Minimum radius curves in NSW

 
  NotebookMan Assistant Commissioner

Location: Wahroonga NSW
On the gradient and curve diagrams available to me (ARTC website and ancient NSWGR book from ARHS), I see radii of 8 chains (160m) on the Islington Jn - Scholey St curves and 10 chains (200m) on the Waratah - Scholey St curves. These curves are evidently acceptable to traffic headed for Port Waratah, including recent heritage steam trains.

Questions:

Is 8 chains the minimum curve radius acceptable for operation of container and coal trains? I suspect that some balloon loops would be tighter than others. I know they have different speed limits, but other factors affect that.
What are the minimum curve radii acceptable for operation of XPT, Xplorer, Hunter and Endeavour rolling stock? No, I'm not planning to operate a tour.

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  Draffa Chief Commissioner

Damn good question.  Here in QLD, QR specifies a minimum radius of something like 800m for all new builds.  Old, pick-n-shovel era track can get down to 100m (and I think 80m somewhere on the Kingaroy line).
  NSWRcars Assistant Commissioner

On the gradient and curve diagrams available to me (ARTC website and ancient NSWGR book from ARHS), I see radii of 8 chains (160m) on the Islington Jn - Scholey St curves and 10 chains (200m) on the Waratah - Scholey St curves. These curves are evidently acceptable to traffic headed for Port Waratah, including recent heritage steam trains.

Questions:

Is 8 chains the minimum curve radius acceptable for operation of container and coal trains? I suspect that some balloon loops would be tighter than others. I know they have different speed limits, but other factors affect that.
What are the minimum curve radii acceptable for operation of XPT, Xplorer, Hunter and Endeavour rolling stock? No, I'm not planning to operate a tour.
NotebookMan
There are main line 8 chain (160m) radius curves at Zig Zag bottom road, used by nearly everything on the NSW system.

I don’t know about current standards, but I believe that in the past all rollingstock in NSW could operate on 5 chain radius curves. Although not used on main lines, some pointwork and sidings may come close to this radius.
  NotebookMan Assistant Commissioner

Location: Wahroonga NSW
Thanks, guys. NSWRcars, you've started me thinking (always a helpful development). I recall an ARHS tour to Oberon in the early 70s, where a change from steam to branch diesel and from mainline carriages to long screw coupling stock was required for reasons other than engine requirements. A quick look at the book shows frequent 5 chain curves as the minimum on that branch. Ditto Kunama, the Batlow remnant of which I visited on an RTM tour some years later. I can't remember that train now, I think it was tin hare vintage.

This suggests to me that locomotives (particularly 20th century branch line variety) might be more adaptable than modern passenger stock. 1 in 25 grades and the length of the 5 chain curves might come into it too.
  awsgc24 Minister for Railways

Location: Sydney
This suggests to me that locomotives (particularly 20th century branch line variety) might be more adaptable than modern passenger stock. 1 in 25 grades and the length of the 5 chain curves might come into it too.
NotebookMan
There are 5 chain curves, and steep grades on:
* Oberon
* Dorrigo
* Batlow lines.
* IIRC at least one 4.5 chain curve.

I seem to remember that QR had some 3 chain curves on one of the inland mainlands, from perhaps Rockhampton or Townsville.

The Oberon, Dorrigo, and Batlow were limited to 19 class locos in steam days, perhaps because of axleload considerations as well as wheelbase issues.

The Canberra line has one set of reverse curves with no intervening straight, and it was forbidden to couple two of the big (Speedo?) oil tankers together. Short reverse curves are also a problem with IIRC 1:8.25 turnouts on 3.66m centred double track. The newish crossover a P9 and P10 at Redfern are about 1:12 turnouts, which create a longer effective straight in the middle of the reverse curve.

Some of the earlier lines were built without transition curves between the straight and the pure curve. Transitions are difficult to add later, particularly if there are tunnels and bridges in the vicinity.

These days, the general minimum radius curve would be 10 chains (200m) on such things as triangles and balloon loops. Think of North Strathfield Triangle, or Islington Triangle(s). The Canberra line now has many 20m transition curves. but these days TC are say 60m, and even longer if line speeds are higher. Superelevation (cant) also has to be transitioned (ramped).

The original Blue Mountains line was apparently a series of 8 chain curves, most eliminated during duplication, except for the un-easable one at Zig Zag.

