The present invention relates to a single lane portable steel bridge
of standard or extra width with stiffened steel deck units. More particularly this
invention pertains to a steel decking arrangement replacing the timber decking
arrangement used at present for constructing single lane, standard or extra
wide, portable steel bridge, components of which can be transported easily and
skilled personnel can instal and assemble steel deckings in lieu of timber decking
in no time.
A few foreign Patents have disclosed steel plate deck bridges such
as, for in stance, Wedelen US Patent No.4,831,675 dated 16.05.1988 dealt with
orthotropic steel plate deck bridge with a double rib system, which is a structural
steel member with a steel plate deck welded to a closed steel rib, the said closed
steel rib being further welded to an open steel rib.
German Patent No. DE 1658628 and the corresponding UK Patent
No. 1169492 of 1967 relates to an expansion joint between a bridge deck and an
abutment covered by a trapezoidal elastomeric strip in which are embedded
continuous or discontinuous metal or other anchor strips whose vertical webs
are notched at intervals, wherein adjacent anchoring nuts are joined by welded
on rods. The invention pertains to means for covering and rendering waterproof
expansion joints for road bridges and other civil engineering constructions.
Original single lane bridges found in India, popularly called Bailey
bridge, were designed and fabricated with timber decks only. Such wooden decks
necessitate replacement at regular intervals due mainly to natural wear and
tear, apart from the undernoted disadvantages -
i) high cost of well-seasoned timber and their increasing scarcity ;
ii) proneness to pilferage ;
iii) governmental ban on use of timber to prevent deforestation, and
iv) possibility of fire hazard, particularly during dry months.
Need was being felt for a suitable cost-effective, yet durable replacement of the timber
decks, which would benefit a number of agencies like Indian Army, PWD (roads),
Border Road Authorities, Indo-Tibetan Border Authorities and various State Governments,

particularly in the North Eastern States, and also Himachal
Pradesh, Uttar Pradesh, and Uttarakhand, wherein timber decks
were being used. Stiffened steel decking arrangement of this
invention offers near-permanent solution to the problems outlined
above.
Apart from the foregoing disadvantages, timber decking
arrangement suffered from yet another drawback. The stiffened
steel deck units of this invention can effectively replace only
the wooden deck and kerbs (Riband), without altering or affecting
other supporting arrangements.
The present invention aims at providing a satisfactory
solution to the difficulties and drawbacks encountered in
conventional portable steel bridge (Bailey Bridge) with wooden
decking systems.
The principal object of this invention is to provide a
single lane portable steel bridge of standard or extra width with
stiffened steel deck units in lieu of wooden decking systems.
A further object of this invention is to provide a
simple yet cost-effective way to replace timber decks of existing
portable steel bridge with stiffened steel decks.
A still further object is to provide a portable steel
bridge with stiffened steel deck units thereby obviating
replacement of component parts, particularly deck units, kerbs
or ribands, etc., at regular intervals as was usually needed in
steel bridges with timber deck.

Another object of this invention is to provide an one
time solution to avoid regular replacement of wooden decks in
steel bridges which is not only costly but also is a difficult
task as seasoned timber is becoming scarce day by day, consequence
of the ban on deforestation.
Yet another object of this invention is to provide a
steel decking arrangement for a portable steel bridge, in which
any one or more of the constituent components can be readily
replaced, repaired and/or substituted at ease in the event of
wear and tear due to atmospheric corrosion or due to development
of cracks or breakages from natural causes like earthquake, flash
flood, soil subsidence, etc., without affecting or sacrifycing
scarce natural resources like wood.
The foregoing objects are achieved by the present
invention which provides a single lane portable steel bridge
of standard or extra width with stiffened deck units which
comprises -
(a) panel with panel pin and sway braces ;
(b) bracing frame with bracing bolt, chord reinforcement
with short chord bolt, and male/female end post ;
(c) transoms equipped with transom clamp & raker ;
(d) said transoms in turn carrying stringers which may be
plain and/or of button type and

