Suspension bridge (Steve Buxton ) - Pioneering for the Scouts


We would like to thank Steve Buxton of Northallerton, North Yorkshire who sent us the design for this bridge. The instructions show a single trestle upright but it can easily be adapted, either by using two trestle uprights on the banks or at intervals across the span.




Equipment


- 2 x 5m (15ft) spars (or longer if possible)
- 1 x 2.5m (8ft) spar
- 3 x 2m (6ft) spars
- light poles about 2m (6ft) long - enough to bridge the gap with a distance of about 0.5m between them.

For every light pole you have used you need a light rope (10mm) which is long enough halved to go between the top pole and the walk way with a couple of metres to spare. If you are building a very long bridge you may find that you only need to suspend 2 out of 3 of the walkway spars.

- 2 ropes for the walkway - long enough to bridge the gap with plenty to spare.
- 18 pickets (or 2 pickets and 16 large pegs)
- 2 logs or strong spars about 2m (6ft) long
- 16 lashing lengths
- 2 strops
- 2 x pulleys and ropes for handy billie

Method

The trestle:

Using 2 x 5m (15ft) spars, 1 x 2.5m (8ft) spar and 3 x 2m (6ft) spars, prepare the trestle as shown below.

Attach the suspension ropes. Halve each rope and attach it to the top bar using a clove hitch so that the cross over is on the bottom of the bar. When all the ropes are attached, push half the ropes to the left of the trestle and the other half to the right.

The walkway:

Lay out the two long ropes and mark the centre.

Working from the middle out, tie the walkway runners in using a marlinspike hitch. Once one side is complete, go back to the middle and work out the other way. It is essential that you work from the middle outwards as this ensures that the tensions for the marlinspike hitches are in the right direction.

Place one log or stout stave on one bank and anchor it with eight pickets or large pegs

Erect the trestle and use some of the suspension ropes as temporary guys.

Pass the walkway through the trestle until you have equal amounts on each side.

Tie off one end of the walkway using a round turn and two half hitches round the log.

Prepare a second anchorage on the other bank and tie the two strops round the log. Set in two pickets about 2m behind the anchorage and attach two handy billies to them. Tension the walkway ropes a little at a time, keeping the tension in the ropes as equal as possible. When the walkway ropes are tight, tie them off to the strops.

Take the suspension ropes and space them out along the bridge. Tie them off using a Harvester's hitch. To ensure that they do not slip off the rungs of the walkway, take the rope through the middle of the walk way, diagonally across the rung and up the outside. It is easier if you start at the middle and work outwards.

Go round the bridge tightening all the ropes until the walkway is stable and the bridge the right shape.

Note:

It is important that the walkway ropes are tensioned properly, otherwise when the suspension ropes are tightened, the bridge will bow upwards so much that you will be unable to walk across it under the centre trestle.