The Curve and Gradient books are somewhat incomplete:
* Separate curves on either side of island platforms are not always shown (say Belmore or Turramurra).
* Multiple tracks, such as the Relief lines through Broadmeadow are not always shown.
* Speed boards, depending on radius, transition curves or ramps, are not always shown.
* Only a perway surveyor has the detailed information to calculate what the line speed should be. (Ask perwaynut. Smile )
  KRviator Moderator

Location: Up the front
I'm not sure of the radius, but 105 Points at Epping has a restriction about not permitting locomotives across it because it is too tight.
  awsgc24 Minister for Railways

Location: Sydney
I'm not sure of the radius, but 105 Points at Epping has a restriction about not permitting locomotives across it because it is too tight.
KRviator

I assume that you mean the crossover that takes you from P3 at Epping to the Up North Main, which confusingly is mostly used by Suburban trains (and vice versa).

AIUI, this crossover, which is in the middle of reverse curves, has awkward transitions, ramps, etc., and is off limits, not so much to engines, but to whole freight trains. But you cannot tell by looking. Only a perway surveyor can tell.

Unhelpfully, the signalling track plan draws the tracks straight, and the existence of inconvenient curves is an after thought. This crossover should have been put on straight track closer to Sydney.
  NSWRcars Assistant Commissioner

There are 5 chain curves, and steep grades on:
* Oberon
* Dorrigo
* Batlow lines.
* IIRC at least one 4.5 chain curve.

The Oberon, Dorrigo, and Batlow were limited to 19 class locos in steam days, perhaps because of axleload considerations as well as wheelbase issues.
awsgc24
There were no 5 chain curves on the Dorrigo line, sharpest is 7 3/4 chains, I think. It was built to a higher standard than Oberon or Batlow, and although normally operated by 19 class, larger locomotives such as 50 class were permitted.

Some triangles and junctions in the Sydney area have 9 chain radius curves.

Main problem with the longest carriages on sharp curves was potential buffer lock, not an issue with modern stock.
  gordon_s1942 Chief Commissioner

Location: Central Tablelands of NSW
In the Working Time table for each area was a list of where certain carriages such as the Governor Generals was prohibited from traveling along with any wagons I think 70 feet long.
Remember back until the late 60's, 4 wheelers were the norm along with Hook couplings and buffers and most trains were a max of 60 long plus the B/van.
Twice on the Oberon line, an FS Carriage that replaced the HCX brakevan/dogbox passenger vehicle that was away on repair, buffer locked on the UP journey one week.
Now why it did this on the return journey and not going to Oberon I have no idea.
A problem with long vehicles on tight curves was the risk of being pulled off the track, another is the tighter the curve, the greater the friction there is on the wheel flange which needs more power to move it and the risk of the flange mounting the rail and derailing.
During major trackworks, I have seen Bogies 'walk' over track so out of plumb and not have any problems but derail where there didnt appear to be any problem to cause it.
  RTT_Rules Oliver Bullied, CME

Location: Dubai UAE

Twice on the Oberon line, an FS Carriage that replaced the HCX brakevan/dogbox passenger vehicle that was away on repair, buffer locked on the UP journey one week.
Now why it did this on the return journey and not going to Oberon I have no idea.
gordon_s1942

I'm going to take a punt and say going down hill it was riding the buffers, but going up hill the train was stretched.
  gordon_s1942 Chief Commissioner

Location: Central Tablelands of NSW
All trains in those days when leaving Oberon stopped at the Landmark some 3 kms out and the handbrakes on all vehicles were wound up FIRM so to aid the braking on the downhill run to Tarana and as far as I can remember, they were left that way until the Train arrived in Tarana.
The line was fairly straight even down the steep part and it wasnt until near Tarana it was like a snake with a broken back so maybe as it went into the beginning of the curves and possibly on a descent, the buffers overlapped as you suggest.
The curves were so tight you could hear the flanges squealing from a few hundred yards away on the Down Journey at least.
I was Flagging Tarana's upper quadrant Down Starter during Single Line one time just opposite where the branch turns south to go to Oberon and there was no ignoring the squeal made by the flanges.
  mikado5910 Chief Train Controller

Location: Kurri Kurri NSW
Thanks, guys. NSWRcars, you've started me thinking (always a helpful development). I recall an ARHS tour to Oberon in the early 70s, where a change from steam to branch diesel and from mainline carriages to long screw coupling stock was required for reasons other than engine requirements. A quick look at the book shows frequent 5 chain curves as the minimum on that branch. Ditto Kunama, the Batlow remnant of which I visited on an RTM tour some years later. I can't remember that train now, I think it was tin hare vintage.

This suggests to me that locomotives (particularly 20th century branch line variety) might be more adaptable than modern passenger stock. 1 in 25 grades and the length of the 5 chain curves might come into it too.
NotebookMan
If it's the tour I was on, the required branch-line diesel had failed and was replaced by a 45 class. The weather was foul, pouring rain, and the loco struggled up the hill on those tight curves, often losing traction. At one point, the sudden take-up of slack in the couplings resulted in a link snapping under the strain and the train parted, resulting in some very tricky but skilful work on the part of the crew to recouple with an emergency link coupler and get us underway once more.

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