WO2003078739A1

WO2003078739A1 - Pre-assembled units to form an arch bridge or lintel

Info

Publication number: WO2003078739A1
Application number: PCT/GB2003/001051
Authority: WO
Inventors: Peter Christie
Original assignee: Peter Christie
Priority date: 2002-03-12
Filing date: 2003-03-12
Publication date: 2003-09-25
Also published as: AU2003214400A1

Abstract

A method of bridging a gap with a pre-formed rigid arch structure is described. The method comprises remotely assembling and securing together individual components of the arch structure on a temporary former which define the required arch shape, transporting the assembled arch structure to the site of the gap to be bridged and applying and fixing the arch structure to supports on either side of the gap.

Description

PRE ASSEMBLED UNITS TO FORM AN ARCH BRIDGE OR LINTEL

The invention relates generally to a method for bridging a gap with an arch that does not

require a temporary support structure to be provided across the gap.

Arched bridges are presently used to form a bridge across a gap and are built using voussoirs.

The voussoirs are positioned to form an arch shape so that the weight of the voussoirs holds

the arch together. Presently arch bridges are built using temporary supports which hold the

individual voussoirs in position while the arch across the gap is being constructed. When all

voussoirs are correctly positioned, the temporary supports are removed and the arch is self

supportive. Such arches are well known and were widely used in the past. However, the use

of temporary supports are expensive and has resulted in the declining construction of such

arch bridges.

The present invention seeks to provide a method for reducing the cost of constructing arch

bridges or lintels that are made of individual construction components.

Therefore it is an object of the invention to provide a method for constructing an arch without

the use of temporary supports which support the individual construction components while the

arch across the gap is being constructed.

It is a further object of the invention to provide a method for constructing an arch remotely

from the gap to be bridged. It is a further object of the invention to provide a method for transporting the arch from the

remote site to the gap and fixing the arch to supports such as foundations on either side of the

gap which the arch will be lifted onto, while all the time maintaining the shape of the arch.

It is a further object of the invention to provide a number of methods for joining together the

individual construction components.

According to a first aspect of the present invention there is provided a method of bridging a

gap with a pre-formed rigid arch structure, said gap having supports spaced apart to define the

gap and which will support said arch structure, the method comprising: remotely assembling

and securing together individual components of the arch structure on a temporary former

which define the required arch shape; transporting the assembled arch structure to the site of

the gap to be bridged; and applying and fixing the arch structure to said supports.

Preferred embodiments of fixation devices and insertion instruments according to the

invention will now be described in detail, by way of example only, with reference to the

accompanying drawings, in which:

Figure 1(a) shows a perspective view of a first embodiment of a construction component

according to the invention.

Figure 1(b) shows a perspective view of two adjacent construction components according to

the first embodiment of the construction component. Figure 2(a) shows a perspective view of a second embodiment of a construction component

according to the invention.

Figure 2(b) shows a perspective view of two adjacent construction components according to the second embodiment of the construction component.

Figure 3(a) illustrates a schematic perspective view of a snapshot of the process of securing together the construction component on a pre-formed surface to form the arch shaped panel.

Figure 3(b) illustrates a schematic perspective view of a snapshot of an alternative process of securing together the construction component on a pre-formed surface to form the arch shaped panel.

Figure 4 illustrates a schematic top view of the interlocking of the construction components using a combination of construction components according to the first and second

embodiments of the construction components.

Figure 5 illustrates a schematic top view of a particular embodiment of the joining mechanism

for two adjacent construction components.

Figure 6(a) shows a side view of a section of the pre-asscmbled arch illustrating an

embodiment according to the invention in which a gap is created between the joints of

standard construction components to form the shape of the arch and filled with a specially

shaped packer to keep the shape of the arch. Figure 6(b) shows a side view of a section of the pre-assembled arch illustrating an embodiment according to the invention in which a gap is created between the joints of

standard construction components to form the shape of the arch and filled with a jointing compound to keep the shape of the arch.

