Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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IIODUIAR PORTABLE BRIDGE
Field of the Invention
The invention is in the f ield of portable bridge
5 structures and methods for mounting an~ demounting portable
bridges .
Bac l~ r ~-ul~d of the Invention
Special structures are often required on roads in
10 remote areas to cross gaps, such as waterways. A variety
of approaches are used to cross such gaps. On logging
roads, for example, creek crossings are often built by
laying a culvert in a stream bed and covering the culvert
with roAdway fill material. Bridges may be used on remote
15 roads to cross some gaps. On logging roads, it is often
convenient to build bridges out of timber.
Recently, it has been recognized that previous
methods of constructillg bridges and waterway crossings on
20 remote roads typically cause significant environmental
damage. It has been recognized that any disturbance of the
bed of a natural waterway may change forever the
suitability of the waterway for a particular species. For
example, salmon may no longer spawn along creeks that have
25 been altered by the introduction of culverts. When a
bridge is constructed of timber, the bridge nPrP~rily has
a limited life. Timbers sp~nnin~ the waterway usually
deteriorate and may eventually collapse into the waterway,
with adverse consequences to the biology of the waterway.
Remote roads pose special problems for the design
of suitable bridges and waterway crossings. Since such
roads are often temporary in nature, it is desirable that
they be relatively inexpensive to construct. In some
35 cases, such roads must be closed to public traffic after
commercial use of the road has come to an end.
Accordingly, it would be desirable if bridges and waterway
crossings on such roads could be made to be mountable and
demountable using common machinery and at relatively low
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c06t. Preferably, such crossings should also be reusable.
The conditions under which remote roads are used
typically necessitate a sturdy design for bridges and
5 waterway crossings on such roads. On logging roads for
example, heavily loaded trucks will typically make frequent
use of such crossings. In many areas, waterways are
subject to dramatic changes in volume, so that waterway
cros6ings must be adapted to avoid destruction under high-
10 water conditions. Si];nilarly, the method of mounting anddemounting crossings on remote road6 should be simple and
the, }n~nts should l~e capable of enduring transportation
under difficult conditions.
15 ~ rv of the Invention
The invention provides a portable bridge,
including a novel portable bridge support. The bridge may
be transported in lln~ Pmhled form and constructed from its
' ~n.,nts at a remote location. The bridge is adapted to
20 provide a sturdy road crossing capable of handling
commercial traffic on remote roadways. The bridge
~ts are adapted for simple mounting and demounting,
so that the bridge components may be reused.
The major components of the portable bridge
support are a masonry footing and a masonry wall. The
footing and the wall are provided with metal plates. In
one ~ ;r-nt~ the wall and footing are made of reinforced
concrete. The metal plates may be inlaid in the masonry
wall and footing. The plates may be made of steel. The
plates are arranged to facilitate assembly of the bridge
support and the bridge by welding various of the plates to
one another. The bridge support and the bridge may be
demounted by removing the welds between the plates. The
welds may be removed by air arcing, as described in more
detail below.
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In one aspect, the invention provides a method of
mounting and demounting a portable bridge. To mount the
bridge, the following steps may be carried out in an
appropriate order:
i) Form foundations spaced apart on either side
of a gap (for example, the gap may be a waterway
having banks and the foundations may be formed in
the banks of the waterway).
ii) Place a masonry footing on each foundation.
Each footing has a metal footing plate attached
to its upper surf ace .
iii) Place a masonry wall on each footing. Each
wall has a metal wall base plate attached to its
lower surface and a metal wall top plate attached
to its upper surface.
iv) Weld the wall base plate on each wall to one
of the footing plates on one of the footings, to
fasten each one of the walls to one of the
f ootings .
v) Place a metal girder (or girders) across the
top surfaces of the walls in contact with the
wall top plates and spanning the gap.
vi) Weld the girder (or girders) to the wall top
plates .
~o demount the bridge, the following steps may be
carried out in an appropriate order:
i) Remove the welds between the girder (or
girders) and the wall top plates by air arcing.
Air arcing is a process in which a stream of high
pressure air is used to remove melted weld
material. Typically, the weld material is melted
by forming an arc between a carbon rod and the
weld materia l .
ii) Remove the girder (or girders).
iii) Remove the welds between the wall base
plates and the footing plates by air arcing.
