CA2349315A1 - Structural support for elevated railway - Google Patents

Abstract

A support structure for an elevated railway, for example an elevated linear induction motor (LIM) railway, includes separately formed open U-shaped support girders and multiple guideway slab elements made of reinforced concrete. The girders are typically pre-formed and then assembled atop of appropriate supporting columns before the guideway slab elements are individually mounted and aligned atop the girders. For an LIM railway, the top surface of the guideway slabs includes pre-formed lateral canted rail support surfaces and a raised central LIM rail support to facilitate the use of economical fittings to attach the carriage rails and LIM rail to the guideway, and integrally formed lateral parapets to provide derailment protection. A mold design and mold support apparatus are provided for forming the guideway slabs from reinforced concrete wherein the mold support apparatus facilitates support of the mold in casting and resting positions.

Description

Y:1SL00110785 CA\as filed spec 010511 A4 versi0n.wpd STRUCTURAL SUPPORT FOR ELE4~ATED RAILWAY
Field of the Invention This invention relates to structural support for railways, particularly direct-fixation-rail elevated railways, and more particularly to an econorr~ically attractive structural support system in which lengthy precast girders are set in place and allowed to settle, and then smaller precast guideway deck slabs are set in place atop the girders, connected thereto, and aligned. The guideway deck slabs are advantageously designed to include upper surface features that facilitate connection, canting and alignment.
Background of the Invention Elevated railways require structural support that accommodates curvature of the railway both horizontally and vertically. Manufacture of the structure, alignment of the rail supports and related portions of the guideway and proviision of the desired cant to the rail supports are expensive and time-consuming under prior practice. One reason for the problem is that, for reasons of economy, any girder/guicieway structure should be formed in discrete lengths that are as long as possible. In conventional practice, this gives rise to a number of disadvantages associated with propeir surfacing and alignment, partly because the guideway and underlying support girder are manufactured as a single integral unit that limits the practicable length, requires hand finishing of the uppermost surface(s), and does not permit the use of either optimum or inexpensive connection elements and other rail hardware. Furthermore, variations in camber and alignment caused by concrete shrinkage, creep, etc. that occur in the girder portion of the structure directly affect the geometry of the guideway itself, and frequently necessitate the placing of shims, etc. along the length of the guideway to compensate for such dimensional variations as the girder concrete sets.
Conventional structural supports for elevated railways of the linear induction motor (LIM) type are made up of units each of which compri:>es a concrete deck slablparapet structure (the "guideway") for the rail support and for mounting the power rail and LIM
reaction rail, and an underlying U-shaped girder that is farmed integrally with the guideway portion so as to form a closed box-like guideway/girder structure. The girders span longitudinally between vertical support columns in elevated segments of the railway. The girders with integral deck slabs are typically cast in sifu, and thus creep, shrinkage, etc.
in the girder negatively affect the geometry and alignment of the guideway deck for supporting the carriage rails and the LIM reaction rail. While manufacturing economies of scale would be obtained by making the girders as long as possible, it is easier to correct misalignment problems in shorter deck segments llhan in longer ones, so design compromises are necessary.
More specifically, the conventional girderlguideway structure is cast as an integral unit using an interior collapsible form to define the interior walls of the girder and the undersurfiace of the guideway deck slab, as well as external forms for the undersurface of the girder and the more or less upright surfiaces leaving, however, the entire top surface of the concrete in the guideway deck slab to be hand-finished, which is labour-intensive.
The upper horizontal surfaces of the parapets (the outeir walls) of the guideway also have to be hand-finished. Further, because of the hand-fini;>hing, it is necessary that the use of stud bolts, etc. protruding from the deck slab surface be avoided. This implies that the attachment elements for the rail support and for the LIM reaction rail embedded in the deck slab have to be inset female elements as illustrated in Figure 1, that threadedly mate with matching male bolts that are inserted once the (hand finishing is complete. The combination of male and female elements are expensive relative to the cost of stud bolts that could, were it not for the need to provide a smooth, flat finish, be embedded in the concrete before it has set.
Moreover, the rail support elements for a conventionally supported rail have to be trapezoidal in transverse section so as to provide an upper inclined surface to which the carriage support rail may be directly attached, thereby to cant the rail.
Because of the occurrence of creep, shrinkage, etc. in the girder (which conventionally includes the guideway deck slab as a top flange), the dimensions of an ideal rail support element for canting the rail cannot be predicted with confidence - shims, etc. are typically used to make the appropriate adjustments. A further problem is that the LIM reaction rail has to be positioned appreciably above the deck slab surfiace~ because of the geometry of the LIM reaction rail relative to the LIM motor on the underside of the railway carriage. This implies that the stud bolts supporting the LIM reaction rail have to extend appreciably above the upper surface of the guideway deck slab. As significant stresses are applied to the bolts as trains pass over the reaction rail, either the bolts have to be oversized or the risk of failure due to metal fatigue is higher than would be desired, simply because of the extent of unsupported protrusion of the bolts abovE; the deck slab surface.
Summary of the Invention According to a principal aspect of the invention, the girder and the guideway slablparapet units are separately precast. For that reason, the guideway deck slablparapet units (frequently referred to in this specification simply as "deck slabs") may be made relatively short (say, about 3 metres) while the underlying girder, which has a generally open U-shaped cross-section, may be somewhat longer than conventional girders (about 36 metres or possibly longer, instead of t!'~e conventional 30 metres). Note that for any given length, the overall weight of the opE;n girder is appreciably less than would be the case for the conventional integrated box-structure. Since the alignment of guideway segments is relatively easy if the individual deck slabs are relatively short, and the alignment once made will persist because of the absence of creep and shrinkage of the precast girder, the girder can be made as long as is convenient or economical. This implies that anywhere from about 10 to 30 deck slabs could be mounted on a single open "U" shaped girder.
The foregoing structural design according to tree invention entails a number of significant advantages. First, all creep, shrinkage, etc. in the girder that would result in changes in camber and dimension throughout its length, etc. are confined to the open "U"
shaped girder itself and have no effect on the separately formed guideway deck slab elements that will be mounted atop the girder. Since the guideway deck slab elements per se are relatively short, they can each be individually set in place and individually aligned along the trackway. It is not necessary to acljust cant for the rails, etc. on a continual basis over an elongate guideway structure;; it is easier to make individual adjustments to a series of deck slabs that can be assembled together sequentially over the longitudinal span of a girder. Furthermore, it is advantageous to permit the concrete of the girder to set in place and to postpone the installation of the individual guideway deck slabs until the girder has substantially cured, so that the guideway configuration is adapted to the girder as it actually exists in place rather than having to design the individual guideway elements to an expected final design of the girder structure that may or may not be realized in actuality, the latter design approach being required for conventional structures of the sort illustrated in Figure 1.
For use with an LIM-type elevated railway, the upper surface of the generally horizontal portion of the guideway deck slab/parapet element according to the invention is typically not flat but is formed in a predetermined fashion to provide or contribute usefully to three types of support, namely:
1. a canted concrete surface on which the rail support element may be mounted;
2, an elevated central mount for supporting the LIM reaction rail; and 3. a shoulder intervening between the LIM reaction rail support surface and the rail support surface, for providing containment of the rail carriages in the event of derailment.
Note that by providing an initial cant on the upper surface of the concrete for supporting the rail, each rail support element can be of generally rectangular parallelepiped shape, which is less expensive to manufacture than the individually canted rail support elements of trapezoidal cross-section that heretofore have conventionally been used. The wheels of a conventional rail carriage have flanges on the inside and are slightly canted. The canting of the rails is necessary or at least highly desirable to prevent the carriage wheels from "hunting", i.e. continually moving from side to side as the carriage moves along the track, and to maintain normality of the carriage wheel/rail reaction forces. Note also that the precast character of the deck slab and the provision of an elevated central mount for the LIM reaction rail imply that conventional and relatively inexpensive stud bolts can be embedded in the concrete of the deck slab when it is formed, and used later to connect rail support elements and undersupport for the LIM
reaction rail. Note further that because the concrete for the LIM reaction rail mount is elevated relative to the carriage rail support surface, the stud bolts supporting the LIM
reaction rail can extend upwardly from the concrete surface a much shorter distance than that required to support the LIM reaction rail in a conventional structure.
This advantage enables the use of smaller stud bolts or reduces the risk of support failure or both.
Note that the upper surface of the guideway deck slab according to the invention is formed, not hand-finished, leading to considerable cost savings in the manufacture of such guideway slabs. The guideway deck slabs (and the attached parapet portions thereof) may be formed using suitable forms for forming almost all of the surfaces; hand-finishing is required only for a very small pouring portal at a suitable location, e.g. along one lower side edge of one parapet, the forms being tilted to place this pouring portal at the very top of the cavity within the forms.
When the elevated railway is not of the LIN1 type, some but not all of the advantages of the present invention can be realized. The girder and the deck slabs can be separately precast, with the advantages entailed by so doing; particularly, almost all hand finishing is avoided, and alignment is both facilitated and also stable by reason of the preforming. Canting for the rail support elements can be formed into the concrete surface underneath the support elements, permitting thE: support elements to be relatively inexpensively manufactured of steel plates of rectangular cross-section.
However, some of the advantages directly associated with the elevated mount for the LIM
reaction rail will, of course, not apply if the railway is of the overhead catenary type or some other type not requiring a centrally mounted LIM reaction rail.
Further, if the railway need not be elevated, k>ut requires structural support at ground level or in a tunnel, the deck slab design according to the invention may be used.
In the case of installation at-grade, the deck slabs would be supported by a continuous foundation slab. In the case of a guideway located in a tunnel, the deck slabs would be supported by the tunnel bottom slab. In such a tunnel installation, the inclusion of parapet walls integral with the deck slabs may not be necessary, as the tunnel walls may provide sufficient protection against derailment. In such cases, the advantages of the invention obtained by the use of precast deck slabs of a type suitable for implementing the invention are obtainable.
SUMMARY OF THE DRAWINGS
Figure 1 (prior art) is a fragment section view of a girder fragment and slightly more than half of the upper track-supporting top flange of the integrated structure with attached parapet, for an elevated railway, manifesting conventional elevated railway guideway design known prior to the present invention.

