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Tunnelling - seeking your collective wisdom


Joined: 1-01-70

Topics: 6

Replies: 6

Posted: Tue 28th Sep 2010, 3:44am
Tunnelling - seeking your collective wisdom

My wife and I have bought 2 acres of land and she's agreed to me building a railway on it. It is fairly flat but a lot of dirt is going to come out of the ground for the drainage and water-collection tanks. As we're not allowed to remove the dirt from the site, it is either going to be spread out over the land (what a waste) or heaped into a pile. Now what better way to make use of a big mound of dirt than to put a tunnel through it!?

This will be a bit like cut-n-cover tunnelling without the cut first, so I plan to put down the tunnel and have the contractors just pile the dirt on top. The question comes... What to use for the tunnel lining?

I have been quoted about NZ$1000 per metre for concrete storm-water conduit, or NZ$1400 per metre for corrugated iron. Yes, I was surprised that concrete was cheaper.

Either way, this sounds ilke a lot of money as I am likely to want around 6m to 7m. I'd also rather have it curved.

What is your collective wisdom on tunnel lining material? The amount of dirt on top is not going to be huge so it doesn't need to be that strong, but then nor do I want it caving in on me!

How much margin for mis-alignment would there be on concrete sections to make the joints something other than straight?

Or how else would you do it?

Any suggestions would be gratefully received.

Kind regards
John Oxlade
New Zealand

Replies To This Post


Joined: 1-01-70

Topics: 0

Replies: 6

Posted: Tue 26th Oct 2010, 7:23pm

Hello John,
The railway that was recently used for the Society AGM has a tunnel built upon level ground. It consists of concrete block walls supporting a roof. I am not sure of the roof structure, but I can find out. Each end of the tunnel has a brick built entrance wall and the soil is piled over the tunnel roof and block walls and retained at the end by the brick entrance.

If you email me at
I can send you a photo of the internal structure.
Hoping this is of some use, please do not hesitate to ask for more info.
Best wishes
Derek Payne (member 02094)


Joined: 1-01-70

Topics: 6

Replies: 6

Posted: Wed 19th Jan 2011, 12:21am

Just an update ... I will probably forget the idea of the tunnel (at least for now) as it would be rather "fake" in that the ground height variation isn't enough to justify one, AND it is expensive. I can also use the money for a third rail for those who still choose to run 5" gauge and haven't seen the light yet! :-)


Joined: 4-08-09

Topics: 27

Replies: 172

Posted: Wed 19th Jan 2011, 12:37pm

Hello John.
To 'hide' your railway, and break up the flat site, how about planting some large shrubs? They won't look as if you have headed for the only bump on the landscape, and if they are dense enough you might eventually have to 'tunnel' through them!
Best wishes
George Coles


Joined: 9-08-09

Topics: 14

Replies: 106

Posted: Thu 20th Jan 2011, 6:27pm

A cheap roof can me made using road side crash barriers that have been sold off. Very cheap in UK certainly - cut to the required width.

Frank Cooper


Joined: 1-01-70

Topics: 2

Replies: 7

Posted: Sun 23rd Jan 2011, 12:52pm

How about a willow tunnel? See:

for how it was done for a 5" gauge line.




Joined: 22-05-03

Topics: 18

Replies: 38

Posted: Sun 23rd Jan 2011, 10:18pm

Woodseaves Miniature Railway has a Willow Tunnel. See image in the gallery.

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