21. The St Lawrence Seaway and the Confederation Bridge
By Doug Knight
The general theme is why the Saint Lawrence Seaway was constructed, and the general lack of environmental concern at the time, compared to the construction of the Confederation Bridge and the environmental concern of that project.
Why is there a Zebra Mussel and Purple Loostrife problem in the Great Lakes ? DRAW MAP
Ships from other parts of the world can access the Great Lakes through the Seaway. Any pollutant in the ship can be dumped in the Great Lakes.
Why have the seaway?
To transfer bulk cargo cheaply without transshipment.
What bulk cargo?
Grain from the Prairies to Europe
Iron Ore and Coal from the Midwest to the East Coast Industry
Pulp from the northern Ontario forests
How do you get grain from the prairies to Europe ?
Through Hudson Bay - short shipping season
By rail to the Great Lakes and ship to Europe, a total rise of 61 metres above sea level
Soo Rapids - 6.4 metres drop
Niagara Falls – mega drop
St Lawrence River Rapids – near Cornwall
Why not truck it to Montreal and then ship it?
Bushel = 35 litres Cubic foot = 28 litres
Grain truck holds 630 bushels (Semi holds 1300 bushels)
Train Hopper car holds 4000 bushels
In 1932, the largest Great Lakes grain ship holds 530,000 bushels (132 train cars, or 407 semi-trailers)
Grain is limited by volume - the problem is much worse in shipping heavy stuff such as iron ore. Transport by ship seems to be more efficient.
What are the problems with shipping
The Great Lakes have been an inland waterway for years. The great lakes do not have the swell of the ocean - can get rough, but ship design can be different - leads to the Great Lakes freighters - a barge with crew at the front and engine at the rear - 200 metres long.
The Welland Canal locks 261 m by 24 m by 9 m deep
The Soo Locks are about the same
At Prescott the locks are 78 m by 13 m by 4 m - OOPS
So we must trans-ship near Prescott to a small ship that is not efficient on the ocean
So we need to upgrade the locks and canals on the St Lawrence river to take a 233 m ship with a draft of 9 m
The Arguments Opposing the Seaway
Railways - would reduce their income
Coal companies - hydro electricity cuts their markets
Water companies - might reduce the water available for industrial use
No mention of any environmental impact as we know it today
The Project
Need a channel at least 9 metres deep
One way of getting adequate depth of water in a river is by building a dam, which raises the water level behind it - the other option would be dredging channels
A dam also gives you hydro electric power
Seems like a good thing?
All the bridges crossing the lower river had to be raised
The governments had to relocate road and highways
Created a new lake - Lake St Lawrence
Flooded about 16,000 hectares of farmland
Had to move 6,500 people
Abandoned six villages and two towns
There is always a cost
Most general freight goes by container ship today, and they are too big to go through the seaway. So most seaway traffic is the bulk cargo - in the first year 18 million tonnes passed through the seaway
The Seaway
Joint US-Cdn project built between 1954 and 1959
About 3,769 km long - open about 8 months of the year (using icebreakers and bubbling)
105 km of canals capable of taking ships 61 m wide by 8 m deep
15 locks for ships up to 233 m long 24 m wide by 9 m deep. It takes about 35 minutes to pass through one of the locks
3 dams
The Confederation Bridge
Why and where
PEI is an island. Connection before the bridge was by ferry.
Northumberland Strait is about 10 km wide and freezes in the winter. So the ferry must be an icebreaker.
Ferries are not that efficient.
In the real early days, in the winter, crossing was by ice boat - partly by boat and partly by walking pulling the boat - could stay in the boat and be pulled at twice the price.
Was it wanted?
In 1988, 60% of people in PEI voted for a bridge - 40% against
Against
Island way of life
Environmental concerns - especiallly lobster and fishing
Could it stand up to the ice?
Environmental Assessment
13 areas from
Marine plants and animals
Changes in tides and currents
Changes in ice conditions
Affect on fishing
Osprey nests in the NB approach
General Construction
Describe the general construction
Locate by GPS to accuracy of 2 cm
Prefabricate the components on the shore and move them to location by barge
Dredge the silt
Install hard point pads on bedrock - 15 tonnes
Pier base - 5400 tonnes - 22 metres across, 14-43 m high
Pier shaft with ice shield - 4500 tonnes - 14-43 m high
Main girder span - 7500 tonnes - 192.5 m long - HOLLOW
Hinged Drop-in span - 1200 tonnes - 60 m long
Hinging to handle the expansion of the segments
Approach segments on shore or in shallow water different details but same principles
Ice control
Describe how icebreaker works - rides up and breaks the ice by weight
Ice is strong against compression but weak against shear
Driveway - break up the ice by lifting
Ice shields lift the ice and break it up so there is no pressure on the pier shaft
Conclusion
PEI is now connected to mainland by 12.9 km bridge
40 m ASL - navigation span 60 m ASL
Life of 100 years
Two lanes with breakdown lanes
Hollow for cables and utilities and maintenance access
Soo Locks
Welland Canal
Seaway Profile
Ice Boats
Confederation Bridge
Bridge Span
Placing the Bridge Span
Building the components
Great Lake Freighter – Edmund Fitzgerald
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