Figure 7 illustrates a schematic perspective view of a rib or template fixed to the sides of the outer construction components of the arch shaped panel.

Figure 8 illustrates a schematic side view snapshot of the process of positioning the arch shaped panel onto foundations on either side of the gap to be bridged.

The same items in different figures share common reference numerals.

Referring now to Figure 1 (a) of the drawings, a preferred embodiment of a construction component used in the method of the invention is shown, designated generally by reference

10. Construction component 10 comprises identical first and second end walls 12 and 13,

identical first and second side walls 14 and 15 extending perpendicularly between walls 12

and 13, and floor 16 extending the area defined by walls 12, 13, 14 and 15. Length L of first

14 and second 15 side walls and length K of first 12 and second 13 end walls will be dictated

by the requirements of the arch. Walls 12, 13, 14 and 15 together with floor 16 defines inner

volume 1 1. End walls 12 and 13 each contain a transverse hole 17 extending horizontally

from their outer surfaces to their inner surfaces, the position of which is identical for both first

12 and second 13 end walls. First 14 and second 15 side walls each contain transverse holes

18 and 19. Holes 18 and 1 9 extend horizontally from the outer surfaces of first side wall 14 and second side wall 15, to the inner surfaces of walls 14 and 15. End walls 12 and 13 may

contain more than one transverse hole, and side walls 14 and 15 may contain more than two

transverse holes. The number of transverse holes required will depend on the particular

requirements an arch, and will particularly depend on the lengths of end walls 12 and 13 and

side walls 14 and 15.

The positioning of transverse holes 18 and 19 will now be explained with reference to Figure

1 (b) which shows two identical construction components designated by reference 10' and 10"

which are identical to construction component 10. With reference to construction component

10' distances a' and b' are equal, a' and b' being the perpendicular distances between floor 16'

and holes 18' and 19'. The distance, parallel to floor 16', between holes 1 8' and 19' is dictated

by z'. The distance, parallel to floor 16', between holes 18' and 19' and their closest corner

which is perpendicular to floor 16' is dictated by x' and y' respectively. The radial distance

between adjacent construction components 10' and 10" is dictated by A. The distance between

hole 19' on construction component 10' and hole 18" on construction component 10" is

dictated by z'". The distances, x', y', z' and A are calculated so that x' + y' + A = z', where also

z' = z'", thereby ensuring that construction components in adjacent rows can be joined so that

their radial joints are staggered as described in relation to Figure 4.

Holes 17, 18 and 19 should be of sufficient shape and size to accommodate a securing

mechanism such as a bolt. Construction component 10 may or may not be arched along its

length 'L'. The advantages provided by the construction component being arched along its

length is discussed below in more detail in relation to Figures 6(a) and 6(b). In particular embodiments, floor 16 may be detachable. Embodiments in which the floor 16 may be

detached from the construction component 10 is discussed below in more detail.

Referring to Figure 2(a), an alternative embodiment of the construction component is shown,

designated generally by reference 20. Construction component 20 comprises of a first

elongate wall 210 having a first end 21 1 and a second end 212, and an identical second

elongate wall 220 having a first end 221 and a second end 222. Second end 21 2 of first

elongate wall 210 is joined perpendicularly to second elongate end 222 of second elongate

wall. Construction component 20 further comprises a first short wall 230 having a first end

231 and a second end 232, a second short wall 240 having a first end 241 and a second end

242, a third short wall 250 having a first end 25 1 and a second end 252, and a fourth short

wall 260 having a first end 261 and a second end 262, wherein first 230, second 240, third 250

and fourth 260 short walls are identical. Length L of first 210 and second 220 elongate walls

and length of first 230, second 240, third 250, and fourth 260 short walls will be dictated by

the requirements of the arch. First end 23 1 of short wall 230 is connected perpendicularly to

first end 21 1 of first elongate wall 210. First end 241 of short wall 240 is connected

perpendicularly to second end 232 of first short wall 230. First end 25 1 of short wall 250 is

connected perpendicularly to second end 242 of short wall 240. First end 261 of short wall