Figure 2 is a schematic elevation view of a portion of an elevated railway support structure constructed in accordance with the principles of the present invention, illustrating the columns, girders, and deck slab components of the elevated railway support structure in generalized schematic form.
Figure 3 is a cross-section through a specimen girder suitable for implementing the present invention, for use in an elevated railway support structure of the type illustrated in Figure 2.
Figure 4 is a section view of a girder and deck slab component constructed in accordance with the principles of the present invention, for use with an elevated railway of the linear induction motor (LIM) type.
Figure 5 is a schematic fragment plan view of a sequence of deck slabs for a guideway according to the present invention.
Figure 6 is a fragment elevation section detail view of the joint between two adjacent deck slabs of the type illustrated in Figure 5.
Figure 7 is a schematic section view of a shear connection for anchoring deck slab members to the uppermost flange of the U-shaped girder of Figure 3.
Figure 8 is a schematic detail plan view of a grouted pocket for the shear connection of Figure 7.
Figure 9 is a schematic section view of a pair of deck slab forms for forming a pair of deck slab segments of the sort illustrated in Figure 4..
Figure 10 is an exploded view of the forms of Figure 9 and a support structure for supporting the forms.
Figure 11 is a schematic section view of an alternative elevated railway deck slab constructed in accordance with some of the principles of the present invention, for a level unbanked portion of the guideway, with accompanying supporting girder, wherein the elevated railway is of a type requiring no central reaction rail.

