Check Rails on Curves

[Right Away]

Looking through an article recently of the ex LSWR route, my attention was drawn to photographs of Poole, Dorset and the curvature through the station. 

 

I mused at the concept of providing a check rail in 4mm scale but shuddered at the thought of the complexity of flange widths, clearances etc and came to the conclusion that this is clearly one for the Finescale modeller. To include check rails wth any degree of realism would essentially mean starting from scratch and would be very difficult to add to an existing line, and that's before the conversion of all wheels. I wouldn't think that  model trackwork manufactures would consider track with a "double rail" one side as commercially viable, and therefore must ask the question - is a check rail a detail too far?

 

Given that for reasons of space (or lack of) many of us have to compromise on reality when it comes to rail curvature, the inclusion of a check rail, if at all possible, would only be practically viable on more  generous curves.

 

Aside from all this, on the prototypical front, would any member know the minimum radius of a curve on a main running line when a continuous check rail becomes necessary? I would assume many variables come into play; location, line speed, cant, gradient and therefore a generalised answer may not be possible. 

 

[Jeff Smith]

Depending upon what standards you are using, the check rail gaps could be the same as whatever already exists in your points.  There would not be any wheel adjustment necessary.  However in OO I think it would accentuate the narrow gauge, especially if using code 100 rail.

[Gibbo675]

29 minutes ago, Right Away said:

Looking through an article recently of the ex LSWR route, my attention was drawn to photographs of Poole, Dorset and the curvature through the station. 

 

I mused at the concept of providing a check rail in 4mm scale but shuddered at the thought of the complexity of flange widths, clearances etc and came to the conclusion that this is clearly one for the Finescale modeller. To include check rails wth any degree of realism would essentially mean starting from scratch and would be very difficult to add to an existing line, and that's before the conversion of all wheels. I wouldn't think that  model trackwork manufactures would consider track with a "double rail" one side as commercially viable, and therefore must ask the question - is a check rail a detail too far?

 

Given that for reasons of space (or lack of) many of us have to compromise on reality when it comes to rail curvature, the inclusion of a check rail, if at all possible, would only be practically viable on more  generous curves.

 

Aside from all this, on the prototypical front, would any member know the minimum radius of a curve on a main running line when a continuous check rail becomes necessary? I would assume many variables come into play; location, line speed, cant, gradient and therefore a generalised answer may not be possible. 

 

Hi RA.

 

I know from locomotive diagram books that the minimum curve for most steam locomotives is around 6 chains, some are noted as down to 4.5 chains with gauge widening although suspect 6 chain curves are not usually found on main lines.

 

For reference a chain scales at 10.39" or 264mm in 4mm scale so a 6 chain curve should be have a radius of 62.36" or 1584mm.

 

The curve at the centre of this map running on the south side of the triangle junction is between Meols Cop and saint Luke's in Southport and is a check railed curve with a 15 mph speed limit. You could perhaps scale the curve from the map or find a similarly check railed curve that you know of:

 

https://maps.nls.uk/geo/explore/side-by-side/#zoom=15&lat=53.6479&lon=-2.9799&layers=168&right=BingHyb

 

Railways are very straight, more so that modeling allows !!!

 

Gibbo.

Edited February 16, 2019 by Gibbo675
Missed a "_ _ _ _ _" out of sentence.

[Gary White]

Poole Curve/Northam Curve 

 

The curve on approach to Poole station on the down line is limited to a max line speed of 20 mph it is a very tight curve due to the level crossing and also the location of the station also the curve on the down line approaching Northam at Southampton is 25mph this is also fitted with a double check rail though the curve .

 

Hope this helps

[TheSignalEngineer]

Continuous check rails are usually provided when the radius on a running line gets down to 10 chains or less.