260 is connected perpendicularly to second end 252 of short wall 250. First end 221 of

elongate wall 220 is connected perpendicularly to second end 262 of short wall 260. A floor

270 extends the area defined by walls 210, 220, 230, 240, 250 and 260. Floor 270 with walls

210, 220, 230, 240, 250 and 260 define inner volume 280. Short walls 230, 240, 250 and 260

each contain a transverse hole 290 extending horizontally from their outer surfaces to their

inner surfaces. First 2 1 0 and second 220 elongate walls each contain transverse holes 291 and 292. Holes 291 and 292 extend horizontally from the outer surfaces of first elongate wall 210

and second elongate wall 220, to the inner surfaces of walls 210 and 220. Hole 290 on first

230, second 240, third 250 and fourth 260 short walls are positioned be directly opposite hole

291 on second elongate wall 220, hole 291 on first elongate wall 210. hole 292 on second

elongate wall 220 and hole 292 on first elongate wall 210 respectively. Although first 230,

second 240, third 250 and fourth 260 walls are identical, the positioning of their hole 290 may

not be equal and depends on the positioning of their directly opposite hole on first 210 and

second 220 elongate walls. Short walls 230, 240. 250 and 260 may contain more than one

transverse hole, and elongate walls 210 and 220 may contain more than two transverse holes.

The number of transveise holes required will depend on the particular requirements the arch,

and will particularly depend on lengths and L.

The positioning of transverse holes 291 and 292 will now be explained with reference to

Figure 2(b) which shows two identical construction components designated by reference 20'

and 20" which are identical to construction component 20 as described above in relation to

Figure 2(a). With reference to construction component 20', distances a' and b' are equal, a' and

b' being the perpendicular distances between floor 270' and holes 291 ' and 292". The

distance, parallel to floor 270', between holes 291 ' and 292' is dictated by z'. The distance,

parallel to floor 270', between holes 291 ' and 292' and their closest corner which is

perpendicular to floor 270' is dictated by x' and y' respectively. The radial distance between

adjacent construction components 20' and 20" is dictated by A. The distance between hole

292' on construction component 20' and hole 291 " on construction component 20" is dictated

by z'". The distances, x', y', z' and A are calculated so that x' + y' + A = z', where also z' = z'". Holes 290, 291 and 292 should be of sufficient shape and size to accommodate a securing mechanism such as a bolt. Construction component 20 may or may not be arched along length 'L'. The advantages provided by the construction component being arched along its

length is discussed below in more detail in relation to Figures 6(a) and (b). In particular embodiments, floor 270 may be detachable. Embodiments in which the floor 270 may be detached from the construction component 20 is discussed below in more detail.

It will be appreciated that the construction components may be any shape and size that permit

the joining of adjacent construction components, and can be filled with a suitable material (as described below) in order to provide an arch shaped panel which can be assembled remotely before being transported to and fixed to the foundations on either side of the gap which is to be bridged. The above construction components are merely illustrative examples of providing such construction components. For example, short walls 230, 240, 250 and 260 may not be equal. Further, different shaped construction components may be used. For example, the construction components may have the shape of a triangular prism, with the floor and open

end of the construction component being the opposite triangular sides of the prism. A further

example is where the floor and open end of the construction components take the shape of a

hexagon.