DETAILED DESCRIPTION WITH REFERENCE TO DRAWINGS
A portion of a conventional guideway (generally indicated by reference numeral 22) for an elevated railway is shown in fragment section viE;w in Figure 1. Such conventional guideway typically comprises a generally box-configured girder 26 with an integral top flange 28 that serves as the trackway support structure, differing from the U-sectioned girder and separately formed deck slab of Figure 4, for Example, discussed below. Figure 1 illustrates a fragment section of the top portion of one near-vertical wall or web 24 of the box-type guideway girder 26 whose generally horizontally disposed track support flange 28, somewhat more than half of which is illustrated in Figure 1, serves essentially the same purpose as the deck slab 18 of Figure 4, to be discussed below. The parapet 43, unlike the integrally formed parapet 42 of Figure 4 to be discussed below, is formed separately and attached by suitable means (not shown in Figure 1 ) to the top flange 28, but otherwise serves essentially the same purposes as the parapet 42 of Figure 4. Figure 1 does not illustrate the remaining web structure of girder 26 nor the bottom flange of the girder 26, which however in such bottom and other side portions resembles the bottom and other side portions of girder 12 of Figure 4 to be further described. The girder 26 in complete section is thus generally box-shaped. Also not illustrated in Figure 1 is an initial derailment constraint of some sort that would conventionally be provided to limit the transverse movement of the railway carriage if it became derailed; parapets 43 serve as ultimate derailment constraints and also provide sound abatement. The girder 26 is typically formed in situ, and the top surface 90 of the top flange 28 of girder 26 is hand-finished.
The girder 26 extends (spans) longitudinally 'from support column to support column; the columns 16 and cross-head supports 14 illustrated in Figure 2 are suitable for such purpose, although intended to illustrate the more typical dimensional relationships of deck slabs 18 and girders 12 of the present invention, to be further described below.
However, because the top flange 28 is formed integrally with the rest of the structure of the girder 26, each girder 26 is appreciably heavier than each girder 12.
Referring to Figure 2, a portion of an elevated railway generally indicated as 10, comprises a series of girders 12 supported on cross-heads 14 mounted atop longitudinally spaced columns 16. Atop the girders 12 are mounted a series of substantially contiguous deck slabs 18 that support the rails on which a train of rail carriages 20 rides.

