Garden Railway Forum

FWLR wrote: ↑Wed Nov 07, 2018 9:00 am I love your Trestles Greg. Your line is the most impressive I have seen. It makes you think you are actually there, watching the train go through the rocks is amazing…Throughly enjoyable episode.

Just a thought though. Your Trestles are only just needing repair after 10 or 20 plus years.
To scale that would be about 100 to 120 years wouldn’t it….

Scale time? That's an interesting concept Rod.

Infinity and beyond……

philipy wrote: ↑Wed Nov 07, 2018 6:35 am That big trestle is soooo impressive Greg. I can understand why you didn't paint it but I am surprised that you didn't use creosote or similar preservative on it?

I think I did 'dip' the ends in creosote - probably should have soaked them more. Can't use creosote now.

ge_rik wrote: ↑Wed Nov 07, 2018 8:19 am It's amazing that your wooden bridges have lasted so long without preservatives of any kind. I used to think that your part of Oz was fairly arid until you recommended a video to me showing the development of the Sydney sewage system which has to cope with more annual rainfall than London.
Rik

We do get lots of rain sometimes. The runoff from 2 neighbours' yards finishes up running under the trestle...

Thanks for everyone's comments.
Just a couple of more pics to 'finish off' the trestle story.

Here's me beside the trestle 21 years apart. The shirt and my hair seem to have 'selectively' faded in the latest pic.

Kookaburras find it a useful lookout place for finding worms.

Things clearly improve with age, Greg.

Rik

The shirt still fits even after 21 years Greg. And not a lot of fading also, make them to last in Australia….

It's a boomerang shirt Rod, Greg has thrown it away countless times, but it keeps on coming back!

FWLR wrote: ↑Fri Nov 09, 2018 7:29 am The shirt still fits even after 21 years Greg. And not a lot of fading also, make them to last in Australia….

The shirt has been relegated to painting duty only.
The tag is so faded I can't read where it was made. Possibly is was made in Oz 20 yrs ago, but these days nothing is made here. We just dig up iron ore, coal and gas, ship it out and continue to live in a fools paradise. Ooops, way off topic.

Peter Butler wrote: ↑Fri Nov 09, 2018 11:44 am It's a boomerang shirt Rod, Greg has thrown it away countless times, but it keeps on coming back!

Very good Peter.

Episode 3

Now we get to the bridge that I am most proud of: It’s a ‘stone’ viaduct, with 11 arches, carved from Hebel lightweight concrete. Hebel comes in 24” x 8” x 8” blocks (Oops, I’ve slipped into Imperial). So obviously, each arch piece could be no more than 24”. I was able to use 1.75m radius for the track. But because I needed a width of 180mm for the track plus vehicle overhang, I could only make each arch segment 450mm long. The 150mm cut off the end was used for the piers. As shown below, I had to cut a small triangular piece off each end and then cut the 1.5m radius curve in the inside and outside of the curve.
Then I didn’t have enough ‘depth’ in the 200mm high block to use a circular arch, so I used an elliptical one. And the ‘radius’ of the ellipse is different for the front and back of the arch, and also from the arches on the straight portions. Suitable templates made it easier. Having marked out the arches, I used a long 1/4” masonary drill to drill many holes around the markings from back and front at the correct angle! and then gently use a saw to cut right through. Then an angle grinder and rasp, to smooth the arch out. My backyard was covered in white dust when I had finished. Make sure you wear a mask! Then it was just BORING scribbing the stone.
I used ‘proper’ (expensive) Hebel cement to glue the arches and piers together and used the semi-circular hunks from the removed arch as buried foundations. Waste not, want not. The parapets are cut separately and hebel-glued on. Having finished all that, I found I had created a perfect Roman Aqueduct - it held water nicely. So I had to drill oblique holes from the track bed out the side to let the water out.
The Hebel is coloured using various cement oxides mixed in water and brushed on.
I then put down some ballast in the ‘channel’ and laid the track. The parapet is low enough that most vehicles with large overhang are higher than it anyhow.

After a few years, every arch had cracked. There is only about 3cm thickness from the top of the arch, but interestingly, the cracks never appeared at the thinnest, top of the arch – always a bit away. Like this:
It hasn’t affected the strength at all (it’s still standing!). I can only assume I should have used more solid foundations. Anyhow, to add some detail to the scene, I added some work scaffold at this worst cracking. The scaffolding is bamboo skewers and heat-shrink tubing.

One last picture, (because I’m proud of it, and it’s coming up to its 20th birthday.)

Just as an aside here. This pic shows how I surveyed my yard for constructing the GR. I put pegs in the ground at 2m grid and measured their heights from a datum using just a spirit level, a 2m length of wood and lots of pieces of wood of different thickness. The highest point of my track, which is inside my train room, is the datum ,so all heights show as negative. The pic shows less than a quarter of my yard.

I would be very proud of that Viaduct Greg. And so you should be too.

It’s brilliant and nearly 20 years old now too, wow. They way you have worked out your angles and applied them to the arch and the columns is brilliant.

The scaffolding is truly inspired, never thought of putting heat-shrink on skewers…

A truly superb Viaduct and worthy of the highest praise……

Thanks Greg, absolutely wonderful. I do love the way the water has marked the face as it drains down from the weep holes.
I can sympathise regarding your dust, even my single arch bridge has generated dust that simply won't go away no matter how much I dampen, brush and sweep!

That's a truly inspiring viaduct Greg, and I can't help but admire your patience in constructing it so diligently. Excellent modelling

Love the scaffolding!

Greg, Just thinking, shouldn't you have some speed restriction notices around that crack & hump?

The viaduct is a superb piece of engineering and you have every reason to be proud of it, congratulations. As others have said, the scaffold is also inspiring and I am about to continue to build my ruined castle which I started years ago and then became sidetracked. The scaffold will enable me to show collapsed walls undergoing some consolidation. I can have site offices for the builders, and supplies of materials on site to complete the picture. You have inspired me, although it will be several months until the weather improves enough for anything to take shape..... thanks Greg!

Another great installment, Greg. Your viaduct is truly impressive. I especially like the way you have capitalised on cracks in the structure with the scaffolding. Nice touch.

Rik

I can only agree with all the comments made. Superb stuff Greg. Absolutely superb.

MANY thanks to everyone for their nice comments. I really appreciate them.

philipy wrote: ↑Thu Nov 15, 2018 9:31 am Greg, Just thinking, shouldn't you have some speed restriction notices around that crack & hump?

Absolutely there should be speed restrictions! I'll see to it!
I have had ideas for a long time now that the site should have a track work gang with an animated figure who moves off the track and waves a flag, detonator sounds as a train approaches etc. But that will need infrared train detectors etc.

Anyone else have ideas to take up my time?

gregh wrote: ↑Fri Nov 16, 2018 12:17 am MANY thanks to everyone for their nice comments. I really appreciate them.


I have had ideas for a long time now that the site should have a track work gang with an animated figure who moves off the track and waves a flag, detonator sounds as a train approaches etc. But that will need infrared train detectors etc.

Anyone else have ideas to take up my time?

Not just at the moment Greg…..Let me think… s…