 

In other instances double check rails are sometim.es provided approaching and across viaducts or similar situations where a derailment will inevitably have catastrophic results

Edited February 16, 2019 by TheSignalEngineer
Second para added

[34theletterbetweenB&D]

7 hours ago, Right Away said:

...I mused at the concept of providing a check rail in 4mm scale but shuddered at the thought of the complexity of flange widths, clearances etc and came to the conclusion that this is clearly one for the Finescale modeller. To include check rails wth any degree of realism would essentially mean starting from scratch and would be very difficult to add to an existing line, and that's before the conversion of all wheels. I wouldn't think that  model trackwork manufactures would consider track with a "double rail" one side as commercially viable, and therefore must ask the question - is a check rail a detail too far?...

The only scales in which a continuous check rail on a curve will look well is in my opinion the 'true scales' such as P4 and S7. That's because both railhead and flange gap need to be true scale to look well.

 

Now here's my observation of P4 layouts, in answer to your question: "is a check rail a detail too far?".

 

I think it must be. Passenger carrying lines with curves below 8 feet radius are exhibited, check rails are not. (I haven't been to Scaleforum as it consistently falls on dates conflicting with significant family events, three line whip etc..) Now I well remember this question was posed in a meeting of an MRC group building a P4 exhibition layout, back in the dawn of time when this was the red hot thing to do in 4mm; the consensus (OK, those who shouted loudest) was that we had to build a working layout and there were quite sufficient problems to solve to get to a running result, so will you please shut up with that idea.

[Jeff Smith]

Interesting.  If modelling a prototype location surely all the prominent track details should be included.  A check rail wouldn't be any more difficult to fit than 3rd or 4th conducting rails.  Would a Southern modeller leave the 3rd rail off?

[Merfyn Jones]

Interesting comments  there.

My opinion is if modelling a real location use check rails where they were found

Code 100 does look a bit silly in OO.  Recently we relaid our OO layout at the club with new Peco bullhead and as the prototype had check rails at both ends of the layout (3' radius aprox.) we fitted them. A labour of love and wouldn't want to do it too often. C&L chairs used and it doesn't look bad at all.

[phil-b259]

49 minutes ago, Jeff Smith said:

Interesting.  If modelling a prototype location surely all the prominent track details should be included.  A check rail wouldn't be any more difficult to fit than 3rd or 4th conducting rails.  Would a Southern modeller leave the 3rd rail off?

 

I would suggest that the absence of check rails has a lot to do with the need for compression in the hobby while not restricting trains to a crawl.

 

Its the same reason why more than a few lines with OLE omit the actual wires - the inclusion of masts suggests it’s there but avoids the fact that accurate wiring would be increadbly fragile if done to the correct scale - not to mention impossible to tension like the real thing.

 

Similarly while 3rd rail gives the correct impression - how many models actually have their shoegear at the correct height / distance from the bogie to ensure they accurately glide along the top of it?

 

If you examine the real railway, check rails are not used unless the curve gets really tight - which means we are talking about less than 20mph linespeeds, most modellers wish to run / represent lines with at higher speeds in spite of the compression forced by small homes, etc and no check rail is therefore appropriate.

[jim.snowdon]

7 hours ago, TheSignalEngineer said:

Continuous check rails are usually provided when the radius on a running line gets down to 10 chains or less.

 

In other instances double check rails are sometim.es provided approaching and across viaducts or similar situations where a derailment will inevitably have catastrophic results

Quite right as far as curves are concerned, where the object is to prevent derailments by keeping the flange of the leading outer wheels off the rail and thus flange-climbing. It doesn't, though, apply to tramways, where curves of far smaller radius than 10ch (or 200m in modern standards) can be found, laid in flatbottom rail, without check rails.

 

 The "double check rails associated with bridges, etc., are not check rails but guard rails. These have a greater flangeway,  the object being to maintain guidance of the derailed vehicle in the event that it has derailed. The flangeways for check rails are larger than for check rails, as they should not normally  be in contact with the wheels.

 

Jim

 

[Sprintex]

I've modelled a check rail on my N gauge layout, although at this scale it's easier as you can get away with using painted styrene strip instead of metal rail

 

Paul 

 

[Merfyn Jones]

Different requirements between a passenger line and others is shown here.  

