doublecee Posted April 24, 2012 Share Posted April 24, 2012 So, I have decided to build a tunnel. I have the tunnel ends, and I know that I need to extend the base area on which the tunnel will sit... The question in, how do I BUILD the tunnel. It has to be 2 meters long, on a straight. I also know that it has to be water tight, so plan to build it around a length of black drainage pipe. I also want to line the inside wall with some white LED lights. At 2 meters long, it should be easy to clean with either a gauge master track rubber on a stick or the dapol wagon (or both). But how do I build the main "bulk" of the tunnel with a material that wont perish... I do know that I want to "dress" the hill a bit as its going to be the only true scenic in the garden, but not in the usual manner.... Im thinking of using some of those nice creeping conifers that spread out over a flat surface as oppossed to grow up... and that will be the main purpos of the tunnel, to provide a good base for the plant to establish over. So, whats the best way forward.... keeping everything safe and simple Ta Link to comment Share on other sites More sharing options...
doublecee Posted April 24, 2012 Author Share Posted April 24, 2012 so this is my idea.... fan out the base a tad, guttering for the main enclosure.... sealed and water tight. Then the main shape from carved Polystyrene which is then rubberised and then sealed with fibreglass cloth soaked in expoxy resin This is then coated in smaller peices of the cotswold bluff gravel and then from behind, a creeping thyme and other suitable dangly plants can come up and over the tunnel as they establish... I may opt for 1.5 - 2 min length Link to comment Share on other sites More sharing options...
IanR Posted April 25, 2012 Share Posted April 25, 2012 Quote Then the main shape from carved Polystyrene which is then rubberised and then sealed with fibreglass cloth soaked in expoxy resin I'm not sure but I've got a feeling that the resin may dissolve the polystyrene. I think you may be better using polyurethane foam. You can buy it in slabs from DIY stores and you can even buy the expanding variety in cans. Link to comment Share on other sites More sharing options...
doublecee Posted April 25, 2012 Author Share Posted April 25, 2012 cool. I have decided to do a materials test at the weekend (if this rain will ever let up....!) Finally got round to replacing my old Airfix GMR BR class 31 yesterday with the weathered hornby version, so dying to give that a run too.... but the rain and wind down here is just ruining all plans Link to comment Share on other sites More sharing options...
traingeekboy Posted April 25, 2012 Share Posted April 25, 2012 Every layout needs a tunnel. I've been plotting one of my own; your's looks amazing. For the record, mine will probably be amazingly slipshod. he he he Link to comment Share on other sites More sharing options...
fungus Posted April 25, 2012 Share Posted April 25, 2012 My main advice is to make sure it is accessible - I did and I haven't regretted it! Mice, slugs, woodlice and everything else will find their way in somehow, and may be impossible to remove without good access. My tunnel is about 5' long, goes under a path, was made by the cut-and-cover method capped with removable paving slabs on top of building blocks, and has a removable liner made with inverted guttering encased in expanding plastic foam with rope handles on top and the cosmetic portal attached at each end. A few pictures taken during construction are at http://fungusmodels.blogspot.co.uk/2011/08/tunnel.html" onclick="window.open(this.href);return false;. Good luck! Link to comment Share on other sites More sharing options...
chris Posted April 25, 2012 Share Posted April 25, 2012 Make sure you bond those joints before you build a tunnel over them. Link to comment Share on other sites More sharing options...
doublecee Posted April 25, 2012 Author Share Posted April 25, 2012 top of the list Link to comment Share on other sites More sharing options...
cleanerg6e Posted May 9, 2012 Share Posted May 9, 2012 I have heard that a tunnel should never be longer than two hand to elbow lengths. If you provide good access you can have it longer but try to bond the rails only once you've got the walls up. If you find you have trouble bonding the rails you will require a rethink on the tunnel construction. You could make a test tunnel to try out your idea of what you want then if it doesn't work out you haven't got a permanent structure that's unworkable. Trevor Jones has tunnels on his garden railway as says that his only regret is that he has rail joints in the tunnels and it extremely hard to rebond them if bonds drop off in the winter. Roy. Link to comment Share on other sites More sharing options...
