Curved gradiant, building tips, pointers.

[Nodrog1826]

Needs some advice in connection with the above.

Looking to build an underpass, in essence a long meandering loop (There will be some straights.) that will pass under another track.

I know gradients on curves can cause problems for the loco, just wondering how others have tackled the problem.

 

[dunnyrail]

Needs some advice in connection with the above.

Looking to build an underpass, in essence a long meandering loop (There will be some straights.) that will pass under another track.

I know gradients on curves can cause problems for the loco, just wondering how others have tackled the problem.

I used Cut Planks with Angled Joints and supported at the sides with Metal Strip. Inthink that I used the Metal Straps that are used for supplrting wood in House Building Cut up.

https://www.gscalecentral.net/threads/a-new-railway-is-started.260103/page-5

Post 83 on the above link shows exactly how I achieved this. The Gradient was roughly 1:40 and goes over itself with the 4ft Rad Curves and around 16ft of additional ripun on the Viaduct and straight.

The area has now been turned into a Rockery with Stonework to support the Curves.
JonD

 

[kedwards]

The extension to my railway required a gradient of 1:37. The partially completed work is shown in the photo below from 2011. I decided to keep the gradient at a constant 1:37 all of the way from the start to the highest point - along the straight sections, round the bend and across the bridge. Long trains are fine on the straight sections but do struggle on the curve. The lower track is radius 3 with radius 5 transition curves at each end so the curve on the gradient is a larger radius than this. With the lessons learned from this, if I were starting again I would increase the gradient on the straight sections and ease the gradient on the curve.

 

[gregh]

The extension to my railway required a gradient of 1:37. The partially completed work is shown in the photo below from 2011. I decided to keep the gradient at a constant 1:37 all of the way from the start to the highest point - along the straight sections, round the bend and across the bridge. Long trains are fine on the straight sections but do struggle on the curve. The lower track is radius 3 with radius 5 transition curves at each end so the curve on the gradient is a larger radius than this. With the lessons learned from this, if I were starting again I would increase the gradient on the straight sections and ease the gradient on the curve.

I've done a few measurements of 'curve resistance' on my railway and come up with a rule of thumb...
the curve resistance is ABOUT equivalent to a gradient of 1 divided by the radius in metres.

It is really rough as it depends on whether it is bogie stock and the wheel base of 4-wheelers.

So for example on a 3% grade, a curve of 1.2 m radius 'looks like' a 3 + (1/1.2) = 3.8% grade

Or looking at it another way, if the straight grade is 3%, the 1.2m radius curve should have a grade of 3 - (1/1.2) = 2.2%, to have about the same effect on the train..

 

[Rhinochugger]

Yes, Gordie, agree with both of the above - ease the gradient on the curve, and have a slightly steeper grade (to compensate) on the straights.

It also depends on the radius of the curves - even on the level, R3 (8 ft diameter) affords a fair amount of resistance on a longish train. LGB large flanges will also add to the drag.

Part of the problem is that in our model world, our curves are significantly sharper than in the 1:1 world.

I'm just constructing the grade up to horseshoe curve which is hopefully less than 1:37 - I'll let you know how it goes when I'm done

 

[GNB]

Here's some views of a cross over loops with an 'underpass' on a double gradient, i.e. one drops as the other climbs in order to minimise the individual gradients and maximise the clearance.

The inner lower curve is LGB radius 1, the outer lower curve is radius 2 and the high level curve approximates to LGB radius 3 (flexi-curve, made to fit).

The steepest gradient is 1:20 (5%) on the straight sections with a reduced progressive gradient in the curves of between 2 & 3%.

 

[korm kormsen]

on my indoor layout for short trains (stainz, motored tender plus up to five foot of cars) i have gradients with R1 curves.
while the gradients are 5 to 6 % on straights, by trial and error i found out, to make them about 1% less steep on the curves, for the trains not to slow down.