Confederation Bridge (aka the
Fixed Link) Tour
On October 22, 1996, my fourth year Civil Engineering class
took a trip to the Confederation Bridge (hereafter referred to as the Link)to
see the final stages of construction. This page is intended to chronicle
our tour of the link construction site, and not to detail the complete
construction of the link itself.
Upon arriving in New Brunswick, we boarded the ferry for the
trip to the link. Already, the Link was dominating the scenery.
The Link is 12.9 kilometres long, and will be one of the longest
continuous span bridges in the world. It links Cape Tormentine, New Brunswick
with Borden, Prince Edward Island. When it is finished, construction will
have required:
3 million tonnes of aggregates and stone,
340,000 cubic metres of concrete,
53,000 tonnes of reinforcing steel,
13,500 tonnes of post-tensioning cable,
8,000 tonnes of miscellaneous metal fabrication, and
139,000 tonnes of asphalt paving.
When we arrived in PEI, we were taken to the staging facility for
the bridge. This is where all the parts of the bridge were pre-formed in
concrete, and left to set. When they were ready, they were transported
to the site by barge, and put in place.
One of the first steps was to dredge the strait bottom down to the
bedrock in the places where the piers were to go, and place three concrete
'hard-points' on which a pier base would sit. The base, along with the
ice shield and span sections are placed by the Svanen heavy lift barge.
Witness the 'corrugation' of the concrete at the top of the pier
base.
The metal pipes on the pier base are used to pour Tremie concrete
(underwater concrete) to ensure that the pier base is firmly fixed to the
bedrock. The concrete comes out in small openings on the bottom of the
pier base.
The pier base is hollow so that once the base is fastened securely
to the bedrock, the base can be filled with an extremely dense concrete
mix that will help hold the pier in place. The extra mass ensures that
even if a ship hits it, it will not move. Once the base is in place, the
ice shield section can be placed atop the base. The shield is hollow inside
and fits over the base, and has matching 'corrugation' on the inside to
match that on the top of the base. This helps fix the base to the shield.
All the concrete for the bridge sections must be poured above the
ground, or it would be impossible to move them again. The sections stand
on concrete pilings when in the staging yard, and these pilings stand over
concrete tracks on which leavy lift vehicles (Lobsters, or Huisman? vehicles)
travel. The tracks have hundreds of 'teeth' off which hydraulic jacks on
the Lobsters push themselves along with.
Once the ice shield is in place, a match-cast template is placed
on top of it, and this fits the bottom of the main span section.
The main span is taken out onto the wharf like all the other parts,
on the back of a Lobster.
The Svanen then takes the span section out to be placed on top of
a pier. Once two adjacent main spans are in place, the Svanen takes out
a drop-in span to connect the ends of the two main spans.
We had the oportunity to take a boat out and see the piers up close,
where they stood in place.
While some of the piers use a steel sheathing on the ice shield
to protect it from ice damage, most of the ice shields are cast from high
strength concrete; this is twice as strong as the concrete used in the
rest of the bridge. This last ice shield uses the high strength concrete.
The ice shield is designed so that any ice that surrounds it will ride
up on the shield and break under its own weight.
Amoung the sites we saw out on the water was the Betty - L, the
crane barge that placed the hardpoints.
We then headed back to the staging area to head back home.
As we took the ferry back to Cape Tormentine in New Brunswick, I was
able to snap a few more shots of the Link.
For more information, check out the Strait
Crossing web page.
The information here was found on the Strait Crossing
web page, and in the information pamphlets we got after our tour.
All photos Copyright 1996 Alexander McClearn
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