The deck slabs 18 and the girders 12 are, according to one aspect of the present invention, preferably preformed of reinforced concrete. This design enables the deck slabs 18 to be relatively short in length compared to the length of the girders 12. In practice, girders 12 of up to 30 metres or more in length with deck slabs of approximately 3 metres in length have been found to be suitable for nnost elevated railway applications.
Of course the girders 12 may be replaced by other deck slab support means in the case of track guideway intended for surface use or for use in tunnels or the like.
In such cases it may be desirable, depending upon the application, to omit the girders 12 entirely and to provide relatively short support slabs to substitute for the near-vertical webs 32 (Figure 3) of girders 12, or it may be sufficient to have an underlying concrete base integrally formed and extending underneath the trackway. The combination of long girders with relatively short deck slabs, all made of preformed reinforced concrete, is economical to manufacture and relatively easy to align.
Each girder 12 may be generally U-shaped in section as illustrated in Figure 3. The near-vertical webs 32 of girder 12 terminate in expanded end flanges 34 whose upper faces 36 may be provided with connecting elements (not shown in Figure 3; see Figure 7 and related description below) for attachment to the deck slabs 18 that will rest on the upper faces 36 of the girders 12. For curved sections of the track, the webs 32 may be made of unequal height.
Figure 4 shows a representative deck slab 18 comprising a generally horizontally extending base 40 and side parapet walls 42. Each deck slab 18 is a single separately formed concrete structural unit. The specific connection elements for attaching the deck slab 18 to the girder 12 are not illustrated in Figure 4, but once these connections are made or are in the course of being made, the interface: between the undersurface 44 of the deck slab 18 and the upper flange faces 36 of welbs 32 of girder 12 are grouted to provide grouted joints 46. The grouted joints 46 connect the girder 12 and the deck slab 18 into an integrated structural unit.
Between the parapets 42, the upper surface of each deck slab 18 comprises a central elevated mount 62 with a top planar surface 63 .and side inclined flat surfaces 53.
The surfaces 53 are preferably slightly inwardly canted (typically with a 1:20 cant) to avoid "hunting" of the railway carriage wheels on the rails, and to maintain normality of the wheellrail reaction forces. Such canting is in accordance with conventional design, which, _g_ however has heretofore conventionally been implemented by providing specially formed rail support elements, as will be further discussed below relative to Figure 1. Rails 52 of the present invention lie on and are connected to rail support elements 55, and if required, aligned vertically and secured in place by shim plates 96 (Figures 4 and 5) and stud bolts 51 embedded into the concrete of the deck slab 18.
It will be noted that rail support elements 55 connected to the side surface portions 53 of deck slab 18 are depressed relative to a centrally elevated portion 62 above which linear induction motor (LIM) reaction rail support plates 74 are mounted by means of nuts 70 threaded onto stud bolts 72 suitably embedded and anchored in the elevated portion 62 of deck slab 18. The LIM reaction rail 66 is mounted by means (not specifically illustrated in Figure 4) that firmly fix the reaction rail 66 onto support plates 74 that are fixed above the central elevated portion 62 of the deck slab 18, separated by air space 64. Electric power for the railway carriages is supplied to power rails 38 mounted on mounting bracket assembly 57, fixed by bolts 76 engaging female threaded receptacles 60 embedded within the concrete of the left parapet w<~II 42 as illustrated in Figure 4.
Note that the side surfaces 53 extend inwardly of the rails 52 for a distance before terminating at shoulder 68 of the elevated central LIM reaction rail support mount portion 62 of the deck slab 18. The shoulder 68 on either sidle of the mount 62 functions as a derailment constraint, preventing or impeding the wheels of the railway carriage that have become inwardly derailed from moving laterally any further than the shoulder 68.
Parapets 42 provide further derailment constraint if that provided by shoulders 68 is inadequate.
For a number of reasons, conventional girders 26 are appreciably shorter than girders 12. There are three principal reasons for the disparity in maximum length between girders 12 and girders 26. First, as mentioned, since thE; top flange 28 is formed integrally with the rest of the structure of the girder 26, each girdE:r 26 will weigh appreciably more than each girder 12, even though the absence of parapets 43 from the initial casting affords some offsetting reduction in weight. As hoisting and transportation equipment are limited to a maximum load weight, a girder 12 (Figures 2, 4) of the same weight as a given girder 26 (Figure 1 ) can be appreciably longer. Consequently, for the girder and deck slab arrangement of the present invention, columns and cross-heads can be spaced further apart and fewer of them will be needed for a given job.
_g_ A second reason for keeping the conventional girders 26 short is that longitudinal alignment problems, especially with respect to rails, teind to become more severe as the length of a track guideway increases. As mentioned, the deck slabs 18 of Figure 4, being discretely formed, can be relatively short (say, 3 m in length) while the girders 12 can support many deck slabs 18 in end-to-end sequence, and may be as much as 30 m in length, or longer. The relatively short deck slabs 18 facilitate alignment, since each slab and its connections and rail support elements can be individually aligned without affecting the alignment of any other slab 18; it is much easier to align fewer elements over a shorter length of a deck slab 18 than to have to align all of the elements together on a relatively lengthy top flange 28 of girder 26. By contrast to the girders 12, girders 26 are typically no more than about 20 to 30 m in length.
Finally, because the upper surface 90 of the top flange 28 provides a flat bed for rail supports 80 on which rails 52 are mounted, and for mounting the central linear induction motor (LIM) reaction rail 66, it follows that any creep, shrinkage, etc. in the conventional girder 26 affects the geometry and alignment of the guideway slab (top flange 28) for supporting the rail 52 and the LIM reaction rail 66. The longer the girder 26, the greater the risk of intolerable misalignment of components due to creep or shrinkage of the concrete of which girder 26 is formed. By contrast, since the girders 12 and deck slabs 18 of Figure 4 are preformed, no significant creep or shrinkage problem arises -initial misalignment is minimized by the manufacturing procedure followed, and alignment of components and of any one deck slab 18 with its neighbours is relatively easy and permanent once the slab 18 is positioned in place on the girder 12 supporting it. The shorter length of each deck slab 18 relative to the typicall length of the girders 26 facilitates alignment; alignment of the deck slabs 18 can be effected one by one, and alignment of rail supports, etc. on any one deck slab 18 can be effected separately from the alignment on neighbouring deck slabs 18.
The conventional girder/guideway structure 22 of Figure 1 other than the parapets 43 is cast as an integral unit using an interior collapsible form (not shown) to define the interior surfaces of the girder and the undersurface of the rail guideway top flange 28, as well as external forms for the undersurface of the girder bottom flange and the slightly inclined upright wall (web) surfaces, leaving, however, the entire top surface 90 of the concrete in the guideway slabs 28 to be hand-finished. The upper horizontal surfaces of the parapets 43 of the guideway 22 also have to be hand-finished. Note that the hand-finishing of the upper surface 90 of the flat bed is labour-intensive.
Further, because of the hand-finishing, it is necessary that any protruding connection studs, etc.
be avoided;
no connection element should protrude above the surfiace 90 until after finishing. This means that the attachment elements for the rail supports 80 and for the composite insulator and bar structures 88 that support LIM rail 66 have to be inset female receptacles 50, 84 as illustrated in Figure 1. Eventually, matching male bolts 56, 86 have to be screwed into the female receptacles 50, 84 respectively. This combination of male and female elements is expensive relative to the cost of connecting stud bolts 51, 72 that could protrude from the upper surfaces 53, 63 of the guideway slab 18 of Figure 4, in which stud bolts 51, 72 may be cast and anchored in place when the slab 18 is formed.
It can also be seen from Figure 1 that the rail support element 80 shown for a typical portion of the track has to be trapezoidal in tran:>verse section so as to provide an upper inclined surface to which the rail 52 may be directly attached, thereby to cant the rail. As mentioned previously, canting at 1:20 is conventional to avoid track hunting by the carriage wheels on both tangent track (straight track segments) and superelevated spiral track (curved track segments). Because of the occurrence of creep, shrinkage, etc. in the girder 26 (which includes top flange 28 as the underlying rail support structure), the initial mounting of rail support elements 80 for canting the rail cannot be predicted with confidence to be acceptable after the concrete has fully set - shims, etc. are typically inserted to make the appropriate adjustments during tree post-finishing alignment stage.
By contrast to the foregoing, the requisite cant for the track support can be formed by inclining the upper surfaces 53 of each deck slab 18 (Figure 4).
Furthermore, as the deck slabs 18 can conveniently be shorter than the giuideway flanges 28 integral with girders 26, and as the deck slabs 18 can be preform~ed, thereby avoiding subsequent creep and shrinkage problems, the initial cant formed in the upper surface 53 of slabs 18 and the initial alignment of rails 52 and rail support elements 55, 74 for the structure of Figure 4 require little or no subsequent adjustment following installation of the slabs 18 on the girders 12; any adjustment required can be effected for each individual slab 18 as a whole when it is mounted on girder 12. Once the adjustment is made, it is secured by grouting the connection at grout joints 46.