(e) base plate fitted with bearings on which rests the bridge structure,
characterized in that the said stringer units carry stiffened steel
deck, junction stiffened steel deck at one end of the steel deck
assembly, the said steel decks being held in place by means of
kerb unit(s), so that welding is avoided altogether.
Normally there is used six numbers of stiffened steel decks and one
junction stiffened steel deck per bay of the single lane bridge. The stiffened
steel decks may be for bridges of standard width, weighing around 126 kg, or for
bridges of extra width, each weighing around 159 kg, depending upon the width
of the bridge.
Be it steel deck of standard width, or of extra width, there is used
6 numbers of such decks per bay of 10 ft, with a single junction stiffened steel
deck per bay. The latter, namely, junction stiffened steel deck, for bridges of
standard width may weigh around 72 kg, and those for extra wide bridges, may
weigh around 91 kg.
The steel decks along with junction stiffened steel deck are placed
under kerb units, one on each side, for holding the decks in place. The individual
kerb unit usually weighs around 71 kg.
As a further development of the present invention, there may be
used one or more decks which are fabricated from steel chord/rod reinforced
polymeric bodies like high density polypropylene, which substantially reduces
corrosion and effectively resists action of water and chemicals, apart from offering
resistance to abrasion, wear and tear.
The present invention will now be further depicted by

means of the accompanying drawings, wherein
Fig.1 shows the portable steel bridge assembly with
stiffened decking and
Fig.2 shows perspective and sectional views of the
component parts of the deck units of this invention.
With regard to Fig.1, (1) is the panel, (2) is panel
pin, (3) is plain stringer, (4) is transom clamp, (5) is button
stringer, (6) is bracing frame, (7) is the male end post, (8) is
short chord bolt, (9) is bracing bolt, (10) shows bearings on
base plate(ll), transom is shown by(14), (15) is chord
reinforcement, (17) is sway brace, (18) is the kerb units for
holding steel decks in place, (19) shows junction stiffened steel
deck with varieties available for bridges both of standard and
extra width and (20) stands for stiffened steel deck with varieties
available for bridges both of standard and extra width.
Referring to Fig.2 of the drawings, (A) and (B) show
perpective view and sectional view of stiffened steel deck,
respectively, suitable for bridges both of standard width or
extra width, chosen depending upon the width of the existing
bridge; (C) and (D) are for perspective view and sectional view
of the junction stiffened steel deck, suitable for bridges both
of standard or extra width chosen depending upon the width of the
existing bridge, and (E) and (F) shows the view of the kerb angle
and the sectional view thereof, which illustrate the mode of
placement of steel deck units in a portable steel bridge.

The foregoing description of the subject invention
will be further amplified by the following Example which is given
by way of illustration and not by way of limitation.
Example
This typical example illustrates replacement of timber
decking arrangement including riband for a single lane (standard
or extra wide) portable steel bridge, in the following sequence
of operations :
(i) after removing the timber chesses, stiffened steel
deck units are placed in a manner as shown in Fig.l
of the drawings,
(ii) the stiffened steel decks are then inter-connected
with the newly introduced steel kerb unit and fitted
with tightening bolts.
The foregoing sequence of operations does not require
any change in or replacement of existing transom and stringer.
As already discussed earlier, the weights and dimensions
of stiffened steel deck units and the kerb units may be summarised
as follows :
Item Wt in kg Dimensions in mm
1. Stiffened steel
deck units
(a) For standard wide bridges 126 460X3485
(b) For extra wide bridges 159 460 X 4400

2. Junction stiffened
steel deck unit
(a) For standard wide bridges 72 230X3485
(b) For extra wide bridges 91 230 X 4400
3. Kerb unit 71 130 X 3040
Both for items 1 and 2 above-mentioned, the plate
thickness is optimally 5 mm and effective height is 45 mm. The
kerb unit carries recesses for insertion of securing means like
bolts and nuts, rivets or clamps for holding the stiffened steel
deck units.
The principal advantages of changing over from wooden
deck to the bridges equipped with stiffened steel deck units may
be outlined as under :
(i) in case of replacement of timber decking system, there
is no rejection or wastage of existing steel components
like stringers, transoms, etc. as they remain unchanged;
(ii) bridges with stiffened steel decks virtually are
semi-permanent structures compared to temporary nature
of timber-decked bridges ;
(iii) the steel deck plates are so designed that usually
there is no change in girder construction of the
bridge ;

(iv) reduction in maintenance cost due mainly to elimination
of routine periodic replacement of timber chasses and
ribands on account of wear and tear, pilferage, rotting,
pest attack, etc. ;
(v) though initial cost of stiffened steel deck units may
be slightly higher at present in comparison to timber
deck components, in the long run it is much more
economical due to elimination of recurring cost of
replacement of components and maintenance of timber
decks ;
(vi) replacement operation of steel decks needs very little
time, and
(vii) changing operation of steel decks is quite simple,
quick and there is no risk involved in assembling the
stiffened steel deck components.
The salient features of the present invention may be
briefly summarised as follows :
(a) stiffened steel deck units of this invention are suitable
to carry upto IRC Class-24R / Class 'B' loading only ;
(b) the existing transom and stringers may be kept unchanged;
(c) for replacement purposes, only timber components like
ribands, including bolts, and chesses are replaced by
stiffened deck units, and

