The Swing Bridge - Pioneering projects for the Scouts



This is another project that used to rely on a cart wheel and axle. This is OK for those Groups that have such items buried in their stores, but most of us have to resort to more modern methods.




Equipment


- 2 x 4m (12ft) spars
- 1 x 2.4m (8ft) spar to go through the centre of the wheel
- 1 car wheel with tyre and inner tube removed
- 12 x light spars to use as treads
- 24 lashing lengths
- 2 x 10m (30ft) lengths of rope for controlling the bridge
- 2 x 5m (15ft) ropes
- 4 x 3m (10ft) ropes
- 1 x 1.2m x 1.2m (4ft x 4ft) sheet of 20mm thick plywood
- 2 large tent pegs and mallet

Method

Having chosen the location for your bridge, check that your main spars are long enough to reach across the river or ravine.

Position the wheel on the ground and mark its centre

Remove the wheel and dig a hole to take the butt of the 2.4m (8ft) spar. Sink the spar approx 450mm (18") into the ground. Check that your spar is vertical then backfill firmly around the butt.

Pass the car wheel over the spar and onto the ground.

The sheet of plywood needs 9 holes in it - the centre one being large enough that the 2.4m (8ft) spar will pass through it so that the ply can rest on the wheel. The other holes should be drilled as in the diagram.

Place the plywood over the spar.

Place the butt ends of the 4m (12ft) spars on the plywood either side of the vertical spar.

Lash one light spar between the butts of the 4m (12ft) spars.

Using the holes in the plywood, attach the 4m (12ft) spars to the plywood.

Lash another light spar between the other ends of the 4m (12ft) spars.

Tie the two 5m (15ft) ropes to the top of the vertical spar and then use them as guys to stabilise the vertical spar.

Space the remaining light spars evenly along the 4m (12ft) spars and then lash them in place.

Tie the two 10m (30ft) ropes to the bridge, one either side approx 2.4m (8ft) from the vertical spar.

The bridge can be swung across the river by pulling on these ropes. It will probably be necessary to place a log on the opposite bank under the end of the bridge to keep the walkway level.