Check rail on the platform line but not on the loop, at Blaenau Ffestiniog.  Note how the curve is not very small.                                                                                           

Check

[Guy Rixon]

Adding a check rail to a model would probably add a lot of friction and could limit train lengths. I'm planning a P4 layout threaded through a city and was going to check-rail one of the running lines where the most-plausible route took the curve down to about 9.8 chains. Then I realised that the curve was also on a 1 in 47 gradient (also required by the setting) and thought that a check rail would be a bit too much for my tiny locos. So I "re-surveyed" and opened the curve out just above 10 chains. 

[Jeff Smith]

I think you would possibly have to open up the check rail gaps a bit in P4.  Especially if using 6 coupled locos or 6 wheel carriages; and have enough centre axle sideplay.

[Guy Rixon]

19 minutes ago, Jeff Smith said:

I think you would possibly have to open up the check rail gaps a bit in P4.  Especially if using 6 coupled locos or 6 wheel carriages; and have enough centre axle sideplay.

It depends on exactly how tight is the curve.  If it's a larger radius, scaled, than the full-size vehicle could tolerate, then a check-rail set to P4 flangeway should be OK (IIUC & IMHO - haven't built one to try). Tighter than that, yes, I think a wider flangeway might be needed.

 

Further, six-wheeled coaches always need lots of play in the middle axle (or Cleminson arrangements) to get round tight curves, whether or not a check rail is present. This is true in any scale and with any standards, but the "coarser" standards help a bit by allowing more play between wheel and rail.

[Red Fox]

On 16/02/2019 at 08:53, Right Away said:

Looking through an article recently of the ex LSWR route, my attention was drawn to photographs of Poole, Dorset and the curvature through the station.

 

I'm slowly building a layout based on Poole in OO and added check rails as I felt it was a distinguishing feature.  I've not powered it up yet but the track has passed the push test for bogied stock, can't remember if I've tried any Co-Co locos yet but I've had no issues so far.  I used C&L Finescale gauges with 1mm flange gap and C&L and Exactoscale Chairs.

 

Edited February 18, 2019 by Red Fox

[Michael Edge]

The EM gauge Carlisle layout has a checkrailed reverse curve on the M&C line, minimum radius on it is 53.6". The checkrails are at normal flangeway distance (1mm) and cause no problems whatsoever. This track is ply and rivet construction though, it's not very easy to add checkrails to plastic based track.

[Killybegs]

The prototype had lots of check rails in the Forest of Dean so I had no qualms about using them on Clinkerford. I seem to recall that the flangeway was set at 1mm and gave no running problems.

[RailWest]

Nice checks rails indeed - but if you're going for authenticity, where is the trap-point at the exit from the loop/yard please ? :-)

[Killybegs]

Guilty as charged. Ignorance at the time the track was laid and lassitude when I knew better.

[kevinlms]

On 17/02/2019 at 03:22, 34theletterbetweenB&D said:

the consensus (OK, those who shouted loudest) was that we had to build a working layout and there were quite sufficient problems to solve to get to a running result, so will you please shut up with that idea.

Perhaps the reality was that if a 'roundy', due to the space most people/clubs have available, check rails on the 180 degrees on two tracks at each end, would have been overkill.

 

A bit different, if you have a small straightish station, with 1 or 2 fiddle yards, where a short section of check rail, could look special.

[Merfyn Jones]

A few shots showing the effect on Peco bullhead OO. Aprox. 3' radius on our club layout.

 

 

 

[keefer]

Burntisland in Fife on the ECML used to be checkrailed on both lines, with a PSR of, i think, 40mph.

https://www.geograph.org.uk/photo/1950667

 

More recent pics seem to show a checkrail on the Up (southbound) line only

https://www.geograph.org.uk/photo/3606902 (ignore the rails in the 4ft)

I'd have thought the tighter radius Down line would be more likely to need a checkrail?

[jim.snowdon]

Since inside keying on bullhead track went out of fashion a great many decades before the second picture was taken, both roads in the second picture are check railed. Check rails are the only occasion where there are keys visible in the four-foot.

 

Jim

[keefer]

Ah right, thanks Jim - i see it now