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iv) Remove the wall6 .
v) Remove the footings.
In mounting the bridge, a number of additional
steps may be carried o~lt. A bridge deck may be provided on
top of the metal girders. Road bed material may be
backfilled against the sides of the walls that face away
from the gap or waterway. An anchor may be provided to
anchor the walls. If one or more of these additional steps
are used in mounting the bridge, appropriate corresponding
steps may be used to demount the bridge, ie. the bridge
deck, backfill material and anchor may removed.
In another aspect, the invention provides an
assembled portable bridge support. The support includes:
a) a masonry footing;
b) a metal footin~ plate attached to the upper surface
of the f ooting;
c) a masonry wall;
d) a metal wall base plate attached to the lower
surface of the wall and welded to the footing plate,
to fasten the wall to the footing; and,
e) a metal wall top plate attached to the upper
surface of the wall.
If the wall and footing are made of reinforced
concrete, the footing plate, wall base plate and the wall
top plate may be attached, respectively, to the footing,
the lower surface of the wall and the upper surface of the
wall, by being integrally formed in the concrete of those
components of the support. For example, the plates may be
positioned in moulds for the wall and the footings so that
the plates become part of those structures when the
concrete is poured into the moulds and then hardens. The
plates may be held in the concrete of the footing and wall
by anchor posts embedded in the concrete.
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In another aspect, the invention provides an
assembled portable bridge made from two of the assembled
portable bridge supports described above; the supports
being placed apart from one another to form a gap. Metal
5 girders supported on the upper surf aces of the support
walls are then used to span the gap between the supports.
The girders may be w~lded to the wall top plates. An
anchor may be attached to the walls of the supports to help
hold the supports in place.
The invention also provides an unassembled
modular portable bridge support. The unassembled support
includes a masonry footing with a metal footing plate
attached to its upper surf ace . The other component of the
15 support is a masonry wall with a metal wall base plate
attached to its lower surface and a metal wall top plate
attached to its upper surface. The wall is adapted so that
it is positionable on the footing so that the wall base
plate is on top of the footing plate. The wall and the
20 footing may each be sized to fit within the box of a
standard dump truck, to facilitate transportation of the
portable support to remote areas.
In one aspect, the invention provides an
25 l~n~s~ led modular pc>rtable bridge. The bridge includes
a plurality of masonr~ footings, each having at least one
metal footing plate attached to its upper surface. The
unassembled bridge also includes a plurality of masonry
walls. Each wall has at least one metal wall base plate
30 attached to its lower surface and at least one metal wall
top plate attached to its upper surface. A number of metal
girders and bridge deck members are also be included. Each
wall is positionable on top of a footing, so that the wall
base plate on the wall is on top of a footing plate. Each
35 girder is positionable on the wall top plates to span a gap
between the walls. The deck members are positionable to
form a bridge deck supported by the girders. The walls,
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footings, girders and deck members may be sized to fit
within the box of a standard dump truck, to facilitate
tran6portation of the portable bridge to remote areas f or
assembly .
Brief DescriPtion of the Drawinas
Figure 1 is an isometric view showing an
assembled portable bridge support of the invention,
including the attachment of anchors to the wall.
Figure 2 is a partially fragmented side
elevational view in partial section showing one end of an
assembled portable bri dge of the invention, in which the
bridge spans a waterway.
Detailed Description
As shown in detail in Figure 1, the invention
provides an assembled portable bridge support 10. Support
10 includes masonry wall 12 and masonry footing 14. Wall
12 and footing 14 may be comprised of concrete (with
)1 UpL iate structural characteristics such as a minimum
compressional strength and maximum slump) moulded in forms
with appropriate internal rebar reinforcing rods. Bottom
surface 28 of wall 12 rests on top surface 30 of footing
14. Metal wall base plates 26 are attached to bottom
surface 28 of wall 12. Metal wall end plates 24 are
attached to the lateral end surfaces 22 of wall 12, to
reinforce and protect the end corners of wall 12. Wall
base plates 26 and wzlll end plates 24 may be made from
steel angle iron. Lifting eyes (not shown) may be attached
to wall end plates 24. Wall end plates 24 and wall base
plates 26 are present on both the front side 16 and the
back side 18 of wall 12. Metal outer footing plates 32 and
metal inner footing p] ates 34 are attached to top surface
30 of footing 14. Wall base plates 26 are welded to inner
footing plates 34 and outer footing plates 32, to attach
wall 12 to footing ~4. Metal wall top plates 21 are
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attached to top surface 20 of wall 12.
