Advice on clearance between decks

[mrhd]

I am looking to build a two level layout with an incline to move between levels and I was looking for advice on clearances between levels.

I have been measuring my rolling stock (MM locos and IRM wagons) and they all seem to come in around 60mm give or take in height. I also have a plastic kit retaining wall in the parts box which is about 70mm tall. So I was thinking if I allowed about 80mm  (plus 10mm for the plywood) clearance for the upper road-bed would that be enough.

I have about 3.5m of a run to climb the 90mm giving about 2.5%, by moving up to 100mm it would be creeping up towards 3%. The rakes will be short - max 5 coaches or 6 wagons typically - and they are all modern locos which should cope with 3%. But if it is too tall then I would have to build-up the ground under any kit bridges or tunnel portals so no point in going too high.

Has anybody on here used tunnel portals or bridge kits, if so what seems to be the standard heights for loading-guage underneath and/or the height of the bridge deck.

[murrayec]

Not knowing the plan of your layout! but you should consider access height between the levels? should something de-rail on the lower deck one needs to be able to get in at it! maybe you have a plan for this......

Eoin

[DJ Dangerous]

Chatting with @murphaph about this very thing recently.

Maximum grade is supposed to be around 1 in 50, ie a 10cm increase over 5m.

Two things that Murph pointed out were that the MM locos don't have traction tyres, so it won't take much of a gradient to slow or stop them, and that pushing trains up is even worse if they have standard tension-lock couplers, which ride up on top of one another.

Maybe post a rough plan of what you want with a few measurements, and somebody will have an idea.

Dave, the builder of the new Fry Model Railway is on here, but I forget his username. I'm sure somebody will remember.

 

[murphaph]

Chadwick model railway YouTube channel released a video recently about managing inclines. Might be worth a look.

Also remember that an incline on a curve appears steeper to the loco than one on a straight.

[Billycan]

If you are planning to have points on the upper deck you will need to make allowance for any point motors that you need underneath - min 80mm for DCC Concepts motors.  Higher might be necessary if boards are permanent. 

[Broithe]

We had a large layout with a straight incline, as an excuse to use a suspension bridge. It rose four inches in eight feet, but had bends not far from the bottom ends.

The bends, as @murphaphsays above, do add to the resistance. It would be noticeable, with longer trains, that the ascent would accelerate slightly (it was a DC layout) once the whole train was on the straight.

We didn't have huge issues with the gradient and there was a great variety of motive units on there - new and old, traction tyres and all metal wheels, etc.

 

A few points did emerge:-

Heavier locos were, as would be expected, less prone to slip.

Murphy products (only 141/181 on there whilst it existed) were amongst the best performers.

Before you commit to a final design, it might be worth building a test set-up with the intended track profile?

 

 

[DJ Dangerous]

Outstanding, @Broithe!!!

Any more photos of it?

So your grade was 1 in 24?

That gives me hope for some of my dreams were dashed by the 1 in 50 rule.

[PJR]

I also would love to see more photos please

[Broithe]

1 hour ago, DJ Dangerous said:

Outstanding, @Broithe!!!

Any more photos of it?

So your grade was 1 in 24?

That gives me hope for some of my dreams were dashed by the 1 in 50 rule.

1 hour ago, PJR said:

I also would love to see more photos please

 

I'll stick some up elsewhere, to avoid derailing this (hah!).

There's a few videos, too.

The ramp was based on some hardboard we had left - hence the 8 foot length dimension. The lift might have been 3½  inches, but it was 'steep' in the generally accepted view of model layouts.

If anybody has a Hornby suspension bridge to hand, that defined the lift - mine is 200 miles away and it probably wouldn't accepted as an essential journey.

It was clearly close to the limit, but we rarely had issues. Restarting on the slope was not always possible without the Hand of God.

We never had any motor stalling issues, all the propulsion failures were slippages.

The number of axles in the train was as important as the weight of the carriages & wagons.

Most trains were drawn, we didn't do a lot of propelling, but I don't recall any special difficulties there, though.

We had the obvious advantage that it was fairly accessible - if it had been more awkward, I might have been inclined (hah, again) to drop the bridge a bit, as there was nothing underneath it that mattered.