A further problem with the prior guideway structure of Figure 1 is that the LIM
reaction rail 66 has to be positioned appreciably above the flat bed surface 90 because of the required position of the LIM reaction rail 66 relative to the LIM motor (not shown) on the underside of the railway carriage. This necessitates that the stud bolts 86 supporting the LIM reaction rail 66 have to extend appreciably above the upper surface 90 of the guideway flat bed 28. As there are considerable stresses applied to the studs 86 as trains pass over the reaction rail 66, either the studs 86 have to be oversized or provided with reinforcing sleeves or the like, or else the risk of failure due to metal fatigue is higher than would be desired, simply because of the extent of unsupported protrusion of the studs 86 above the flat bed surface 90.
By contrast, because deck slabs 18 are individually preformed, and the upper support surfaces thereof need not be coplanar, a centr<~Ily elevated portion 62 of the slab 18 may be provided on which the LIM reaction rail 66 and its immediate underpinnings 74 may be mounted, thereby avoiding any need for unreinforced protrusion of stud bolts 72.
Further, inexpensive stud bolts 72 may be anchored in the concrete of deck slabs 18 when the slabs 18 are formed, reducing both a component expense and a labour expense. Further, because of the inherent provision ~of a shoulder 68 on the elevated portion 62 of the deck slab 18, no separate initial derailment containment or limiting device need be provided for the Figure 4 design, where<~s a separate initial derailment containment or limiting device (not shown) may be required for the conventional Figure 1 design.
Also illustrated in Figure 1 on the parapet 43 are conventional power rails 38 for delivering electric power to the passing railway carriage's. Typically the power rails 38 and associated support structure are provided on one parapet only; the opposite parapet (not shown in Figure 1 ) would be a simple concrete structure without any inwardly directed supported structure of any sort (compare Figure 4, which so far as the power rails and support structure are concerned, may be essentially similar to what is shown in Figure 1 ).
In Figure 5, a sequence in plan view of three consecutive deck slabs 18A, 18B, and 18C is shown, slabs 18A and 18C only as fragments. It can be seen that the rails are mounted to the track support elements 55 that are bolted to the deck slab 18B
by means of stud bolts 51. The interconnection between these slabs 18A, 18B, and 18C is optional;
if the sequence of deck slabs is intended to be an integrated structural entity, then the joints between consecutive deck slabs will be relatively strong and rugged, possibly involving suitable metal or reinforced concrete interconnection. If consecutive integrity merely of the slab surfaces is required, then the joints between consecutive slabs may simply be grouted. In the exemplary configuration of Figure 5, a grouted joint 94 is provided between the ends 43 of consecutive slabs 18.
The schematic slab 18B illustrated in Figure 5 i:; not representative throughout of any deck slab that would be actually used. Rather, for the purposes of illustration, the left-hand side of the slab 18B illustrates a fairly closely spaced arrangement of rail support elements 55, whereas the right-hand side of the view illustrates a more widely spaced arrangement of rail support 55. The general principle of rail support is the same in each side of the schematic view of Figure 5, but it is to be understood that in a real guideway, the rail supports on the left-hand side of the deck slab would match those on the right-hand side. In practice, where the track is tangent track (straight), fewer rail supports 55 will be required at longer interval spacings (as illustratE;d in the right-hand side of Figure 5). For curved portions of the track, the stresses on the rails are higher and accordingly the rail supports 55 will be more numerous and more closely spaced (as illustrated in the left-hand side of Figure 5). Further, the overall shape of a deck slab for use in curved track (not illustrated) would typically complement the track curvature; the deck slab ends 43 would in plan view be slightly inclined to follow 'the radius of curvature, and the positioning of the rail support elements 55 would accommodate the curvature of the track.
In practice, assuming that an average rail support spacing for all curved track regardless of the degree of curvature would be suitable, it may be possible to cast only two different types of deck slab, one for use with tangent track and the other for use with curved track.
If, however, some adjustment in the number of rail supports for different degrees of curvature is considered desirable, or if the sides or ends. of slabs having different degrees of curvature require more than one curved slab to be rnanufactured, then three or more different deck slab designs with differing rail support spacing and different side and end treatment can be provided.
It is also required that each deck slab 18 be firmly fixed to the underlying girder 12;
for this purpose, rectangular apertures 98 are provided at spaced intervals along each deck slab 18. Conveniently, these rectangular apertures may be located between successive rail support elements 55.
Figure 7 illustrates a suitable means of interconnection between the deck slabs 18 and the girders 12. Tie groups 102 (see Figure 8), which are bundles of reinforcing steel bars (re-bars) tied together, are embedded into the concrete of the top flanges 34 of the girder 12 at spaced intervals that match the spacing of i:he apertures 98 on the deck slabs 18. This of course implies that for curved deck slabs and curved girders, the spacing will be closer together than will be the case for tangent track and straight supporting girders.
Once each deck slab has been set in place and aligned atop a given girder 12, grout is poured into the apertures 98 to form a grout plug 100 that can be hand finished at its upper surface. The grout plug 100 will fill the space between the underside of the deck slab 18 and the upper surface 36 (see Figures 3 aind 4) of the upper flanged portions 34 of the girder 12. The grout plug 100 also surrounds and bonds to the tie groups 102, thereby forming a secure composite joint between the deck slab 18 and girder 12. A
portion of the grouted joint 100 may provide a spacing grout layer 46 (Figure 4) to fill any gaps between the underside of the deck slab 18 and the upper surface 36 of the adjacent girder 12. This space will be expected to vary somewhat from point to point underneath the deck slab 18 in order to accommodate whatever adjustments are required to bring the deck slab 18 into its final alignment. Once the grout plug 100 sets, the final track support surface alignment is preserved on a permanent basis.
Figure 6 illustrates a portion of the grouted joint 94 between two adjacent deck slab members 18. To provide structural continuity, protruding reinforcing steel bars 95 can be embedded into the concrete of the ends 43 of the deck slabs, which when grouted form a reinforced composite joint.
Figure 9 illustrates schematically forms for the manufacture of a pair of deck slab elements. It is efficient and convenient to manufacture the deck slab elements in pairs, as illustrated in Figure 9, so that the pouring of concrete into the forms is efficient and so that the two concrete filled forms balance one another, Eliminating the risk of toppling and avoiding the need for any special support, other than a longitudinal divider between the forms.
Specifically, a longitudinal central form support panel or truss 106 is centrally mounted on a base 108 for separating a pair of balanced forms, each generally indicated as 110, from one another. Each form structure 110 may be divided into a top form 112 and a bottom form 114 defining generally the top and bottom surface shapes for the eventual deck slab 18 to be manufactured. In other words, the hollow cavity 116 within each of the form structures 110 conforms in its internal surfaces to the intended external surfaces to be formed on the deck slab 18. For simplification, some of the details of the surface configuration of deck slab 18 have not been illlustrated in Figure 9.
The line of separation between top form 112 and bottom form 114 (the adjectives "top" and "bottom"
being applicable to the intended top surface and bottom surface respectively of the eventual deck slab 18) is in the form designer's discretion, but should be chosen to facilitate easy separation of the bottom form from they top form once the concrete has been poured and has set within the form structure 110.
In order to pour concrete into the cavity 116, a pouring portal 120 is provided atop each of the form structures 110 and is positioned so that poured concrete will completely fill the cavity 116. To facilitate complete filling of the cavity 116 and to promote stability of the form structures 110, shims or roller supports or hinges 122 may be positioned underneath the lower outer corners of the form structurEa 110 as illustrated.
If hinges are used along with suitable angled form supports (not shown in Fig. 9), each form structure 110 may be pivoted about the hinges to assume a generally horizontal orientation to facilitate separation and removal of the top form 112 from the bottom form 114 once the concrete has set. Although the form structures 110 are shown as being slightly out of contact with the vertical form support 106 in Figure 9, they may in fact tilt inwardly sufficiently that the upper portions thereof make contact with the upper portion of divider 106.
Since the particular configuration of a given dleck slab 18 will not be uniform throughout the guideway but will vary from point to point along the guideway, depending upon whether the guideway at a particular location is supporting tangent track or curved track, etc., a number of different shapes and configurations of form structure 110 may be provided to form as many deck slab shapes as are required for any particular guideway.
Alternatively, individual form structures 110 may be provided with individually adjustable means (not shown) for accommodating differences in intended deck slab configuration.
For most purposes it will probably be desirable to have individual form structures that do not require alteration. Therefore, a number of different types of form structures will, in most cases, be provided to make possible the manufacture of a number of different configurations of deck slab. In the simplest case, as few as two different deck slabs need be manufactured, one for curved track segments and the other for tangent track segments.

