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# Three anchors each side, bridge level with top anchor - best triangular design ideas, please! :7D? Answered

Hello!

I'm a bit stuck on making a stable, theoretical bridge.

Rules:
No one piece can be longer than 10, no shorter than 1.
The bridge must span at least 8.

Imagine a gully:
\______/

There are three anchor points that you must use on each side - the highest is at the top, the lowest halfway down (not that that makes too much difference...).

You have 80 pieces with which to build your bridges - please can you lend me your noggin's as I'm having trouble coming up with ideas that will bear a load.
A regular suspension bridge or a tressle bridge won't work, as the joins for the pieces are not fixed solid - so you must use triangles / tension to support them. A bit like loose mechano, or whatever it is people have these days :7)

Do they still have lego?
I haven't seen a kid play with lego for ages... It's mostly P£3 and Sega Megadrives and stuff. tsk.

Thanks!
Claire.

[ed]
I just noticed a knex catagory. I guess that's mechano, right..?

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## 4 Replies

In the end, we decided on a design like an archway.

We live right next to Archway Bridge, over Archway Road, in Archway, London... so it was kind of stupid of us to not notice that earlier. #:o]

There's a bit of an odd shape that required us to form such complex supports, but if there is an X in that section, the bridge totally loses the definition of an old arch.
The stress is mostly taken by an "S", that occurs in the second section of the supports. This is risky, but add any more structure and it detracts from the Great Western Railway feel, eh?
http://i651.photobucket.com/albums/uu234/Target_Clan/gully_bridge_1.jpg
I reckon it will look good. Now we just gotta figure what to make it from...

Nonchalant repartee.

lemonie (author)2009-10-29

I should look in the K'NEX category - it's not Meccano!
What is this bridge thing for?

L

mathews (author)2009-10-29

We had a project like this a few years ago, and the designs that won the contest were triangular. They also had strong, snug anchors on the cliff edge, so be sure to measure the gulley.