Tightest Curve on a Standard Gauge Mainline

[What About The Bee]

What is the smallest radius curve on a Standard Gauge Mainline, in the UK?

The Gotham Curve claims to be the smallest, a radius of 55 yards (165 ft). In OO, that would be 660 mm, or somewhere between a 5th and 6th radius curve.

https://en.m.wikipedia.org/wiki/Gotham_Curve

The article carefully excludes industry and harbor shunting lines.

For the LMR, the tightest curve was purported to be at the Liverpool end of the line, just after the Wapping Tunnel.  Bury provides us with two views of the Wapping Tunnel. 

The first is of the inside, looking out. A slight curve to the left

Another view is at the bottom, looking in. A slight curve to the right

I've been able to locate this curve at the mouth of the tunnel on an Ordnance Survey map, Lancanshire CVI (106). Issued in 1851, 6 years after the LMR was consolidated. Find the red dot. 

That is the location of the lithograph view from the bottom, looking in. The green bidirectional arrows show the tunnel (on the left) and the exposed lines (on the right). The building is labeled LNWR Goods Terminus, the LNWR being the successor to the LMR, the Wapping Tunnel the goods line. Note the Wapping Docks in close proximity. The curve in the lithograph is shown at the yellow arrow. 

But look at that curve by the orange arrow. My word! That is very tight, but what is the radius? I puzzled and puzzled. How to get the radius? The distance scale on the map indicates 80 chains to the mile, a quick bit of maths informs us that 1 chain is 66 feet. Okay, so I have a reference.

It finally dawned on me that I could simply superimpose a circle on the image, and measure the radius. The first problem is to determine what the map represents. We can tell from the lithographs that there is double track, but does the map show 1 or 2 tracks? I see what appears to be two lines, with some apparent cross ties, how far apart are the lines? I find that the two lines are drawn ~13 feet apart. So each solid line represents a pair of rails. The map shows double track mainline, a breakthrough in map interpretation. 

I then drew two circles, one for each track. The outer red, the inner blue. I carefully examined the pixels and converted the radius from pixels to feet. For the red outer radius, I obtain 123 feet +/- 5 feet. For the blue inner radius, I obtain 110 feet +/- 5 feet. It is difficult to say exactly what each pixel represents, so there is some uncertainty, reflected in the error band.

Converting to OO, I find the red outer radius is 492 mm, reasonably just under a 3rd radius curve. For the blue inner radius, I find 440 mm, just 2mm over a 2nd radius curve and certainly well within my error band.

Now there can be some quibble. Is that curve on the harbor line, for shunting? Perhaps so. Yet I would also suggest it leads directly onto the mainline. Perhaps qualifying for the "tightest curve on a mainline".

What is your nomination? Should we throw this open to industrial and harbor lines? Sure, why not!

Bee

[Rallymatt]

loosely connected to this, I did read that the BR standard 9f 2-10-0 was designed to cope with dock curves that would be around R4 in TT:120. Quite an achievement that one of the largest steam locos built could get right into industrial areas that we typically associate with small dock shunting locos. Not as tight as the lines you have found but still impressive.

[threelink]

Great bit of research, Bee. If the rails ran uninterrupted through the Goods Terminal building and were connected directly to the line through Wapping tunnel from the LMR main line at Cavendish cutting it would support the notion that the curve is main line.

[What About The Bee]

Hi Three Link

I will begin with the overview. To the left is Edge Hill, to the right is Wapping Docks. Wapping Tunnel, denoted with an orange line, traces the route under Liverpool.

First, I will show Edge Hill environs. Here we see the LNWR / LMR mainline connected to the Edge Hill Station, through the Edge Hill Engine Works and thence to the Moorish Arch. The map itself says "tunnel entrance".

1830s view of this entrance to the tunnel, with the Moorish Arch as the featured architecture.