silverking Posted September 23, 2013 Share Posted September 23, 2013 MODULAR TUNNEL? A few piccies which should explain my effort at a 4ft tunnel under a stream that flows into my pond. Link to comment Share on other sites More sharing options...
silverking Posted September 23, 2013 Share Posted September 23, 2013 MODULAR TUNNEL PART 2 Link to comment Share on other sites More sharing options...
doublecee Posted September 23, 2013 Author Share Posted September 23, 2013 Are you not tempted to line it with pond rubber on the outside just to make sure, because once those wood sides start to rot in all that moisture, you may find your seal is easily compromised, and then its back to the back ache of digging it all out again. Link to comment Share on other sites More sharing options...
traingeekboy Posted September 24, 2013 Share Posted September 24, 2013 my only suggestion is to put some re-railers / road crossing tracks in those tunnels. Link to comment Share on other sites More sharing options...
silverking Posted September 24, 2013 Share Posted September 24, 2013 Sorry Guys Forgot to explain the materials, the yellow stuff is mains gas pipe about 1 inch wall thickness and 8inch id, the white stuff is plastic fasia board cut to size and the track bed is 1inch tanalised timber treated to several coats of bitumin paint. All the joints are to be sealed with mastic and when the tunnel is in place it is covered with heavy duty builders membrane then buried.Hopefully this should keep out any water/soil ingress. Sorry for any confusion this may have caused.Regards Mick. Link to comment Share on other sites More sharing options...
Rossi Posted September 24, 2013 Share Posted September 24, 2013 Now, That looks like a tunnel! Maybe I missed something in another post, but is there an access for cleaning the track/clearing windswept foliage/animal droppings? All my hidden sections have a removable top. We have lizard droppings that form into hard pellets... One cause of the broken drive shaft I think on a derailed class 47 (mentioned in an earlier post). Or maybe I'm missing the perspective and it's all reachable at arms length. Link to comment Share on other sites More sharing options...
ba14eagle Posted September 24, 2013 Share Posted September 24, 2013 Mick How are you going to ensure the weight of the soil doesnt push the tunnel / boards out of alignment? Link to comment Share on other sites More sharing options...
silverking Posted September 24, 2013 Share Posted September 24, 2013 Hi Rossi I have got rather long arms but on a more sensible note, (do we do sense on this forum?) I can just reach the middle with my cleaner on a short stick.For everyday cleaning I'll use a rail mouted one pushed by an engine. Regards Mick. Link to comment Share on other sites More sharing options...
silverking Posted September 24, 2013 Share Posted September 24, 2013 Hey Ba14eagle The track bed is screwed up into the gas pipe and the strips of fasia board are just a bit extra. This tunnel is the one that was on my G-scale railway and has been buried for a lot of years so it should do the job ok. Thanks for your concern. Regards Mick. Link to comment Share on other sites More sharing options...
chris Posted September 25, 2013 Share Posted September 25, 2013 This looks great. A proper outdoor structure using materials that will last for years. Grif's idea of a rerailler is an interesting one. I'd have never thought of that. A thought on bonding. I have suggested elsewhere on here that tunnels may benefit from a belt and braces attitude to bonding and that two bonding wires should be added to each rail join, but looking at your photos has given me a different idea. We bond close to rail joins to keep them short and unobtrusive, in a tunnel they can't be seen. A bonding wire that runs from one tunnel mouth to the other wouldn't look out of place. The solder joints would be accessible and could be maintained. Link to comment Share on other sites More sharing options...
silverking Posted September 25, 2013 Share Posted September 25, 2013 Hi Chris The bit I forgot is the bit you mentioned but I can get over that problem by threading some cable through the tunnel and stapling them to the track bed and then solder to the next length of rail. Funny how someone see's what you were going to do but forgot to do it. If there is a vacancy for a remember engineer you have got first refusal. Thanks mate. Regards Mick. Link to comment Share on other sites More sharing options...
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