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| John Morgan (1976) |
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North Channel and the Swing Bridge
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The Swing Bridge between Goat Island and Manitoulin Island is one of
the few remaining structures of the original AER. Happily it will
probably be with us for a long time as it is both the only land means of
access to Manitoulin Island and has also been declared an Ontario Heritage
Site giving it some measure of protection from those who would modernise
access to the island. The bridge was started in late1912 when the
Foundation Co. was given the contract to build the piers and abutments.
The foundation work was completed by May 1, 1913 and in the words of R.S.
McCormick, Chief Engineer of the AER, was "a very fine job of pier work.
The bridge itself consists of two 70 ft. deck plate girder approaches
on the Goat Island (north) side and a single 60 ft deck plate girder approach
on the Manitoulin Island side. The swing bridge itself is a 368 foot
through swing bridge span. The swing bridge sits a clear 17.5 feet
above mean water level and provides a 160 foot opening on either side of
the central pier. 2,570 cubic yards of concrete went into the two
wing abutments, three intermediate piers and the pivot pier. The
protection piers for the swing bridge are set at right angles to the centre
line of the
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| Canadian Railway and Marine News (1913) |
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Swing Bridge Foundations
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bridge tangent and are composed of timber cribs filled with stone.
The water is 24 feet deep at the centre pier which is set on solid limestone
bedrock. The accompanying photo is taken from the October 1913 edition
of Canadian Railway and Marine World and shows the completed pivot
and protection piers prior to the erection of the bridge.
The following description of the bridge is taken from the October 1913
issue of Canadian Railway and Marine World. "The draw span
is 368 ft. long, c. to c. of end bearings, with trusses spaced 18 ft. 3
ins. c. to c., the length being divided into12 panels of 30 ft. 2 ins.
each with a central panel of 6 ft. over the pivot pier. The depth
of the truss varies from 30 ft. at the end to 57 ft. c. to c. of chords
at the centre over the pivot pier... The end posts, top chords and
main diagonal posts at the pivot pier are built of 21 in. web plates, 24
in. covers, 3½ by
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Courtesy Little Current-Howland Museum
Sheguiandah, Ontario |
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Swing Bridge Construction Crew
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3½ in. top Ls and 5 by 3½ in. bottom Ls. The lower
chords from end to end are built of 20 in. web plates with 4-3½
by 3½ in. Ls and with 13 in. side plates where necessary.
All intermediate diagonals, except where eyebars are used, are built of
18 or 20 in. web plates, with 4 Ls 3½ by 3½ in.; the verticals
are built of a plate and 4-6 by 3½ in. Ls where they act as hangers
and of 2-15" Ls where they act as post.
The floor system consists of stringers 53 ins. deep, riveted into the
floor beams 68 ins. deep, which are in turn riveted into the verticals
of the trusses. Top and bottom bracing is of Ls, designed for tension
only in the case of the top laterals, and for both tension and compression
in the case of the bottom laterals. Each portal consists of 4-7 by
3½ in. Ls latticed with 3½ by 3½ in. Ls, forming a
frame 3 ft. 9½ ins. deep with two plate braces. Transverse
bracing at intermediate points consists of 4 Ls 5 by 3½ ins. laced
with 3½ by 3½ in. Ls forming frames of varying depth according
to the height of the trusses. The transverse bracing at the centre
posts is arranged to allow room for the operator's house and consists of
frames similar to the intermediate transverse bracing, above the house,
and in addition heavy kneebraces connecting the 24 in. box girder supporting
the house. The centre posts are braced longitudinally by 3½
by 3½ in. Ls, which stay the two adjacent posts against longitudinal
flexure and at the same time allow the truss to adjust itself during erection
to two bearing points over the pivot pier.
The span while swinging turns on a pivot provided with steel and phosphor
bronze discs 25 in. in diameter, and is steadied by eight trailing wheels
running on a cast steel track 25 ft. in diameter. The main rack circle
and the track are cast together in 13 sections. The two main centre
girders are 105 ins. deep out to out of Ls, with 8 by 8 in. flange Ls and
18 in. cover plate and carry the dead load of the span to the pivot girders
6.5 ins. deep resting on a steel casting which bears directly on the discs.