At the Wapping Dock end of the tunnel, we can see tunnel exit, the curve depicted in the lithographs and the LNWR Goods Terminus.

The entirety of my assertion now hangs on the interconnection under the Goods Terminus building. 

In order to answer the question, I will switch to a larger scale map. Where before, the scale was 6 inches/mile, this new image is at 5 feet/mile, or 10× the resolution.

At this scale, we can see individual rail. That is, we see both rails of 1 track. We can observe individual turntables & etc. I have placed orange lines, showing the obvious interconnection. This image shows more tracks than the previous image, it was updated in the 1860s. Business must have been good. I would argue that that the rail that connects in the 1860s likely connected decade earlier.

And there I leave it. Hornby said my OO LMR models will go around 2nd radius curves. So did the prototype!!

Bee

[What About The Bee]

Rallymatt

Did the 9F have some flangeless driving wheels? 10 flanged wheels & 5 coupled axles on an R4 curve seems ridiculously tight.

With flanges, the locomotive would likely tear the track apart. Our models will just derail. In the real world, the enormous locomotive weight simply pulls the spikes out of cross ties.

Bee

[Rallymatt]

yes Bee, the small driving wheels and flangeless centre pair were to enable this. Not sure how often or how tight these locos ran but certainly you can see the logic, complete trains running into docks with no or reduced shunting, more mechanical loading/unloading reducing waiting times. I suppose with these types of operations the docks were becoming part of the mainline.

Loving the research you have put in, so much to be gleaned from maps particularly referencing older versions where changes can be viewed. UK is very fortunate to have the best mapping going back years with Ordnance Survey. The National mapping resource in UK is held at NLS (National Library of Scotland) I think they have a copy of every OS map ever produced and they will make copies of full or sectional maps in a range of scales too 😁

[threelink]

I am convinced Bee and yes, the 9F did have one set of flangeless drivers although I doubt that it would have coped with this radius of curve!

[Rallymatt]

Correction, spent ages trying to find the source of my info, I was a bit out! Min radius for 9f was 400’ which in TT:120 scales out to 1016mm or radius 14, If it existed!!!! In real life, that’s still impressively tight for such a huge loco and just goes to show what feats of model engineering we expect: exact copy r14, model world r2, no wonder there is sometimes a bit of wheel wobble! 🤣

[atom3624]

So that's ~1355mm radius for OO scale then or ~2.7 metres diameter - should fit in most rooms I reckon!!

Al.

[What About The Bee]

Hello Rallymatt

A person who admits mistake is much more admirable than a person who will argue the error ad infinitum rather than to admit the mistake.

Well done sir!

Bee

[Rallymatt]

Al, remember that 1.35m r is only for a tight industrial scene too! Imagine a full speed main line 😳!!! We are going to need a bigger room!!!

Bee, thank you, it’s the only sensible way 😁

[atom3624]

I suppose not everyone's a Pete Waterman .... !!

Al.

[What About The Bee]

Hi Atom

In 1842, Francis Whishaw published The Railways of Great Britain and Ireland, Practically described and illustrated. Naturally he described the LMR. In that description, he states "The quickest curve is between the River Irwell and Ordsall Lane, being of about a quarter mile of radius." Odd choice of word to a modern ear, quickest. Clearly, Whishaw does not include the 'quickest' curve at Wapping Dock, possibly considering it dock shunting and not part of the mainline.

1 mile = 63,360 inches

¼ mile = 15,840 inches

In OO (76.2) = 207.874 inches

Convert to mm = 5280 mm (R75?)

A perfectly round tail chaser layout will require 11×11 meters. Even Pete Waterman may have an issue!

Bee

[atom3624]

Hi Bee, considering he owns 100's of locomotives; small, medium and large I'm sure Pete could 'take up the challenge', but it can be frustrating at times.

I think this originally is a propagated thread to 'which locomotives can handle 1st radius' ... to which I'll always respond very few, and long term, don't do it unless you really have to, or can afford to!

