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Welcome to the Forum, Pete. Your photos are fascinating, and thanks for sharing them. Looks like you have some ambitious plans for your garden railway and have made what looks like pretty rapid progress, so I hope you get to the train-running stage soon.

Mind you, I'm a bit mystified by those intriguing black plastic box-section things you're laying down on top of your concrete foundations. They seem to be capable of being shaped into variable radius curves - how does that work? But more importantly, I'm looking forward to seeing how they will be transformed into a trackbed. Presumably you're not going to build a model of London's District Line using the cut-and-cover approach.

Can you be tempted to contribute a few words to explain what we can look forward to?

Good luck with your efforts, after what looks like very good progress on the first phase.

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Hi All,

Sorry for the lack of words, lurking on the forums for 9 months gave me the impression that you prefer pictures! I've been away for the past 2 weeks, and on mobile access only.

I am using Snap-It, as Chris points out. The plus side is that it should be rock solid for decades to come; I'm avoiding wood at all costs in this. The down side is that it's expensive: that's £500 of snap-it I ordered, and used 3/4 of the parts. This is before purchasing concrete materials, wire and track. I'm budgeting around £1,500 for construction. Consider the value of trains that I'll slowly invest in over the years, and it makes sense to me to invest heavily in the track construction at this stage.

Regarding the gradients of the concrete foundations(for the concrete trunking!) I've used the longest spirit level from B&Q to keep the bubble inside the lines at all times, combined with a laser spirit level to ensure that the long-term gradients stay to 1%, or less. Once I pour the concrete into the moulds, it will self-level to remove any short term variations in gradient. I've also managed to keep the main line to 1.2 Metre radius radius 2 snap-it sections (should give double the radius of the radius 4 set track). I should therefore be ok running live steam (with DC/DCC isolated, of course) at a reasonable pelt. I won't be able to afford live steam for a long while, but it's good to be able to!

The plan is to route wiring through holes in the plastic structure with droppers coming out of the sides. Unfortunately, I want to have computer automation with DCC sensing districts, possibly incorporating RailCom. This means that one rail is connected to a continuous bus, whilst the other rail is broken into sections with a bus of multiple wires used to provide feedback to the system. I also need to wire up multi-conductor feeds to point motors with a single return, as well as wires to sense the position of the point motor position, wires to control the signals and communication wires for Ethernet and Loconet (or other equivalent low speed serial protocol). This is where the conflict for live steam comes in: the forums recommend a 1mm cross section minimum, preferably 2mm for the bus wires. This means each of the parallel sensing wires will need an outer diameter of around 2mm, and I'm concerned that some space needs to be left in the holes for concrete to flow and bond sections together.

Once the concrete is poured, that's my wiring set: I've got to get it right first time. I was considering pull through trunking in concrete, but it wouldn't really work for dropper architecture. So now the snap-it track layout's complete, I'm importing the design into XtrkCAD along with the longest train I intend to run (9 coach East Coast HST) to work out dimensions for platforms and blocking. Initial results point to 12 points and 4 diamond crossings along with either 32, or 48 block detection zones for a double track loop 30 Meters in circumference with a separate station siding too. Once I get a bit further with the CAD this week, I'll upload the plan with some bitmaps and be asking for feedback!

I'll post some pictures of my testbench prototypeing later this week... Thanks for the positive feedback and enthusiasm!

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Hi all,

As promised, some photos, with descriptions below.

224ca01abf3ff8058df1facef3d366d0.jpg

Firstly, I did some testing on pouring concrete into 1 metre long straight sections with 3 pieces of rebar. The first test involved 1 part standard portland cement, 3 parts sand and 3 parts 10mm aggregate. As you can see, I failed to aggitate it sufficiently, and it came out looking pretty bad. The second test involved the same ratio of materials, but substituting the standard portland cement for snowcrete. It gives a much nicer finish, but at £15 odd per bag is 4 times the price. I'll end up dressing up so much of the concrete, it won't be visible anyway. I might reserve snowcrete for just a few sections. You can see how aggitating the concrete gives a much smoother finish. Ignore the grey splatters on this; this came from out of the cement mixer when I was laying the foundations pictured at the start of this topic.

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Here's another shot of the two test sections. I checked encasing the wire in concrete would not increase the resistance of the wire in the first section. The yellow wire is clearly visible on this. Also note how well two oo gauge tracks fit on the run. I've placed these on top to give you an idea of scale. I should be able to fit a narrow platform with 2 tracks on the very outside of the concrete to make one of the stations. I'm ganging a double width section to make 4 tracks with 2 platforms for the larger station.

plastic1.jpg

Here's a side view of the edging. It's a real pain picking away at the plastic in the joins; this system was designed to be laid in a trench. I'll be landscaping most of the walls of this track, so it's not too important. For a couple of the bridge sections, the ridges in the concrete look quite appealing, in my opinion. You can see the lighter layer on the top of the side shot where the aggitated cement has floated to the top. Bottom line is that this rebar concrete is rock solid once poured. I think I may reduce the aggregate content and make the concrete a bit wetter in the final pouring as it's not bonded through the monocoque holes too well, and there will be quite a few wires running through those holes in the final version.

1738ddec96f0875ccd6affa4a478e357.jpg

Here you can see some of my tests with wires. I'm mostly concerned about running 15 Metre multi-conductor wires to points with a common return. Anything more than 3 Ohms in the loop will fail to operate the Peco surface mount motors I've used to test with. I'll have to use different motors in the final layout with switches to the electrofrog points and diamond crossings and switches to feedback the point positions in the real thing. The analog controller works quite happily with 20 Metre long 24 gauge bus wire, so I'm not quite as concerned about that; the layout will use 12 AWG bus wire and possibly 24/0.2 wires for the sensing blocks (I need to see how these pan out in the plan). Each of the tracks will be on a separate bus, and a third dcc bus will be wired to possibly operate points and signals, though I'd rather use direct wiring to my house to keep dcc electronics indoors as much as possible. I'll also fit a power bus which will just run 15 Volts DC for LEDs etc. I'll do a proper electrics post later.

