Why is there only one channel tunnel?

3652 Views 28 Replies 15 Participants Last post by dwb, Oct 18, 2006

dwb

Discussion Starter · Jan 23, 2006

(I do have a serious query at the end)

I was trying to lay track in a straight line and despite the use of a straight tracksetta and then the edge of a quality one metre level, I was still veering one way or the other after a meagre 4 or 5 feet. From where I was laying the track everything seemed fine until I made two checks:-

1) Can I still fit the other running line, platform and two outer tracks in the space left before everything falls off the edge of the baseboard? If not, start again.
2) If I walk to the end of the line and cast my eye can I see a kink? If yes, start again.

Twice these checks failed and each time the deviation was barely perceptible at the point it started, neither did the straight edges I was using show it up.

Whilst pondering on my difficulty of keeping straight over a distance of 12 feet I wondered how you got to the moon without missing by rather a long way. Then I decided that it didn't matter, you just kept adjusting your course so that you were pointed at the moon, after all it is rather large and you can see it. But then I wondered what if you can't see your target such as the other half of a tunnel. A fraction of a degree off and as the joke about the 2 man quote to build a tunnel goes - "If we miss, then you get two tunnels for the price of one".

I realised that the Chunnel builders probably used GPS and lasers. But I didn't think that GPS would work to the tolerance I needed, though a laser level was a possibility. A quick google showed that basic models can be had for about £20 from Amazon but that still seemed like overkill, so before nipping down to B & Q I tried one last ploy.

I performed my number 1 check above at 4 foot intervals and secured a 4 inch piece of offcut track where the outer rail should be. Then I got a long half inch wide measuring tape - the kind builders use, it's about 28 ft long and doesn't like to kink left or right - and laid it between the rails of the 4 inch offcuts. Now I was able to use the tape as a guide to laying the track I wanted without any further dramas. The result is completely straight - a bit like the track from the opening of Once upon a time in the west - but it's near enough and once a train is standing on it you don't notice.

Query:
Whilst on (or near) the subject of the channel tunnel, I was thinking of using it this summer but I don't quite understand why there is a reasonable price and totally out of this world price. What are you not getting for the cheap fare? I have heard that maybe you get to wait a lot for some trainspotting if you haven't paid the ransom. Is this true?

David

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dwb

Discussion Starter · #5 · Jan 24, 2006

Drawing a line is an interesting idea. One of the reasons I was having a problem was that I don't have a reliable edge to work off. The roof trusses in the house aren't aligned well enough!

I can endorse both comments on the Peco track gauge. That's what I used to space in from the edge of the board. For determining platform width I turned the gauge over and used the outside edges of the Settrack gauge. It's a shade over two streamline jumps if you see what I mean. I've no idea if the platform will be wide enough but I don't have to use it 9-)

David

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dwb

Discussion Starter · #8 · Feb 5, 2006

>Thread
I considered string / wool rather than thread. Thread would have been a good idea. The job is now done and the loop was closed last night. I think the second line which I "keyed" off the first is slightly straighter. I would post some photos if someone could tell me how to refine a URL to a particular image in a photo album. I have an outstanding question in the bulletin board forum.

David

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dwb

Discussion Starter · #10 · Feb 10, 2006

>debt that two of them could run up
Not at all. It's one of those "Buy one, get one free" deals.

David

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dwb

Discussion Starter · #12 · Oct 8, 2006

>Thread would have been a good idea. The job is now done and the loop was closed last night
Since posting this comment, I have switched to Peco code 75 but continued to use the "thread method". Today I picked up a "laser straight" device and checked to see how straight the track laid with thread actually is. It's pretty much spot on, but in future I will use the laser. It's a lot easier to see in the dim conditions in the loft. Just remember NOT to look at the laser; always point it away from you.

David

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dwb

Discussion Starter · #18 · Oct 11, 2006

>why is it important to lay track in a straight line to this degree of accuracy?
I don't know if this comment applies to me particularly but when you have a "tail chaser" it is important that you make both ends meet. It's a bit of a nuisance when you get to the end of a 16 foot length to find that you have drifted by half an inch or more. That can be the difference between getting round a bend or not.

David

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dwb

Discussion Starter · #20 · Oct 12, 2006

I found another way to make use of it last night. I wanted to place a point about 6 inches along from an existing turnoff. One of the tracks from this new point was to be aligned with a track from this turnoff. By placing the laser level so that it projected along in the rail in the rigt direction, I knew that the new turnoff was placed accurately once the laser beam was shining along the equivalent rail.

Once the new turnout was pinned in place, I was able to cut a piece of straight track to fill the gap.

David

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dwb

Discussion Starter · #23 · Oct 14, 2006

Here's an example of what you can see with a laser level. As you can see the track is not directly aligned with the crossing, but I'm not inclined to do anything about it now.

I am going to have to do something about the track on left. It is set to a strict 10 foot gap but I think it would be better the gap closed a little to give an even curve. This is the reception track for arriving goods trains. The widening gap in the middle distance is to accommodate the signal box for this end of the station. At the last count, I estimated it would have about 60 to 70 levers.

David

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dwb

Discussion Starter · #25 · Oct 14, 2006

>I can't see what the laser gains you over a simple piece of thread unless your light is poor.
Speed and simplicity. I've been down the thread route. Remember the laser thingy only cost £3.99 + batteries.

David

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dwb

Discussion Starter · #29 · Oct 18, 2006

>Seriously though, a chalk line has to be the way to go surely ?
All right, I give in, I confess. I'm a hopeless spendthrift and gadget freak. I promise not to do it again - NOT.

It was only a suggestion. It's a free country. If you want to mess about with chalk, which sends shivers down my spine just writing about it, go ahead, I won't stop you.

:mock seriousness: - whatever that is?
David

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