Wall 12 may be skewed on footing 14, to adapt
support 10 for use in a particular road crossing. The
5 positioning of footing plates 32, 34 and wall base plates
26 as shown in Figure 1 facilitate6 this flexibility in
mounting orientation, since a portion of the wall base
plates 26 will lie over a portion of each of the footing
plates 32, 34 irrespective of the alignment of wall 12 and
10 footing 14.
Anchor 40 may be attached to wall 12. The
requirement for anchor 40 will depend in part on the height
of wall 12. Anchor 40 is made up of rods 42, and cables 48
attached to eye 45 of rods 42 and buried log 49. Arrows 41
in Figure 1 point in the direction of buried log 49, shown
in Figure 2. Rods 42 pass through holes in wall 12. Nuts
46 and washers 47 on t~readed portions 44 of rods 42 may be
used to retain rods 42 in wall 12.
Footing plates 32, 34, wall base plates 26, wall
end plates 24 and wall top plates 21 may be attached to
wall 12 and footing 14 by being integrally formed in wall
12 and footing 14 wheL~ wall 12 and footing 14 are formed
from concrete. Plates 21, 24, 26, 32 or 34 may be held in
the concrete by one or more anchor posts (not shown)
attached to the plates 21, 24, 26, 32 or 34 and ~ d in
the precast concrete of wall 12 and footing 14.
In another aspect, the invention provides an
assembled portable bridge 50 made from two assembled
portable bridge supports 10; supports 10 being placed apart
from one another to form a gap (one half of the bridge is
shown in the partially fragmented view in Figure 2, with
bridge 50 spanning creek 64). Bottom surface 31 of footing
14 may rest on firm bearing material such as shot rock (not
shown) on foundation 62. In some locations, piles (not
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shown) may be n~ C~ry to provide a firm foundation for
footing 14. Each footing 14 has metal footing plates 32,
34 attached to its upper surface 30. Metal girders 52
supported on upper surfaces 20 of walls 12 span creek 64
between supports 10. Girders 52 may be joined to wall top
plates 21 by welds 53. Bridge deck 56 may be provided,
supported on deck supports 54 on top of metal girders 52.
Deck 56 and deck supports 54 may be bolted to girders 52.
Fill material 59 may be backfilled against sides 18 of
walls 12 that face away from the gap or waterway 64, to
bring the road level 5~ up to the level of deck 56.
Bulkhead 58 may be used to hold back fill material 59.
Bulkhead 58 may also assist in bearing lateral forces on
bridge 50. If nC~ Ss;~ry~ a wing wall (not shown) may be
constructed on either side of bridge 50 to help retain fill
material 59. Anchor ~0 may be attached by cables 48 and
rods 42 to walls 12, to help keep support lo in place.
Rip-rap 60 may be filled in along bank of creek 64 over
footing 14 and up aga.inst front side 16 of wall 12, to
.protect and stabilize supports lo. Some or all of the
welds may be waterproofed, for example with waterproofing
tape .
In one aspect, the invention provides a method of
mounting and demounting portable bridge 50. The following
steps may be carried out in an appropriate seguence to
mount bridge 50:
i) Form spaced apart foundations 62 on either
side of a gap (shown as creek 64 in Figure 2).
ii) Place footing 14 (which may be made of
reinforced concrete) on each foundation 62.
Bottom surface 31 of footing 14 may rest on firm
bearing material such as shot rock (not shown) on
foundation 62. In some locations, piles (not
shown) may be necessary to provide a f irm
foundation for footing 14. Each footing 14 has
metal footing plates 32, 34 attached to its upper
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surface 30.
iii) Place wall 12 (which may be made of
reinforced concrete) on each footing 14. Each
wall 12 has metal wall base plates 26 attached to
its lower surface 28 and metal wall top plates
21 attached to its upper surface 20.
iv) Weld wall base plates 26 on each wall 12 to
the footing ~plates 32 on one of the footings 14,
to fasten each wall 12 to one of the footings 14.
lo v) Place a girder 52 (or girders, at least part
of which are made of metal) across top surfaces
20 of walls 12 in contact with wall top plates
21, spanning gap or creek 64.
vi) Weld girder 52 (or girders) to wall top
15 plates 21.
