David Jeanes comments (September
2007):
You can see the link and pin
construction and how the lower chords and
the diagonals are all tension members, while the upper chords and the
verticals are all steel beams in compression.
This appears to be a Whipple Pratt Truss (with crossing
diagonals), according to the following two descriptions:
Pratt Truss
The Pratt truss was originally patented by Thomas and Caleb
Pratt in
1844. In its earliest form, the Pratt truss was a combination wood and
iron truss. The top chord and verticals acted in compression and were
made of wood, while the bottom chord and inclined members acted in
tension and were made of iron. This combination Pratt truss was built
through the 19th century and was cited as a continued form by bridge
engineers as late as 1908. The Pratt truss survived the transition to
metal construction and was widely built as an all-metal truss well into
the 20th century. In 1916, bridge engineer and historian J.A.L. Waddell
claimed that the Pratt truss was the most commonly used truss type for
spans under 250 feet.
Whipple Pratt Truss
The Whipple Pratt truss, also termed Double Intersection
Pratt
truss, added additional diagonals to the basic Pratt truss, which
extended across two panels, but kept the parallel top and bottom chords
of the simple Pratt profile. Squire Whipple’s double intersection truss
was patented in 1847. In 1863 John W. Murphy, chief engineer of the
Lehigh Valley Railroad, slightly modified the Whipple Pratt truss by
adding crossing diagonals. The Whipple Pratt truss was widely used for
long span railroad bridges.
http://www.ole.dot.state.ia.us/historicbridge/construction.asp
You can also see the stone arch over the pathway at the near
end, which
was wantonly demolished by the NCC a few years ago, and which I think
dates from the 1855 bridge, so was the oldest railway artifact in the
original City of Ottawa.
2.7 CAR Rideau River
Bridge
This was opened with the opening of
the CAR
into Ottawa on 13 September 1882. There are two excellent early
pictures of this structure in the National Archives. PA 12198
shows the locomotive Georgia on the bridge in August 1882 while PA
27315 shows locomotive 21 posed
with one passenger car in October 1893. The bridge was built by
the Toronto Bridge Company whose plate can be seen on both early photos
although it has been damaged by 1893.
BRC order 492
of 6 June 1905 authorized the
CAR to reconstruct the substructure and this work was approved by order
529 of 4 July 1905. After this time it had three through truss
spans of 133.75 ft. and a total length of 401 feet. Further work by the
GTR was approved by order 21525 of 20
March 1914. It seems the basic
structure survived until it was taken out of service with the opening
of the new Union Station on 31 July 1966.
2.8 CNOR Rideau
River Bridge at Hurdman
This bridge was authorized by BRC
order 7503 of 9 July 1909.
Order 7945 of 2 September 1909 approved the Hamilton Bridge Company Diagram A of 13
August 1909 being strain sheets. It was opened on 3 December 1909
and saw low use until closed with the abandonment of the CNR Hurdman
line in 17 June 1966.
2.9 CNOR Rideau
River Bridge at Federal
The CNOR bridge over the Rideau River
on the
Beachburg subdivision was authorized by BRC order 13668 of 18 May 1911
and
the plans were approved by order 14828
of
20 September 1911. It was
opened with
the opening of the line from Hurdman to Smiths Falls on 3 December
1913.
2.10 CNOR Greens Creek Bridge
This was authorized by BRC order 5584
of
12 November 1908 and
was opened to carriage on 3 December 1909. The centre steel
viaduct contained an 80' span, 3 60' spans and 5 30' spans, (410' x
65'). East approach consisted of 11 bents on sills, (150' x 52')
while the west approach contained 21 bents frame trestle
on piles, (300' x 53').
BRC order 28704 of 22 August 1919
gave CNR authority to reconstruct the bridge. This work was
completed and authority given to use the bridge by order 32770 of 21 August 1922. It is likely
that the east and west approaches were filled in at this time - an
aerial photo of around 1930 shows only the main viaduct.
The Greens Creek bridge was taken out of use and dismantled after the
closure of the line in 1939
2.11
CNOR bridges over the Carp, Mississippi and Ottawa Rivers and
Stoney Creek (Beachburg subdivision)
From Canadian Railway and Marine World,
December 1915, page 453.
On the Canadian Northern Ry.'s main
transcontinental line, about 35 miles west of Ottawa, are four closely
located bridges.
The first bridge, over the Carp River, consists of two 75 ft. half
through
girder spans with a 200 ft. truss span between them. The next crossing,
the Mississippi River, is of two 75 ft. half through and a 121½
ft. half through girder span, between the two 75 ft. spans. A mile
farther
down is the Stoney Creek bridge, which had three 85 ft. half through
girder
spans. The fourth is a long crossing over the Chats Rapids of the
Ottawa
River, and is made up of 10 deck girder spans, including 5 plate girder
spans each 115 ft. long, 2 of 121½ ft., one 200 ft. through
rivetted
truss and one 280 ft. through rivetted truss spans. The total weight of
the bridges is about 2,800 tons.