(d) after replacement though there is an increase in weight per metre,
when compared to the timber-decked bridges, there is no change in
load class.
As the present invention may be embodied in several forms without
departing from the spirit or essential characteristics thereof, it should also be
understood that the above-described example(s) is not limited by any of the
details of the foregoing decription, unless otherwise specified, but rather should
be constructed broadly within its scope as defined in the appended claims and,
therefore, all changes and modifications that fall within meets and bounds of
the claims, or equivalences of such meets and bounds, are therefore intended to
be embraced by the appended claims.

We claim :
1. A single lane portable steel bridge of standard or extra width with stiffened
deck units comprising -
(a) panel (1) with panel pin (2) and sway braces (17) ;
(b) bracing frame (6) with bracing bolt (9), chord reinforcement (15)
with short chord bolt (8), and male/female end post (7) ;
(c) transoms (14) equipped with transom clamp (4) & raker (16);
(d) said transoms in turn carrying stringers which may be plain (3)
and /or of button type (5) and
(e) base plate (11) fitted with bearings (10) on which rests the bridge
structure,
characterized in that the said stringer units carry stiffened steel deck (20),
junction stiffened steel deck (19) at one end of the steel deck assembly, the said
steel decks (19 and 20) being held in place by means of kerb unit(s) (18), so that
welding is avoided altogether.
2. A steel bridge with stiffened deck units as claimed in Claim 1, wherein
normally there is used six numbers of stiffened steel decks and one junction
stiffened steel deck per ten feet bay of the bridge.
3. A steel bridge with stiffened deck units as claimed in

Claims 1 and 2, wherein the said steel decks(20) may be for bridges of standard
width, each weighing around 126 kg or may be for extra wide bridges, each
weighing around 159 kg, and having optimum dimensions of 460 mm X 3485
mm and 460 mm X 4400 mm, respectively.
4. A steel bridge with stiffened deck units as claimed in Claims 1 to 3, wherein
the junction stiffened steel deck(19) may be for bridges of standard width, each
weighing around 72 kg, or may be for extra wide bridges, each weighing around
91 kg.
5. A steel bridge with stiffened deck units as claimed in any of the preceding
claims, wherein the individual kerb unit for holding the steel decks in place
weighs around 71 kg.
6. A steel bridge with stiffened deck units as claimed in Claims 1 to 5, wherein
one or more decks are steel chord/rod reinforced polymeric bodies made from
high density polypropylene, which reduces corrosion and resists action of water
and chemicals, apart from offering resistance to abrasion, wear and tear.
7. A single lane portable steel bridge of standard or extra width with stiffened
deck units, substantially as hereinbefore described, with particular reference to
accompanying drawings and appended Example.

Heretofore timber decking was being used in making single lane
portable steel bridge, popularly known as Bailey bridge. Such bridges were used
and erected by various agencies like Indian Army, Border Security Force, Indo-
Tibetan Border Authorities and so on, to name just a few, in remote areas,
particularly in hilly terrain strewn with ravines, gorges and swift-flowing rivers.
The wooden decks required replacement at regular intervals due to natural decay,
wear and tear and pilferage, which posed a financial burden on the authorities
for agencies. Moreover, due to the National Policy of preserving forest cover and
timber wealth, timber decks are becoming scarce.
The foregoing difficulties have been overcome by the present
invention which replaces the timber decks by stiffened deck units of
predetermined dimensions.
According to this invention there is provided a single lane portable
steel bridge of standard or extra width with stiffened deck units comprising -
(a) panel (1) with panel pin (2) and sway braces (17) ;
(b) bracing frame(6) with bracing bolt (9), chord reinforcement (15) with
short chord bolt (8), and male/female end post (7) ;
(c) transoms (14) equipped with transom clamp (4) & raker (16) ;
(d) said transoms in turn carrying stringers which may be plain (3)
and/or of button type (5) and
(e) base plate(11) fitted with bearings(10) on which rests the bridge
structure,
characterized in that the said stringer units carry stiffened steel deck (20),
junction stiffened steel deck (19) at one end of the steel deck assembly, the said
steel decks (19 and 20) being held in place by means of kerb unit(s) (18), so that
welding is avoided altogether.