Referring now to Figure 3(a), a preferred embodiment of the invention is shown, and in

particular a method of forming an arch shaped panel designated generally by reference 30.

using a number of construction components 10 and pre-formed surface 31. Pre-formed

surface 31 comprises of a rigid rectangular sheet of material having a first end 32, a second

end 33 opposite and parallel to first end 32, a first side 34 and a second side 35 opposite and parallel to first side 34. First and second sides, 34 and 35, are arched along their length. The

dimensions of pre-formed surface 3 1 are equal to the dimensions of the arch structure that is

required to bridge a gap. Ends 32 and 33 would rest on foundations 81 and 82 of Figure 8 if

pre-formed surface 3 1 were to be positioned across the gap to be bridged. A number of

construction components 10 are placed on pre-formed surface 3 1 as shown and each

construction component 10 is joined to all its adjacent construction components. To join

adjacent construction components, transverse hole 17 (not shown) of a first construction

component 3 10 is aligned with transverse hole 1 7 (not shown) of a second construction

component 320, and transverse holes 18 and 19 of first construction component 310 are

aligned with transverse holes 18 and 19 of a third construction component 330. With the use

of a nut and bolt (not shown) for each transverse hole, construction components 320 and 330

are fixed to construction component 3 10 by passing the bolt the through the aligned transverse

holes 17, 18 and 19 of the adjacent construction components, and tightening the nut onto the

bolt.

The pre-formed surface on which the arch shaped panel is constructed may not necessarily be

a rectangular sheet; in particular embodiments an arch which doesn't have a standard shape

may be required. For example, an arch may be required that bridges a gap which has

foundations that are not directly opposite each other, nor parallel to each other, nor at the same

height as each other. In these situations an irregular shaped pre-formed surface will be

required. Therefore the pre-formed surface must have the shape of the arch which is required

to bridge the gap. Further, the pre-formed surface may not be a rigid sheet. For example, the pre-formed surface

could be formed by excavating the required arch shape from earth; the excavation being

provided with a solid skin, such as a concrete skin, to retain the shape and provide a surface

on which to construct the arch shaped panel. An alternative pre-formed surface could be

provided by a frame, such as metal or timber scaffolding, which supports a solid surface

having the required shape and dimensions, the solid surface being used to construct the arch

shaped panel.

As described above in relation to Figures 1 and 2, transverse holes were provided within the

construction components to enable adjacent construction components to be joined as

described above in relation to Figure 3(a). However, a number of alternative joining methods

and mechanisms to nuts and bolts can be used and are described below. Further, a

combination of joining methods and mechanisms could be used to join adjacent construction

components. For example, a construction component may be joined to its radially adjacent

construction components through the use of transverse holes and nuts and bolts. However, the

same construction component may be joined to its circumferentially adjacent construction

components through the use of an alternative joining method such as any of those described

below. Despite which joining method is employed, each construction component 10 is

positioned so that its first and second side walls 14 and 15 extend perpendicular to first 32 and

second 33 ends of the pre-formed surface. Arch shaped panel 30 is complete once the surface

area of pre-formed surface 3 1 has been covered with construction components 10 that are each

joined to all their adjacent construction components. As shown in Figure 3(a), a plurality of

rows (designated by 'A', 'B' and 'C ) of construction components 10 are often required to

increase the width of the arch shaped panel 30. Rows A, B and C increase the width of panel 30 by using a series of parallel rows of construction components, wherein the construction components between adjacent rows are aligned with each other, thereby forming courses of construction components 'D', 'E', T', and 'G'. The assembly is carried out in an area that is either adjacent, or remote from the site of the gap to be bridged. Although as described the pre-formed surface is the exact shape and dimensions of the required arch shape panel, it will be appreciated that the pre-formed surface may have dimensions which are greater than the required arch shaped panel in order to ease the construction of the panel.

Referring now to Figure 3(b), an alternative method of bridging a gap with a pre-formed arch is described. This method comprises forming at least two arch shaped panels 30' and 30" on a rigid pre-formed surface such as pre-formed surface 31', wherein pre-formed surface 31 ' is capable of being lifted onto the foundations on either side of the gap. Arch shaped panels 30' and 30" are constructed parallel to each other and extend the length of the pre-formed surface, thereby leaving an exposed section of the pre-formed surface 31' between the between the two arch shaped panels designated by the hashed section marked H. Pre-formed surface 3 1' with

arch shaped panels 30' and 30" will then be lifted onto foundations, and the construction components filled with material of suitable strength to increase the loading strength of the

arch shaped panel. The exposed portion H of the pre-formed surface will then also be filled

with a suitable material thereby completing the arch shaped panel. More than two arch shaped

panels may be used if required, and the exposed portions of the pre-formed surface between

the arch shaped panels can be filled with material as described above.