The masonry foundations were all in at the time the superstructure
contractor's men arrived on the job on June 20, 1914. The plant arrived
a day later and at the Carp River, driving piles and building falsework
started at once. The easterly girder span was first erected, then the
bottom
chords and floor system of the truss span, were placed in position as
fast
as the falsework was built. The trusses were erected by a locomotive
crane
after the floor system was completed. An air hammer was used for
driving
the piles, air being supplied by a steam compressor, which was also
used
for driving rivets. This bridge was completed so that the construction
trains
crossed on July 16, 1914, and track laying was started to the
Mississippi
bridge and completed so as to allow erection of that bridge to start on
Aug.
1, 1914.
A camp was established at this point and maintained until the erection
work was started at Chats Rapids, at which point a splendid camp for
use through the winter was built, and the men were made as comfortable
as
they could be at home. The river bed at the Mississippi is rock, so
that
a temporary timber bent trestle was erected, which permitted running
out
the girders on the cars, from which they were unloaded into place. The
centre
girders of the Mississippi River Bridge weighed 52 tons each, and were
erected
by using a gallows frame, in connection with the 50 ton locomotive
crane.
Piles were driven at Stoney Creek, on which a temporary track was
constructed, and the girders carried into place from a side track by
the locomotive
crane. These girders weighed about 25 tons each. This bridge was
completed
on Sept. 3. 1914, but a serious delay occurred after this. About the
time
the track was laid to Chats Rapids, the grader's locomotive upset in a
sink hole, and a very difficult job of rescuing it was accomplished by
calling in the Terry & Tench Co.'s erecting plant. The compressor
was set up, and the pile driver used to build a trestle across the sink
hole. Then
the big locomotive crane was used to pick up the locomotive and set it
on the track. This caused a delay of three weeks, and threw the
erection
of the Chats Rapids Bridge long into the late autumn and winter.
Work was finally started at Chats Rapids on Sept. 16, 1914, and a 25
ton guy derrick, having an 88 ft. mast and a 75 ft. boom, was erected
alongside the track, about 200 yards from the first or easterly span,
where a storage and sorting yard was established. The first span, 121
ft. deck girder, was erected after the temporary falsework was built,
by
using the same method as at Mississippi River. The next span was a 200
ft. through truss over deep water, running very swiftly, the bottom
being
rock with great boulders, making it very difficult to secure a safe
footing
for the piles. The piles used were 14 in. x 14 in. 50 to 60 ft. long,
sawed
British Columbia fir, with, cast iron points. They were driven into the
rock
by the air hammer, sufficiently to get a good bearing. In addition to
the
deep water and swift current at this crossing, immense quantities of
saw
logs were constantly being floated down the river to mills at Hull, and
other places, and it was necessary to keep watchmen day and night to
protect
falsework from destruction. On top of the falsework the bottom chords
and
floor systems of both the 200 and 290 ft. through spans were built, and
the
permanent track laid as the work advanced. From this track the trusses
were
erected by the use of the locomotive crane, the material being pushed
in
on cars by the railway locomotive from the sorting yard. The shopwork
on
these trusses was such that on the 290 ft. span the end posts, which
were
erected last, did not even require a wedge to be driven in order to
connect
them to the top and bottom chords. As all of the girder spans in this
bridge
were of the deck type, without cover plates on the top chords, the
greatest
care had to be used in handling them. The work of erecting this bridge,
which
was 1,589 feet long, was completed on Jan. 16, 1915, the camp abandoned
and
the plant shipped away. The falsework and a large part of the erection
equipment
was shipped to Troy, N.Y., to be used in building the Congress St.
Bridge,
across the Hudson River.
The falsework timber used in the whole of the above work was British
Columbia fir of the best quality, cut for the purpose. In addition
about 200 piles were purchased locally. Throughout the whole work there
was
not a single serious accident, and the health of the men was splendid.
The contract for the fabrication and erection of the above work was let
by Mackenzie, Mann and Co., to Canadian Allis-Chalmers Ltd., Toronto,
who sublet the erection to the Terry & Tench Co. Inc. of New York.
W.
H. Grant, Manager of Construction, Mackenzie, Mann and Co., had general
charge. C. T. Smith was Superintendent of the work for the Terry &
Tench Co., and much credit is due him for the successful carrying out
of the undertaking; Geo. Fisher was his assistant; Nicholas Dowd had
charge of the locomotive crane. About 60 men were employed throughout
the job, and were all hired locally. The contractors state that it
would be difficult to get a better working force of men together. The
weather in the summer was greatly in
favor of the work, but storms in the winter caused some delay.
