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Suspension Bridge Facts
How long is the bridge?
It's the longest suspension footbridge in Ontario -- 126
metres long.
How high is it?
- It's 25 metres above the valley and stream
- More than 300 metres above Georgian Bay
- The towers are 11.5 metres high.
On a clear day, your can see 10,000 square ki lometres!
How strong is the bridge?
No one really knows exactly how much weight the bridge
could actually carry. What the engineers and the codes look at
is the most weight it might be expected to carry -- including the
most people that could fit on it, the weight of snow and ice, and
the effects of cold weather on the cables. Then they build it even
stronger.
WE DO KNOW... There can never be too many people on the bridge.
It could hold the weight of people standing tummy to butt, shoulder
to shoulder, stacked 4-high the entire length of the bridge.
- The foundations which hold the anchors are set in 40-cubic
metres of concrete. They're 4 metres deep in the ground and weigh
118,000 kilograms.
- The main cables are 6.35-cm. diameter galvanized bridge strands.
They're 187 metres long and weigh 3600 kgs each.
- Every 1.5 metres 1.27 cm. chain cable drops to support the
deck. As they get shorter, the bridge platform gets higher (closer
to the main cables). Each chain cable supports a steel beam,
on which the deck-planks are bolted. Bottom cables run through
the steel beams to control the sway and bounce.
- Each deck board is a 3-metre-long, 8-cm. timber. The boards
are bolted down with 25 bolts on each cross-beam. That's 1008
metres of boards and 2125 bolts!
How much will it swing?
The bridge is very flexible and will move with the wind
and your weight as you cross it.
Suspension Bridge Construction
Designed by R.J. Burnside Engineering , Collingwood, Ontario . http://www.rjburnside.com
Built by Owen King Limited , Walkerton , Ontario . http://www.owenking.on.ca/
Cost: $1 million
The builders of the Suspension Bridge met unique challenges with
ingenuity during the three-month construction.
The location posed some difficulty from Day One. While Scenic
Caves Road provides easy access to the North end of the site, the
South end could only be reached by driving down a steep ridge,
or "whale's back", from the Scenic Caves Nature Adventures
entrance. In winter. On mud.
In order to pour the foundation for the South tower and anchor,
eight heavy tandem concrete trucks needed to access the site. Since
it would easily slide out of control down the muddy track, it needed
to be held back by a Caterpillar D9 tractor, which made for an
ungainly -- but harrowing -- procession down the slope.
Once the builders had raised the towers -- a relatively simple
part of the operation -- the time came to actually get the cables
across the valley. You'd think this would be a job for high tech
equipment and expensive machinery, but the solution was remarkably
low-tech. To start with, they simply used a hunting bow and a spinning
rod. After attaching the fishing line to an arrow, they shot the
arrow to the other side of the valley. Once they found the arrow,
they pulled the line across tied to a heavier nylon kite cord.
A yellow poly line followed, then a 1.27 cm cable rated to 6804
kgs. Anchored at either end, this cable allowed the heavy main
cables to be slowly pulled across using pulley's every few metres.
The builders tightened and anchored the main cables, then a worker
slid down the cables on a sling, detaching the pulleys.
To install the down cables and metal I-beams, workers attached
a carriage to the main cables with pulleys and moved across, attaching
and dropping the down lines, three at a time. As soon as three
cross beams were in place, another brave crew sprang into action,
laying the decking and bolting it onto the beams. Remember that
they did this with no fencing on the bridge, and with the bridge
swaying considerably with the weight and wind. Finally, the crews
installed the bottom cables, followed by the railing and wire fence.
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