This bridge is made from what is called C2080 chain (but a similar chain, called 81X, would be much cheaper, I just had a bunch of the C2080 on-hand) - the video needs a little better explanation, bu t I don't know what more to tell you than to show you - I'm not an engineer, I just wanted to get across the creek, so build at YOU OWN RISK!
The first step was to drill the end timbers and install eyebolts. Attach the length of chain you will need to cross the gorge, go to the other side, and pull it across with a rope (we used a $20, 2,000-lbs, hand-powered, cable winch, too). Attach it using connector links (AKA: master links) to turnbucks on the other side. Tighten the turnbuckles to make the strands "level."
I used 1/4" stainless steel carriage bolts and a few sizes of washers to attach THROUGH the inside links of the chain.
This bridge is 50-ft long and weighs about 550lbs. The strength of EACH strand of this chain is about 8,000 lbs, so theoretically it could hold 24,000 lbs, but the ends would have to be anchored to steel I-beams planted into about 50 tons of cement on each side, so DON'T be stupid and try to drive a truck/ATV over something like this.
You Should be able to buy 81X chain for around $4-$5 per foot (found it today on Ebay for $39.50 for 10ft box or 3.95/ft) - I'd also check the price of the carriage bolts on-line. Picking them up at the local "Big Box" was about 10-TIMES MORE expensive than buying them on-line.
My first thought was to do this with cable which would be MUCH CHEAPER (like 50-cents a foot from a cable supply company)- the problem was, I could not find a suitable manner of attaching the deck-boards.
Anyway, the total cost of this was around $750.00 and took 2 men about 12 hours to complete - this was out in the DEEP WOODS, so we had no power-tools other than a cordless drill, so if you get a couple of buddies, this could be done in a few hours.
I attached the boards after I set the chain. We had discussed attaching the boards then pulling the whole thing across, but decided it would be too tricky given the terrain we we in.
