm scale societies" in the UK may have developed Loading and Structure gauges for their specific areas of interest. The EM Gauge Society developed a table of Standard Dimensions for 4mm scale including a typical British loading gauge and structural clearances based on the "Model Railway Handbook 7th Edition  https://www.amazon.co.uk/Model-Railways-Handbook-Railway-News/dp/B001G888TK & information in Railway Modeller and Railway Engineer.

British and Irish railway companies tended to develop and establish loading and structure gauges in isolation, the Great Northern section of IE still has a more restricted loading gauge than other sections of IE despite a programme to increase clearances in the 1990s.

 

 

[eugenepfox]

Thank you Colin R and Mayner. 

I am hoping to produce an Irish version of model standards dimensions andclearances for 4 mm scale as I am planning to start constructing a model railway shortly.

I am using RTR models on 16.5 mm track.

Do you think thereis merit in makng the information available to / publishing it on this site for everyone.  

Thank you, Eugene

[StevieB]

Working in 4mm, I simply add 1mm in either side to take account of the 6.5 inches difference in track gauge. Seems to work ok.

Stephen

[Mayner]

1 hour ago, StevieB said:

Working in 4mm, I simply add 1mm in either side to take account of the 6.5 inches difference in track gauge. Seems to work ok.

Stephen

Don't want to be too pedantic, if you work in OO the actual difference in gauge works out at 13½" which accentuates the narrow gauge look of some models when viewed head on.

Our models behave differently and need a larger kinematic envelope (allowance for sway/cant) than the prototype, the majority of locos and as they are largely unsprung and run round far tighter curves.  

In addition some models are substantially wider than scale, the Jouef Class 40 British Rails longest diesel scaled out 18" wider than the prototype 

 In practice its really a matter of setting structural clearances  to suit your highest, widest-longest locos and coaches rather than trying to scale down the prototype.

In the UK and Ireland specific requirements existed in relation to minimum platform widths and distance between coaching stock and tunnel walls/bridges(sufficient space to open carriage doors while in tunnels, on or under bridges in an emergency), unless an exemption was granted.