 

Edited February 9, 2021 by Broithe

[Ironroad]

Difficult to advise without knowing the plan.  If all that's needed is a flyover, then you can split the gradient between both lines, with one descending and the other rising. This reduces the distance required to get the required clearance and allows for easier grades. However, this is not possible with a flat solid top baseboard You should consider an open frame with the track bed supported on stilts from the framing (in places it may sit directly on the framing) and I would suggest 12mm plywood for the track bed.  An open frame has the advantage of being lighter and lot of options for landscaping.

[mrhd]

Thanks for all the comments and advice.

So far all I have is the plain baseboard,  it is  ring of eight 600mm x 1200mm boards. 

I am thinking I will put a back-scene support around 3 sides and the main scenic area would have most of the track at base-board level with an elevated "branchline" at the rear of the scene which would run in a loop and have an access ramp at the very back. I plan to have scenic breaks at the left and right of the front portion, at least one of those would be a rail over-bridge I am thinking, and I have to use that retaining wall kit somewhere  

I am not big into shunting hence the desire for multiple roundy-roundy levels to allow me run multiple trains simultaneously. I would like to have landscape on the sides and some at the back maybe. I would prefer to keep point work on the upper level to a minimum so that I dont have to worry about failing point motors in inaccessible places. The more complex track work would be on the lower level with point motors easily accessible from under the baseboards. The clearances are really only critical where there lower level main-line crosses under the upper level line at either end of the front scenic section.

I have been following Charlie Bishop's Helix build on Chadwick and he had to reduce the gradient on the helix alright and used the 'powerbase', hopefully i can get away with more as my trains are shorter than his.

@Broithe mentions 4in/8ft (~4%) without too many problems, that sounds encouraging and I have the space for that. Once I get the backscene boards on I can do some trials when there is less chance of a loco taking a dive over the edge. 

[DJ Dangerous]

Looks great!

I had a very similar baseboard arrangement in the attic many many years ago; eight 2' x 4' baseboards arranged just like that to give a 14' x 6' layout.

Looking at what you have there, you could almost triple the length of your ramp by following the curve of the upper level, then running it alongside the front of the upper level again, reducing the gradient to a third of what it is.

If the upper level is at 10cm high, then your ramp would have dropped to only maybe 3cm high by the time it had gotten around to the front, so wouldn't obscure anything, really.

 

[mrhd]

Thanks @DJ Dangerous your comment about a longer run-up got me thinking and I realised I only need the full clearance where the upper and lower levels cross at the front. So I can drop the upper level to ~6cm along the back and have a shallower up-ramp, and I can make up the remaining 3-4cm of clearance by sloping the upper level upwards as it comes from the back to the front cross-over point. I reckon I can achieve a maximum of 2% this way which should be fine for MM locos.

[DJ Dangerous]

Sounds excellent! Hope that we'll see some of the build here on the forum!

[Noel]

On 8/2/2021 at 7:26 PM, mrhd said:

I am looking to build a two level layout with an incline to move between levels and I was looking for advice on clearances between levels.

I have been measuring my rolling stock (MM locos and IRM wagons) and they all seem to come in around 60mm give or take in height. I also have a plastic kit retaining wall in the parts box which is about 70mm tall. So I was thinking if I allowed about 80mm  (plus 10mm for the plywood) clearance for the upper road-bed would that be enough.

I have about 3.5m of a run to climb the 90mm giving about 2.5%, by moving up to 100mm it would be creeping up towards 3%. The rakes will be short - max 5 coaches or 6 wagons typically - and they are all modern locos which should cope with 3%. But if it is too tall then I would have to build-up the ground under any kit bridges or tunnel portals so no point in going too high.

Has anybody on here used tunnel portals or bridge kits, if so what seems to be the standard heights for loading-guage underneath and/or the height of the bridge deck.

On Kingsbridge I designed a 3" difference in height between upper level and lower levels. That gives 70mm clearance under the upper baseboard which is 9mm ply. Everything fits except two steam tank locos with particularly tall chimneys. Bare in mind the height of your choosen track bed. We have a 3% transition incline from lower level to upper level which is rarely used, typical coach rakes are 4 to 6 and no problems. The only problem I had was with 42ft container flats which required a pair of 071s to get them up the incline. Max no of wagons the pair of 071s could get up the hill was six 42fts. No problems with other wagons (ferts, tara, cement, etc), all free flowing axles. Its your layout so go with what ever separation level you like. Personally I prefer minimal height differences but sufficient for off the shelf support wall kits (ie arches, etc), bridges, etc.