To facilitate re-use of the components of the bridge, the
following steps may be carried out in an appropriate
sequence to demount the bridge:
i) Remove the welds (not shown) between girder 52
(or girders~ and wall top plates 21 by air
arcing. Air arcing is a process in which a
stream of h igh pressure air is used to remove
weld material that has been melted. Typically,
the weld material is melted by using a carbon rod
to form an arc with the weld material. Air
arcing may be used to remove weld material
without overheating and damaging the plates,
since the volume of air use to blow the weld
material away tends to keep the plates relatively
cool .
ii) Remove girder 52 (or girders);
iii) Remove ~elds 36 between wall base plates 26
and footing plates 32, 34 by air arcing.
iv) Remove walls 12; and,
v) Remove footings 14.
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To mount bridge 50, further steps may be taken,
including one or more of the following steps. A bridge
deck 56 may be supported on deck supports 54 on top of
metal girders 52. Deck 56 and deck supports 54 may be
bolted to girders 52. Fill material 59 may be backfilled
against sides 18 of walls 12 that face away from the gap or
waterway 64, to bring the road level 57 up to the level of
deck 56. Bulkhead 58 may be used to hold back fill
material 59. If n~ss~ry, a wing wall tnot shown) may be
constructed on either side of bridge 50 to retain fill
material 59. Anchor 40 may be attached by cables 48 and
rods 42 to walls 12, to help keep support 10 in place.
Rip-rap 60 may be filled in along bank of creek 64 over
footing 14 and up against front side 16 of wall 12. Some
or ~ll of the welds ma~ be waterproofed with, for example,
waterproofing tape. If some or all of these additional
steps are used to mount bridge 50, appropriate steps may be
taken to demount bridge 50, ie. deck 56, deck supports 54,
fill material 59, rip-rap 60 and anchor 40 may removed.
The components of support 10 shown in Figure 1
may be provided in an unassembled modular form. The
llni3c5~mhled support may include: masonry footing 14 with
metal footing plates 32, 34 attached to its upper surface
30; and, masonry wall 12 with metal wall base plates 26
attached to its lower surface 28 and metal wall top plates
21 attached to its uppPr surface 20. Wall 12 and footing
14 may be made of reinforced concrete. Wall 12 is adapted
so that it is positionable on footing 14 so that wall base
plates 26 are on top of footing plates 32, 34. Wall 12 and
footing 14 may each b~ sized to fit within the box of a
standard dump truck, to facilitate transportation of the
portable support to remote areas.
The components of bridge 50 shown in Figure 2 may
be provided in lln~cs~hled modular form. In this form,
bridge 50 may include a plurality of masonry footings 14,
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each having metal footing plates 32, 34 attached to its
upper surface 30. The l]n~omhled bridge 50 may also
include a plurality of masonry walls 12. Each wall 12 has
metal wall base plates 26 attached to its lower surface 28
S and metal wall top plates 21 attached to its upper surface
20. Walls 12 and footings 14 may be made of reinforced
concrete. A number of rigid girders 52 (which may be
metal, such as steel), bridge deck members 56 and bridge
deck supports 54 may also be included. Each wall 12 is
10 positionable on top of a footing 14, so that wall base
plates 26 on wall 12 are on top of footing plates 32, 34.
Each girder 52 is positionable on wall top plates 21 to
span the gap, such as creek 64, between walls 12. Deck
members 56 and deck support members 54 are positionable to
15 form a surface for driving on supported by girders 52.
Walls 12, footings 14, girders 52, deck members 56 and deck
support members 54 may be sized to f it within the box of a
standard dump truck, to facilitate transportation of the
portable bridge components in modular form to remote areas
20 for assembly.
As will be apparent to those skilled in the art
in the light of the foregoing disclosure, many alterations
and modif ications are po~,sible in the practice of this
25 invention without departing from the spirit or scope
thereof. For example, footing 14 and wall 12 may be made
of a material other than masonry. Accordingly, the scope
of the invention is to be construed in accordance with the
substance defined by the following claims.