Referring to Figure 4, another preferred embodiment of the invention is shown, and in

particular an alternative method for forming an arch shaped panel designated generally by reference 40, using a combination of construction components 10 and 20, and pre-formed surface 31. A construction component 20 is positioned with second elongate wall 220

proximal and parallel to the length of first end 32 of pre-formed surface 3 1. First end walls 12

of construction components 10 are placed adjacent short walls 230, 250 of construction component 20 which are distal from, but parallel to first end 32. First 14 and second 15 side walls of construction components 10 extend perpendicular to the length of end 32 of preformed surface 31 . A series of construction components 10 are positioned extending towards a second end 33 of pre-formed surface 31 as shown, forming two rows of construction components 'P' and 'Q'. Rows P and Q are staggered such that construction components 10 between adjacent rows are not aligned with each other, thereby eliminating the courses of construction components as illustrated in Figure 3(a). The width of arch shaped panel 40 can be increased by using a series of parallel rows of construction components 10 and 20. An arch shaped panel constructed using the method described in relation to Figure 4 has a much more rigid structure compared to an arch shaped panel constructed using the method described in relation to Figure 3(a).

Referring to Figure 5, another preferred embodiment of the invention is shown, and in

particular a method of joining construction components. The method can be used to join

adjacent construction components 10, adjacent construction components 20, and / or a

construction component 10 adjacent a construction component 20. Figure 5 shows adjacent

first 12 and second 13 end walls of construction components 50 and 51 respectively. A key-

way is formed by identical recesses 52 and 53 in walls 12 and 13 respectively. The cross-

section of recesses 52 and 53 perpendicular to their length has the shape of a rhombus.

However, the cross-section of recesses 52 and 53 may be any particular shape which allows the insertion of a key 55 having the same shape as, but a slightly smaller length and cross-

sectional area than, the combined shape of the opposing recesses so that when inserted into

recesses 52, 53, key 55 holds construction components 50 and 51 together. Recesses 52 and

53 may vertically extend the height of the construction components 50 and 5 1 , although in

preferred embodiments recesses 52 and 53 extend vertically from the top of construction

components 50 and 51 towards the bottom of the construction components for a length which

is less than the height of the construction component; whereby key 55 rests on the bottom

surface (not shown) of recesses 52 and 53. As depicted in Figure 5 and the accompanying

description there exists only one recess within a wall of the construction component for

joining adjacent construction components. However, more than one such recess may exist in

order to increase the strength of the joints between the construction components.

An alternative embodiment of a joining device (not illustrated) is where one of the opposing

walls is provided with a projecting shape formed integrally with the construction components.

The shape matches and fits into the recess on the opposite face thereby holding the boxes

together.

The mechanisms described to join adjacent construction components together is by no way

limiting and preferred embodiments of the invention can use a number of methods to join

together adjacent construction components such as using bolts, studs, rivets, clips, adhesive,

bonding agent, glue, clamps and the like. Further, a flexible joint can be provided by

replacing the flat or recessed joint with a joint the shape of a cylinder, its axis being parallel to

the bottom face of the arch and the touching faces forming a closed joint. Referring now to Figures 6(a) and (b), another preferred embodiment of the invention is

shown, and in particular a method of forming an arch shape. In general, construction

components 10, 20 may be fabricated so that they are curved along their length L, thereby,

when they are joined using the methods described above, the arch shape is formed naturally.