Figure 10 is a more detailed exploded view of a suitable support structure for the forms and of the individual form components themselves, thereby illustrating a convenient and effective implementation in a more detailed fashion of the arrangement illustrated in a simpler schematic fashion in Figure 9. Each form structure 110 shown in Figure 10 comprises a top form 112 and a bottom form 114, as dliscussed with reference to Figure 9. Again the interior surface 164 of each top form 112 has been somewhat simplified in Figure 10; the shape and configuration of the form 112 will of course be adapted to the particular top configuration required for each deck slab 18. The top forms 112 are provided with bolt holes 132 for alignment with mating bolt holes 134 in the bottom form 114, thereby permitting the forms 112, 114 to be securely bolted together to enable the concrete to be poured into the interior cavity 116 formed when the top form 112 and bottom form 114 are bolted together.
The uppermost surface of each top form 112, as illustrated in Figure 10, is formed as a trough 136 into which concrete can be poured. The bottom portion of the trough 136 is open to the interior of cavity 116 when the forms 112, 114 are bolted together, thereby constituting the pouring portal 120, as discussed with reference to Figure 9.
Further, Figure 10 illustrates end trusses 124 each having a base plate 108 and a vertical central stud 126, along with whatever struts are considered suitable to the integrity and required strength of the truss 124. The two studs 1126 also serve as the vertical end portions of a rectangular truss 128 extending between and consisting in part of the end studs 126 and serving as a suitable specific implementation of the vertically disposed form support 106 illustrated in Figure 9.
The end trusses 124 may be provided at their lovuermost end portions with flanges 166 for attachment to an underlying platform, or the like (not shown), in order to stabilize the truss arrangement illustrated.
A jig (not shown) may be provided with the stud k>olts 51, 72 (not shown in Figures 9 and 10) required to support the rail support elements and the LIM reaction rail support elements (if the railway is of the LIM type). The jig may be aligned with and positioned against the inside upper form 112 so that these stud bolts 51, 72 project into the interior space that will be filled by the concrete. The stud bolts 51, 72 can be temporarily retained in place using a pair of nuts, one on the interior surface of the forming wall and the other on the exterior surface of the forming wall. When the concrete has set, the nuts on the exterior portions of the forming wall can be removed, leaving the stud bolts 51, 72 projecting. The forms can then be simply pulled away 'from the set concrete, leaving the stud bolts 51, 72 projecting from the concrete surfiaces in the places where they are to be located. In order to permit the forms to be readily removed from the parapets 42, the parapets 42 should be formed with inclined surfaces flaring outwardly from top to bottom as perceived in Figure 4. It is usually preferred, again so that the forms may be readily removed from the parapet portions of the structure, to use inset female elements on one parapet for supporting the electric power delivery rails (as illustrated in Figure 4).
Positioned on either side of the rectangular truss; 128 are form support ramps that support the form structures 110. Atop the ramps 130 in the vicinity of their outermost edges are hinges 138 each including a generally elongate trough or angled form support bracket 139 pivotal with the hinges 138. On each support bracket 139 rests the lowermost edge 160 of a respective bottom form 114 when the assembled form structure 110 is positioned atop the associated ramp 130. The concrete is poured into the form cavity 116 and the concrete permitted to set. When the concrete has set, each form 110 is tilted and pivoted away from the rectangular truss 128 so as to lie almost flat on the ground (or platform, or as the case may be). The upper form 112 is. provided with apertured tabs 162 to which grappling hooks (not shown) may be attached for separating and removing the top form 112 from the bottom form 114, once the bolts securing the two forms 112, 114 together have been removed.
The track guideway arrangement and deck slab design illustrated in Figure 11 are relatively simple and suitable for an elevated railway in which power is supplied via an overhead catenary system. The illustration of Figure 11 is schematic only and omits a number of components that would be found in such arrangements, including especially the connectors for connecting the deck slabs 118 to the girder 12. Most of the discussion of Figure 4 is applicable to Figure 11; the main differences are differences of detail by reason of the simpler upper surface structure of the deck slab 118 of Figure 11 because of the absence of an LIM reaction rail and associated LIM-related elements or support structure. (Note, however, that power rails could be mounted on the parapets 142 for use with conventional electric railways in which the power is supplied on such power rails just above ground level and returned via the train wheels 1:o the carriage support rails 152, which would also serve as return conductors for the elE:ctric circuit.) The particular deck slab 118 illustrated in Figure 11 is provided with slightly elevated integrally formed rail plinths 148 provided with female threaded receptacles 150.
The upper surfaces 158 of the rail plinths 148 are preferably slightly inwardly canted (typically with a 1:20 cant) to avoid "hunting" of the railway carriage wheels on the rails, in accordance with conventional design. The arrangement illustrated in Figure 11, like that of Figure 4, permits the rail support elements 154 to be~ of rectangular cross-section, and therefore less costly to manufacture. The structure of Figure 11 differs from that of Figure 4 in that the elevated concrete plinths 148 serve not only to present an upper canted surface for attachment to and support of the rail support elements 154, but also provide derail abutments against which the wheels of a derailed train may bear so as to constrain sideways motion of a derailed train; the parapets 142 serve as further protection against derailment, and provide sound abatement.
For the combined structure of Figure 11, girders 12 and slabs 118 can be of generally the same length as counterpart elements prEwiously described with reference to Figure 4, and can be connected together and groutE:d in essentially the same way as discussed previously with reference to Figures 4 and 5.
Variants and alternatives other than those described in the above specification will occur to a person skilled in the art, and do not depart from the spirit of the present invention. For example, an alternative to the U-shaped .girder element 12 used to support the guideway track slabs 18 in the case where the guideway passes through a tunnel, such as a continuous foundation slab, is described above, although it is understood that further such support variants, possibly including for example steel truss girders, may be employed, all of which variants fall within the scope of the present invention. In a further example, variants of the particular fittings and attachments described in the above specification such as stud bolts 51, 72, and rail support elements 55 may be alternatively employed; structures including such alternative components also fall within the scope of the present invention. It is understood that the particular embodiments of the present inventive railway support structure and associated method and apparatus for producing said support structure described in the present specification are exemplary in nature, and do not limit the scope of the present invention. The :.cope of the present invention is defined in the following claims.