I'll always go by 'use the largest radius you can' - can be difficult, but makes running a whole lot easier!

Al.

[ModelerXYZ]

According to Wikipedia, the Gotham curve was the sharpest on the Cromford and High Peak railway. It went round 80 degrees at a radius of 50 feet. This gives us a radius of 200mm in 00 scale. This is sharper than a first radius curve, which is 370mm. Only short wheelbase stock were allowed due to the tightness of the curve.

XYZ

[What About The Bee]

Hello ModelerXYZ

I checked and re-checked. Under description, on the Wikipedia page, it says 55 yards, [50 meters] for the Gotham Curve

Now it absolutely is possible that the Wikipedia page is wrong, and the dimension really is 50 feet. I really have no way to confirm the unit, other than by the Wikipedia page.

UK Government website states 2½ chains (55 yards)

https://calmview.derbyshire.gov.uk/calmview/Record.aspx?src=CalmView.Catalog&id=D6367%2F1%2F321&pos=323

Bee

[What About The Bee]

Using the same methodology as I did for the curve at Wapping Tunnel:

The map in this instance is "Derbyshire XXXIII.NW". Find the curve on the map. Gotham Curve is conveniently located at Gotham.

With the curve located, place a circle on the curve, yellow. Then, place horizontal and vertical diameter lines of that circle.

Next, using the scale of the map, place it to read the number of chains. I get close to 2½ chains.

We know the answer should be 2½ chains, from other references. I think the map analysis agrees.

Bee

[atom3624]

... and no reference to Batman ... until now, sorry!

[What About The Bee]

N53°7'23.23" W1°43'15"

Try as I might, I could not find Wayne Manor in the area. Those coordinates place you on a path, crossing the Gotham Curve.

Perhaps you can spot the Bat Cave! 😉

Bee

[atom3624]

face_with_rolling_eyes

[Rallymatt]

Bee, unfortunately using mere co-ordinates won’t help here. You need to use What Three Words ; ‘Holy Tight Radius’

[What About The Bee]

Hi Rallymatt

I gave the latitude and longitude as a way of helping others to find the location.

The street view from there is interesting to me. Firstly, you can see the curve. From a prototypical railway perspective, wow, Holy Tight Radius indeed! Secondly, it gives me the view I'd like to have on my LMR layout. Bucolic fields, stone walls and clumps of trees are what I imagine much of what the railway passengers saw. It is the view down the dirt road.

Another thing of note. The red dot on the map from 1877 is the exact spot the recent images are taken from. Same dirt road. Same Gotham Curve.

Bee

[Rallymatt]

Hi Bee, I was being frivolous 😁 The Batman ref and Gotham made me do it! There is a ‘new’ geo location service called ‘What 3 Words’ idea being the entire planet is split into 3m squares, identified by 3 words, being easier to read and say than Co-ordinates… My infantile brain then thought, what three words would Robin say to Batman (based to 1960’s TV series) to locate Wayne Manor and the very tight railway curve you found… ‘Holly Tight Curve, Batman’

On a more sensible note, access to information has completely changed this hobby, not just photos of locos/rolling stock, but as you have shown, being able to drop in on a map to a location, use Google Street View, reference old maps, identify the types of buildings and even colours in some cases to allow us to create our own interpretations of the tiny worlds we make. It’s one of the most interesting parts of the hobby and has such wide reaching educational benefits. Thanks for sharing 😁

[atom3624]

I still think it's sad that there are probably 2 generations of the great British population, several reading here, who haven't a clue what we're talking about wrt Batman!!

The only Batman they know whispers in a gruff voice!

Al.

[LTSR_NSE]

@atom - how are there just 2 generations?

For every fictional character that has had multiple incarnations in multiple media, there will be a ‘generation’ for each incarnation.

Suggesting that one incarnation is different & all subsequent incarnations are the same seems a little odd.