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Finally, I rigged up some electrofrog points to give a realistic load on the motors. You can see some dirty cotton buds I've been testing to clean with iso-propanol to ensure that it doesn't destroy track. I'm playing with some second hand mk2 coaching stock you can see in this picture, just remember to keep the isopropanol off paint! Couplings are a pain. I think a lot of them will have to be upgraded to kadee, but that can wait for a long Scottish winter...

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I am very interested to see this trackbed construction technique being put to the test, after reading about it on here before. Your concrete sections look almost as bomb-proof as mine!

The electronics side of your construction has already gone past my mental capacity for things electrical, but Im really keen on seeing how this impressive looking project pans out. :D

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Just spent today laying the bus cables to the network. I'm taking tomorrow off on holiday to solder droppers, CAT5E network cable, point position sensor cable and to bury the cable conduit under the path and insert it in the back of the shed. I'll also need to wire up the sensor return wires to the other rail of each track. I've ordered 200m of cable for each of the 2 tracks, but fear I might need double the amount following today's experience. Here are some pictures for your amusement...

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http://uk.farnell.com/jsp/search/productdetail.jsp?CMP=i-ddd7-00001003&sku=1204088).

This is the "sense" cable that links individual sections of track back to the shed, and is 2.5 times less cross sectional areal than the bus wires I'm running to the other rail. With the train running at approximately 0.5 Amps, there was a 0.8 Volt drop when this length of cable was introduced to the system. I won't have any sections of sense cable greater than 50 metres. Combined with the bus wire, which forms a parallel loop structure in the network, I'd be surprised if there was more than a 0.5 Volt drop at the far end of the railway. On a 15 Vold DCC system, I believe this should be acceptable.

I also tested switching the points through 100 Metres of 30x0.25mm2 four conductor cable http://uk.farnell.com/jsp/search/productdetail.jsp?CMP=i-ddd7-00001003&sku=1333134

The points were switching readily. My longest run of point motor cable will be 40 Meters; so I'm confident that this will work very well. I'm almost certain that this wire is over specified, but I'd rather it were that way than the other! Should there be trouble with switching the points from the shed, I can still make use of my accessory DCC bus, which will be wired to the point motor housing just in case. I'd rather avoid putting leaving any electronics more than point motors and switches outside. I'm trying to keep all electronics in the control shed.

I'll post another update tomorrow night.

Cheers,

Pete.

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ba14eagle said:

I am very interested to see this trackbed construction technique being put to the test, after reading about it on here before. Your concrete sections look almost as bomb-proof as mine!

The electronics side of your construction has already gone past my mental capacity for things electrical, but Im really keen on seeing how this impressive looking project pans out. :D

Now your totally confused :lol:

Having said that this has got to work or else you could be getting the hammer drill out to break it all up again. An exspensive exercise.

Ian

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Pete, I'm with you on keeping the electronics in the shed. All my Accy Decoders are in there. The runs to my point motors are all less than 10 metres and I've wired them with solid core CAT5 cable. They work fine.

Have you seen IanR's work on using the motors from car central locking systems. He's been very successful, they are cheap, powerful and better suited to outdoor use than standard point motors. I must have a go with them myself and find out which of my Accy Decoders can operate them.

There's a full thread on Operating Points Outdoors in the Electrics and Wiring section.

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Hi Chris,

It's interesting to hear you have your point motors running on cat5. Are they standard solenoid or slow action "tortoise" motors? I'd be a bit concerned if the former, as Cat5e is nominally rated to 0.577 Amps, according to Wikipedia (http://en.wikipedia.org/wiki/Category_5_cable). Brian Lambert (http://www.brian-lambert.co.uk/Electrical.htm) states that an instantaneous current of 4 Amps can be drawen from a typical motor. You may well be in the position that this is instantaneous load causes no lasting damage to the cable. The second thing that concerns me with Cat5e is that it's single core, and with thermal cycling or manhandling, I'd be worried about it fracturing. I did have a play with multi-core 21AWG, and found that 100 metres was sufficient to prevent the motors from working, and 50 metres saw degredation of the motor operation. I've got point motors that run 40 metres out, and 40 metres back through common return, so I had to go with the safer bet of thicker cables.

This website, Brian Lambert, the Digitrax guide to DCC and Everard Junction have all been fantastic sources of information. I'm in a position where we moved into the house last summer, and I've got permission the build the railway as a one-off construction project. My other half will then really get into planting loads of cool stuff in the flower bed that will no-doubt make it look fantastic; but I can't go making major modifications and digging all her hard work up in a year's time. Hence my decision to go with steel-reinforced concrete and big up-front investment in wiring. Today, I laid 400 metres of bus cable. I've got another 1 km of bus cable on order. I'll put cat5e and 4-wire loconet for bus communication to the opposite end of the layout. Then I'm ready to solder droppers onto the bus wires. The funny thing is that this layout will be totally DC for the first 2 or 3 years as I have absolutely no existing DCC equipment, it will be quite an investment, and I'd really like to see how Railcom standardisation develops before investing in the current NRMI DCC standard.

Thanks again for all the advice. Sorry there are no pictures this time; I finished the work at 22:00 and it's starting to get dark in the evenings now :cry:

Cheers,

Pete

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