The amount of curvature is specific to each arch being constructed, and therefore standard

construction components are also provided for use in the case where it is not practical to

fabricate bespoke construction components . When using a standard construction component

10 which is not curved along its length L, the shape of the arch created by the arch shaped

panel 30, 40 is achieved by incorporating a specially shaped packer 61 between first 12 and

second 13 end walls of adjacent construction components 10' and 10". as illustrated in Figure

6(a). Alternatively, the gap between first 12 and second 13 end walls of adjacent construction

components 10' and 10" can be filled with a suitable jointing compound 62 which will support

the arch loading when it has set, as illustrated in Figure 6(b).

Referring now to Figure 7, another preferred embodiment of the invention is shown and in

particular an alternative method of assembling an arch shaped panel 70 . Arch shaped panel

70 is similar to arch shaped panels 30 or 40, and is formed on the same pre-formed surface 3 1 .

However, when the material used for the construction component, or the geometry of the arch,

or a combination of the two, or any other reason makes arch shaped panel 70 difficult to

assemble and manage on account of its flexibility, the arch is stiffened using a framework 71.

Framework 71 is fixed to the construction components (not shown as individual components)

which lie proximal and parallel to either of sides 34 or 35 of pre-formed surface 3 1 , using the

method adopted for joining adjacent construction components. Framework 71 can be left in

place once arch shaped panel 70 has been secured to its foundations or can be removed depending upon requirements such as appearance, headroom below the arch, operational or

other needs.

Referring now to Figure 8, another preferred embodiment of the invention is shown, and in

particular a method of lifting arch shaped panel 30 onto foundations 81 , 82. The same method

can be used to lift arch shaped panel 40, or any other arch shaped panel of the like described

in this document. The size of arch shaped panel 30 is determined by its weight, and will in

turn depend upon the lifting capacity of the equipment that it is intended to be used for placing

panel 30 into its final position. However, because construction components 10 will have less

weight than a current solid construction component, and because they are joined together

before they are lifted, it is possible to lift large arch structures such as arch shaped panel 30

into place which would otherwise not be feasible. Panel 30 must form a complete arch so that

it can be lifted onto foundations 81 , 82 that have been prepared on either side of the gap

intended to be bridge. In preferred embodiments, arch shaped panel 30 will not have the

support of pre-formed surface 31 when lifted. Therefore the shape of arch shaped panel whilst

it is being moved is retained by means of a cradle designated generally by 80. However, pre¬

formed surface 31 may be lifted in conjunction with arch shaped panel 30 if required. Once

arch shaped panel 30 is secured to foundations 81 , 82, construction components 10 are

progressively filled with a material of suitable strength to enable the arch shaped panel to

carry any additional loading that is required for the arch to fulfil its primary function.

As mentioned above with respect to Figures 1 and 2, floors 16 and 270 may be detachable to

provide for various special purposes. The floor of an individual construction component may

be removed before or after the arch shaped panel is placed on its foundations. Construction components of the arch shaped panel may be filled with a material, as described above, to

increase the loading strength of the arch. However, the construction component with the floor

removed can be used to pass, for example, a service duct through the arch shaped panel. This

process may also be completed with a number of construction components which have had

their floors removed.

In an alternative embodiment, all floors 16, 270 can be removed from the construction

components 10, 20. It is possible with this embodiment to assemble the arch shaped panel on,

and secure the arch shaped panel to, a membrane that is strong enough to support the material

being used to fill the construction component in order to increase the load carrying capacity of

the arch shaped panel.

So far the description has been for a permanent arch. Where the construction components are

made of a suitable material they may be used on more than one occasion as a temporary

support which is provided to form a roof or debris screen for protection or other below the

area that the arch shaped panel covers. Where the arch shaped panel is used as a temporary

support, the construction components may be joined to adjacent construction components

using temporary joints, thereby facilitating the easy disassembly of the arch shaped panel and

allowing the reuse of the construction components.