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rcaldwell(howland)t.jpg) |
Courtesy Little Current-Howland Museum
Sheguiandah, Ontario |
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Swing Bridge Construction Nearing Completion
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While closed the ends of the trusses are supported by cast steel wedges,
which are driven by the operating machinery so as to bring a dead load
reaction under each end of the truss of 60,000 lbs., thus preventing the
end from rising from its support under certain conditions of loading.
Each truss is supported at the pivot pier by two wedges spaced 6 ft. apart,
but which are so adjusted that they take the live load only, the dead load
being carried by the pivot. Both the end and the centre wedges are
operated by worm gears driven by shafting from the operator's house, and
protected by cast iron casing, which is so arranged that the gearing runs
in a path of oil. The main pinion for swinging the span is cast steel
15 ins. in diameter keyed to the 7 in. main turning shaft, and suitable
gearing is provided between this shaft and the engine shaft to give the
required speed.
The power for turning the draw and for operating the end and centre-wedges
is supplied by a 25 hp. Fairbanks-Morse gasoline engine, located in the
operators house above the tracks at the centre of the draw, the main shaft
having a velocity of 220 r.p.m. and working the machinery through two friction
clutches. The turning shaft and the wedge driving shaft are each
provided with a jaw clutch, so that power can be transmitted to each as
desired by moving the necessary lever. A safety device is provided
for the wedge shaft, to prevent driving the wedges too far and injuring
the latching machinery, consisting of a cross head connected by levers
to the jaw clutch of the wedge shaft and so adjusted that when the wedges
have been drawn far enough it will have moved sufficiently to disengage
the jaw clutch and thus shut off power from this shaft. The ends
of the spans when closed are held in position by a latch located at the
centre of the end floor beams and which is so connected with the wedge
shafting that it is lifted from its socket when the wedges are withdrawn.
When the span swings, the latch strikes a projection on the socket casting
and is lifted, thereby disengaging a trip, which allows it to drop to its
original position, so that when the span is closing the latch rollers will
mount the inclined sides of the latch casting on the pier and drop into
the socket, thus firmly latching the span before the wedges are driven
home. All lengths of truss members are corrected to bring the lower
cords in a horizontal line with the bridge closed, and the wedges driven
to give a 60,000 lb. reaction at end of truss. The computed drop
in end of truss when the wedges are withdrawn is 1.4 ins.
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Courtesy Little Current-Howland Museum
Sheguiandah, Ontario |
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Little Current Swing Bridge
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The Canadian Bridge Co. was awarded the contract for this job, and this
part of the bridge is now being erected. Due to delays in delivery
of material from the mill, the bridge company will not compete this erection
until sometime in October."
The photo on the left was probably taken shortly after the bridge was
completed. The view is looking to the north. The eastern end
of the Turner yard can be seen at the top right of the photo with the spur
to the coal loading dock just below it. The causeway and small deck
girder bridge used by the AER to go from LaCloche Island to Goat Island
can be seen in the upper right of the photo. This portion of the
right-of-way is now use for the new Highway 6 realignment which was completed
in 1998.
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t.jpg) |
Courtesy Little Current-Howland Museum
Sheguiandah, Ontario |
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The Little Current Ferry
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Although the highway from Espanola to Turner was completed in 1929, the Little Current swing bridge remained rail only until November 1946
when post war Ontario Government iniatives resulted in an improved Hwy
6 and the paving of the bridge surface to support vehicular traffic.
This change made access to the island much easier and resulted in the closing
of the ferry, shown in the accompanying photo, which had previously
shuttled between Little Current and Turner.
The first ferry to serve Little Current was named "Hiawatha" and
had a capacity of twelve cars. In 1929 fairs were set at 75 cents per car
and 20 cents per passenger. The Hiawatha was originally built in 1874 for
ferry service between Dresden and Sarnia, Ontario. She was retired in
1924, but was reactivated in 1929 and sent to Little Current. Hiawatha served as
the Little Current Ferry until 1931 when she burned and sank off Low Island
north east of Little Current
The bridge continued
to serve both rail and vehicular traffic until the mid 80s when the tracks
were removed from Little Current. With rail service terminating at Turner
the bridge now carries vehicular traffic only.
More photos of the Little
Current Swing Bridge
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