Claims (30)

1. A guideway member in or for use in a support structure of an elevated railway, said guideway member comprising a deck slab having an upper surface and a lower surface, the upper surface of the deck slab comprising (i) a central portion;
(ii) two lateral portions for fixedly supporting rails; and (iii) two longitudinally extending parapets spaced from one another, each of said parapets being fixedly positioned in the vicinity of the outer longitudinal edge of an associated lateral portion of the upper surface of the deck slab and extending substantially perpendicularly to the deck slab, characterised in that the lateral portions of the upper surface of the deck slab are inwardly canted relative to the lateral axis of the slab, for stabilizing the wheels of a vehicle travelling along the railway.

2. The guideway member of claim 1, wherein the central portion of the upper surface of the deck slab is elevated relative to the lateral portions.

3. The guideway member of claim 2, further comprising a transitional zone having a substantial slope between the elevated central portion and each of the lateral portions on the upper surface of the deck slab, for maintaining the positioning of wheels of a rail vehicle within each lateral portion in the event of a derailment.

4. The guideway member of claim 3, wherein said transitional zone comprises a substantially perpendicular shoulder for maintaining the positioning of wheels of a rail vehicle within each lateral portion in the event of a derailment.

5. The guideway member of any of claims 2-4, wherein said elevated central portion fixedly supports a reaction rail for communicating with linear induction motor means of a rail vehicle.

6. The guideway member of claim 5, wherein said reaction rail is fixed to said elevated central portion with male stud bolt means.

7. The guideway member of any of the preceding claims, wherein each parapet is integral with the deck slab.

8. The guideway member of claim 7, wherein each said parapet comprises inner and outer side walls of substantial slope convergently extending upwardly from the deck slab.

9. The guideway member of any of the preceding claims, wherein each said canted lateral portion is provided with connection element, for fixedly connecting at least one rail support element.

10. The guideway member of claim 8, wherein the rail support element has substantially the form of a rectangular parallelepiped.

11. The guideway member of any of the preceding claims, wherein each said canted lateral portion fixedly supports a parallelepiped rail support element.

12. The guideway member of claim 10, wherein the parallelepiped rail support element is fixed to the associated canted lateral portion by means of male stud bolt means embedded in said lateral portion.

13. A girder member in or for use in a support structure of or for an elevated railway, said girder member comprising an open elongate generally U-shaped structure having two spaced upwardly extending webs, the uppermost flanges of said webs provided with fasteners for connection to a series of longitudinally arrayed deck slab members and a lowermost flange integral with and extending between said webs, the underside of said lowermost flange being provided with means for supporting the girder member.