2.12 QMO&O Bridges on the North Shore Line
The Quebec government hired two
photographers to record the bridges on the QMO&O on completion in
1878, Henderson to document the bridges between Montreal and Hull and
Livernois those between Montreal and Quebec. An album of
photographs survives in the National Gallery in Ottawa (call number
TG445.P57) which contains 24 photographs, 20 covering the line from
Hull to Montreal. They are arranged in sequence from Hull
towards Montreal as follows (mileages shown are those of the Lachute
subdivision measured from Montreal):
P71:003:1 Gatineau
River,
mile 115.9
P71:003:2 Upper Blanche
River, mile 109.4.
With 4-4-0 #17.
P71:003:3 Blanche River,
mile
106.1.
P71:003:4 Aux Lievres
River,
mile 100.2. In final stages of completion.
P71:003:5 Aux Lievres
River,
mile 100.2. With 4-4-0 #17 and 3 cars.
P71:003:6 Aux Lievres
River,
mile 92.7. Looking through the bridge with rails covered in snow.
P71:003:7 Little Blanche
River, mile 89.2.
P71:003:8 North Nation
River,
mile 84.6. Two locomotives back to back.
P71:003:9 Salmon River,
mile
72.8.
P71:003:10 Salmon River,
mile
72.8.
P71:003:11 Riviere au
Chene,
mile 64.3.
P71:003:12 Rouge River,
mile
62.0.
P71:003:13 Rouge River,
mile
62.0. With 4-4-0 and one passenger car.
P71:003:14 Ballast pit
with
4-4-0 #16, steam shovel and flat car, this is the only picture not of a
bridge.
P71:003:15 Calumet River,
mile 59.9.
P71:003:16 West side of
Lachute.
P71:003:17 West side of
Lachute.
P71:003:18 North River of
Lachute.
P71:003:19 St.
Scholastique
River. With 4-4-0, poor quality.
P71:003:20 Riviere aux
Mille
Isles. "Clark Reeves & Co. Phoenixville Bridge Works, Pa.
P71:003:21 Riviere des
Prairies.
P71:003:22 St. Maurice
River.
P71:003:23 St. Annes
River.
P71:003:24 Batiscan River.
The bridges were built by the Phoenix
Bridge
Company, Pa. and the pictures and make a wonderful record of a railway
under construction.
The bridges saw service on the QMO&O
and
later the CPR until they were rebuilt 1923-1925 in order to be able to
handle heavier loadings. This was recorded
in the Canadian Railway and Marine
World
June 1923, page 277:
Lachute Subdivision Bridges. - We are officially advised that the
following bridges on the Lachute Subdivision, Quebec District, are
being reconstructed:
Bridge 56.8, Kingly Branch. - Existing 37 ft. deck plate girder span to
be replaced by a 30 ft. I beam span.
Bridge 60.1, Calumet River. - Existing 50 ft. deck truss span to be
replaced by a 50 ft. deck plate girder span.
Bridge 62, La Rouge River. - Existing bridge, consisting of three 150
ft. deck truss spans, to be replaced by three spans of similar type and
dimensions, but of heavier structure.
Bridge 64.3, Riviere au Chene. - Existing 50 ft. deck truss span to
be replaced by a 50 ft. half deck plate girder span.
Bridge 67.2, Salmon Creek. - Existing 50 ft. deck truss span to be
replaced by a 50 ft. half deck plate girder span.
Bridge 72.8, Salmon River. - Existing 100 ft. through truss span to
be replaced by a 100 ft. deck plate girder span.
Bridge 79.17, Papineauville Creek. - Existing 18 ft. deck plate girder
span to be replaced by an 18 ft. I beam span.
Bridge 97.6, Trepanier Creek. - Existing 29 ft. deck plate girder span
to be replaced by a 25 ft. Bethlehem I beam span.
Bridge 80.1, Trepanier Creek. - Existing 30 ft. deck plate girder span
to be replaced by a span of similar type and dimensions, but of heavier
structure.
Bridge 84.6, North Nation River. - Existing bridge, consisting of one
150 ft., one 200 ft., and one 100 ft. through truss spans, to be
replaced by two 78 ft. and two 53 ft. deck plate girder spans and one
200 ft. deck truss span.
Bridge 89.2, Blanche Creek. - Existing 50 ft. deck truss span to be
replaced by a 50 ft. half deck plate girder span.
Bridge 92.7, Blanche River. - Existing 100 ft. through truss span to be
replaced by a 100 ft. deck plate girder span.
Bridge 106.1, Blanche Creek. - Existing present 50 ft. deck truss span
to be replaced by a 50 ft.-half deck plate girder span.
Bridge 109.4, Blanche River. - Existing 100 ft. through truss span to
be replaced by a 100 ft. deck plate girder span.
We are also advised that contracts have been let as follows:
To McKinnon Steel Co., Sherbrooke, Que., for fabrication of steel for
bridges 56.8, 80.1 and 97.6;
to Dominion Bridge Co., Montreal, fabrication and erection of bridges
62 and 84.6;
and to Canadian Bridge Co., Walkerville, Ont., for fabrication and
erection of the other bridges named above, and for the erection of
bridges 56.8, 80.1 and 97.6.
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