Construction components 10 and 20 can be extruded, cast, welded or fabricated from sheets or

other, using a suitable material such as concrete, concrete reinforced with fibre or metal, fibre

reinforced epoxies, ferro cement, plastic, metal or the like. A stiffer construction component can be provided by incorporating webs or flanges or other

stiffeners in full or in part within the construction component. For example, a flange may be

positioned along or near all or part of upper free edge or corner, or a web/part web or

diaphragm/part diaphragm may be positioned across the diagonal of the construction

component or other. The stiffer construction component may be used either for the whole

arch shaped panel, or to strengthen parts of the arch shaped panel where it is required. For

example, the stiffer construction components may just be used at or near the foundations 8 1 ,

82 or at the crown of the arch shaped panel, or other.

With any of the methods described above, stonework or ornamental facing or other

ornamental features is provided by including the proper fixings within the required part of the

arch shaped panel.

Advantages in use of examples according to the preferred embodiments of the invention

include allowing large arch structures to be prefabricated before being lifted onto their

foundations. With current methods, only small arches could be prefabricated and then lifted

due to the weight of larger arches being greater than the lifting capacity of current lifting

devices. The use of hollow construction components, various methods for joining the

construction components before lifting them onto their foundations using the method

disclosed, and the method of filling the construction components with suitable material after

the arch has been mounted on the foundations, negates the need for temporary supports and

therefore greatly reduces the cost of building arched bridges.

Claims

CLAIMS:

1 . A method of bridging a gap with a pre-formed rigid arch structure, said gap having

supports spaced apart to define the gap and which will support said arch structure, the method

comprising:

remotely assembling and securing together individual components of the arch

structure on a temporary former which define the required arch shape;

transporting the assembled arch structure to the site of the gap to be bridged; and

applying and fixing the arch structure to said supports.

2. A method according to claim 1 , wherein said individual components are hollow units

having a plurality of sides, and an open top.

3. A method according to claim 2, in which at least one of the sides of each individual

component is detachable.

4. A method according to claim 1 , wherein said individual components are assembled

on, and secured to a membrane.

5. A method according to claim 1 , where there exists a plurality of rows of said

individual components, said rows of individual components being fixed relative to each other.

6. A method according to claim 5, wherein said individual components are generally

rectangular in shape and said rows run paral lel to each other.

7. A method according to claim 1 , wherein said individual components are not regular

in shape, but the shape of said individual components is such that they allow the interlocking

of adjacent individual components.

8. A method according to claim 1 , wherein the shape and dimension of said individual

components are bespoke, whereby the shape of said arch structure is formed by the shape of

said individual components.

9. A method according to claim 1 , wherein the shape and dimension of said individual

components are not bespoke, whereby the shape of said arch structure is formed by the space

between adjacent individual components.

10. A method according to claim 9, wherein the space between said individual

components is filled with jointing compound or a shaped packer that will support the arch

structure.

1 1. A method according to claim 1 , wherein said individual components each comprise a

flange along all of the upper free edges, or near a corner, to provide a stiffer individual

component.

12. A method according to claim 1 , wherein each individual component further

comprises a web across the diagonal of the individual component providing a stiffer

individual component.

13. A method according to claim 1 , wherein said individual components are joined to adjacent individual components with rigid joints.

14. A method according to claim 1 , wherein said individual components are joined to adjacent individual components with flexible joints.

1 5. A method according to claim 1 , wherein there exists a framework which is fixed to

the outermost row of said individual components in order to stiffen said arch.

16. A method according to claim 1 , wherein transporting the assembled arch structure to the site of the gap to be bridged comprises the steps of: fixing said arch structure into a cradle which retains the shape of said arch; removing said temporary former; and transporting said arch structure onto said supports.

17. A method according to claim 16, further comprising the step of progressively filling

said individual components with a material of suitable strength enabling the arch structure to

carry additional loading.

18. A method according to claim 1 , wherein said individual components are extruded or

cast welded or fabricated from a suitable material such as concrete, reinforced concreter with

fibre or metal, fibre reinforced epoxies, ferro cement, plastic or metal.