14. The girder member of claim 12 in or for use with a horizontally-curved portion of said support structure, wherein the deck slab support flange of the upwardly extending web in the vicinity of an outer edge of said curved portion is higher than the deck slab support flange of the upwardly extending web remote from said outer edge, in order to apply additional inwardly directed force to a vehicle travelling along said horizontal curvature, and to reduce the risk that said vehicle will tip over.

15. A support structure for an elevated railway, said support structure comprising:
(a) a series of guideway deck slab members according to any of claims 1 to 11, and (b) at least one girder member according to claim 12 or 13; and wherein a series of deck slab members is fixedly positioned on one or more girder members, the upper ends of the upwardly extending webs of such girder members engaging the lower surface of each deck slab and supporting such slab in the vicinity of the longitudinal edges of such slab;
wherein the guideway members and the girder members are separately formed and subsequently assembled into the support structure.

16. The support structure of claim 15, wherein the upper surfaces of the upwardly extending webs of the girder are grouted to the guideway deck slabs with concrete or grout to form an integral support structure for an elevated railway.

17. A concrete forming apparatus for casting a structural slab having selected surface characteristics, comprising:
(a) a forming mold for molding the slab therein, being comprised of at least two mutually detachable forming elements for coupling together to form a container into which concrete can be poured and for disengagement after the concrete has set to permit the cast concrete slab to be released from the mold, the mold having its inner surface configured to correspond to the selected outer surface characteristics of the slab;
(b) a mold support for supporting the mold in either of two positions, viz a casting position and a release position;

(c) release facilitation means for facilitating the release of the set slab from the mold after the concrete slab has set and the mold is in release position;
the forming mold being provided with a pouring portal for pouring fluid concrete into the forming mold, said pouring portal being uppermost when the mold is in casting position.

18. A concrete forming apparatus as defined in claim 17, wherein the mold support comprises a base for resting on a substantially horizontal surface; and a mold support hinge pivotally mounted on the base for pivoting about a substantially horizontal pivot axis and for supporting the mold and for pivoting the mold between the casting position and the release position of the mold.

19. A concrete forming apparatus as defined in claim 18, wherein the mold support additionally comprises a resting support for the mold in casting position, the resting support extending generally parallel to the mold support hinge pivot axis and being located over center relative to the mold in release position, so that in moving from release position to casting position, the mold orientation changes through a pivotal angle of slightly more than a right angle from approximately horizontal to a slight inclination to the vertical.

20. A concrete forming apparatus as defined in claim 19, additionally comprising a frame in the form of a pair of parallel end trusses between which is fixed a central mold support truss, and comprising a pair of mold supports each as defined in claim 3 on either side of the mold support truss, the pivot axes for the two mold supports being parallel to one another and to the plane of the central mold support truss, the hinge for each said mold support being fixed to its associated said base at a spacing from the central mold support truss sufficient to permit the edge of the mold nearest the central mold support truss to rest against the central mold support truss when the mold is in casting position, the frame on one side of the central mold support truss being substantially the mirror image of the frame on the other side of the central mold support truss, thereby permitting a pair of said slabs to be cast concurrently and the inwardly directed forces applied to the central mold support truss by the molds filled with concrete to be balanced.

21. A concrete forming apparatus as defined in claim 19, wherein the base for each said mold support has a generally horizontal undersurface and an upper generally flat surface downwardly inwardly inclined toward the central mold support truss at an angle to the horizontal that substantially matches the over-centre angle to the vertical assumed by the mold when in casting position.

22. A concrete forming apparatus as defined in claim 21, wherein the ends of the base for each said mold support are respectively mixed to the adjacent end truss.

23. A concrete forming apparatus as defined in claim 22, wherein the uppermost forming element when the mold is in release position covers the entire upper surface of the cast concrete slab, so that when uncoupled from the forming element or elements thereunder, upward movement thereof frees the upper portion of cast slab; and wherein the release facilitation means comprises a spaced array of protrusions fixed to and extending generally outward from said uppermost forming element.

24. A concrete forming apparatus as defined in claim 23, wherein the mold comprises two said forming elements, and wherein the uppermost forming element when the mold is in release position covers the entire side surfaces of the cast concrete slab, so that when the uppermost forming element is moved upward away from contact with the cast concrete slab, the slab remains supported on the lowermost forming element acting as a support for the slab.

25. A concrete forming apparatus as defined in claim 24, wherein each of the protrusions has an eye for engagement by a grapple.

26. A concrete forming apparatus as defined in claim 24, wherein each of the protrusions is a hook for engagement by a grapple.

27. A concrete forming apparatus as defined in claim 24, wherein the lowermost forming element approximates the general overall shape of a rectangular parallelepiped and when in release position ha s a generally horizontal upper surface on which the slab rests.

28. A concrete forming apparatus as defined in claim 24, wherein the uppermost forming element when the mold is in release position further comprises an array of holes for placing stud bolts partially into the interior of the mold prior to the pouring of concrete so that the stud bolts are embedded in the cast slab.

29. A concrete forming apparatus as defined in claim 28, wherein each said stud bolt is secured by two threaded fasteners one on each side of the uppermost forming element so that the mold can be removed by removing the outside threaded fastener after the concrete slab is set, leaving the stud bolt embedded therein with a pre-selected extension from the surface of the slab.

30. A method for casting a structural slab having selected surface characteristics using a two-component forming mold whose mold cavity conforms to the dimensions and configuration of the slab to be cast, the mold having two stable positions, viz a casting position and a release position, the release position being generally horizontal and the casting position being generally vertical or at a slight angle to the vertical; comprising the steps of (a) pivoting the forming mold from the horizontal position over-centre into the casting position, (b) pouring fluid concrete into the mold, (c) holding the mold in the casting position until the concrete has set, (d) pivoting the mold through vertical dead-centre and thence through about a right angle to the release position, (e) removing one component of the two-component mold to expose the slab, leaving the slab resting on the remaining component of the mold, and (f) releasing the slab from the remaining component of the mold.