EP0434555A1 - Viaduct for a railway track - Google Patents

Abstract

Essentially metal viaduct for a railway track for a vehicle rolling on two rails. According to the invention, the deck held above the ground, for example by piers, is noteworthy in that the rails (14) form an integral part of the said deck by being, for example, integrated with portions of perforated metallic structure comprising tie-rods (20), sleepers (26) and elements forming a crosspiece (sleeper) (22) defining a triangulated network. <IMAGE>

Description

The invention relates to a viaduct for a railway track allowing the air traffic of vehicles traveling on two rails; it relates more particularly to a new architecture of such a viaduct, which fits particularly well in an urban site.

Until now, rail transport has mainly developed with heavy vehicle trains. As far as urban journeys are concerned, this type of transport has mainly developed on the ground (trams) and underground (metropolitan). The sections of overhead metro built so far have a very massive infrastructure which does not generally integrate happily into the urban landscape. The operation of these overhead lines is often noisy and poorly supported by local residents.

In recent years, rail transport systems have appeared using vehicles of smaller capacity, more flexible use and low noise. These high-performance systems can help change the appearance of public transport in cities, but it appears that, for economic reasons, their development is directly linked to operation on air infrastructure. However, up to now, the achievements of this type call upon a viaduct of classic design and consequently of massive general aspect integrating with difficulty in the urban landscape. In addition, the cost price of such a viaduct is high, and can represent more than half of the total cost of a new transmission line. More specifically, in such a viaduct of conventional design, the rails rest on an apron comprising an assembly of crosspieces and beams and the apron is itself carried by pillars. The deck must be designed to support the weight of the track and vehicles.

The invention mainly proposes a new deck structure making it possible to considerably reduce the mass of the entire viaduct.

More specifically, the invention therefore relates to a viaduct for a railway track, for a vehicle traveling on two rails or similar rolling means, comprising an apron held above the ground by pillars or similar structures, characterized in that said rails are an integral part of said deck and in that at least a part of the latter consists of sections of perforated metal structure.

“Perforated metal structure” is understood to mean a structure composed of a rod or tie rod assembly mainly comprising rails, sleepers and other similar structural elements which are profiles of small cross section relative to their length. It goes without saying, however, that the definition of "openwork" metal structure only relates to the load-bearing framework and that a viaduct thus designed but "clad" with decorative elements causing it to lose its openwork appearance, would nevertheless fall within the scope of protection. defined above.

It is thus possible to envisage a viaduct, the deck of which is essentially produced by assembling metallic elements directly linked to the rails. Thus, the rails are no longer only intended to locally support the weight of the trains and to guide them, but they also constitute important elements of the deck itself, connected to the rest of the infrastructure to absorb certain constraints and in particular stresses. longitudinal compression generated by the passage of a vehicle or train of vehicles. Indeed, in a metal deck structure, the elements which work in compression (and which therefore risk being damaged by buckling) must have much larger sections than those which work essentially in tension. Now, the normal section of a rail may be sufficient to adequately withstand the longitudinal compression forces which arise from the passage of a train. In other words, a remarkable characteristic of the invention consists in arranging the deck so that the longitudinal compression forces defined above are essentially supported by the rails themselves. In this way, the rest of the infrastructure can be made up of elements of relatively small section and particularly those which only work in traction. These can then be simple tie rods or cables a few centimeters in diameter. As a result, the entire deck is considerably reduced since it essentially consists of the assembly of rails, sleepers and tie rods or cables. It therefore acquires a sort of "transparency" which greatly facilitates its integration into an urban landscape at a much lower cost than that of a conventional solution.

There are essentially two kinds of viaducts meeting the definition of the invention set out above: "subtended" viaducts in which the rails are mounted at the top of a truss beam and where the lower elements of this beams are mainly constituted by tie rods arranged to work in traction and "suspended" viaducts where the rails are carried by sleepers, the latter being themselves attached by cables or tie rods to upper anchor points, for example belonging to the pillars.

• la figure 1 est une vue schématique en élévation d'une partie de viaduc conforme à l'invention;
• la figure 2 est une vue en perspective d'un tronçon autoporteur du tablier de ce viaduc;
• les figures 3 à 6 sont des vues de détails de l'assemblage de différents éléments du tronçon de tablier de la figure 2;
• la figure 7 est une vue schématique en élévation d'une partie d'un autre type de viaduc conforme à l'invention; et
• la figure 8 est une vue de dessus du viaduc de la figure 7.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of several embodiments of viaducts in accordance with its principle, given solely by way of example and made with reference to the accompanying drawings in which:

• Figure 1 is a schematic elevational view of a viaduct part according to the invention;
• Figure 2 is a perspective view of a self-supporting section of the deck of this viaduct;
• Figures 3 to 6 are detailed views of the assembly of different elements of the deck section of Figure 2;
• Figure 7 is a schematic elevational view of part of another type of viaduct according to the invention; and
• FIG. 8 is a top view of the viaduct of FIG. 7.

Referring more particularly to Figures 1 and 2, there is shown a viaduct 11 carrying two railway tracks 12, 13 with two rails each. Therefore, the viaduct comprises four rails 14, parallel. It consists of metal sections 16 defining an openwork lattice structure, carried between pillars 18 or similar supports. In the example, each section forms a sort of individualized beam which can be prefabricated and whose ends rest on pillars. It is conceivable to weld the rails end-to-end once the sections have been laid, leaving the necessary expansion spaces at suitable locations, especially when the sections are arranged in a straight line. One can also consider an on-site construction of the different sections, in which case the rails may be longer than the distance between the pillars. All of the metal sections 16 form the apron of the viaduct and, in accordance with the principle of the invention, the rails 14 form an integral part of this apron. Each metal section 16 here forms a sort of self-supporting metal lattice beam, and the rails occupy the upper part of this beam. They are therefore naturally placed to withstand most of the longitudinal compression forces generated in the beam when the vehicles pass. These rails thus integrated into the deck are subtended by tie rods 20 constituting, in association with cross-member elements 22, here triangular and cross-members 26 (at the ends of each section), a triangular network, entirely metallic, by which the rails are subtended. More precisely, each triangular element forming a crosspiece 22 is mounted vertically under the rails. It comprises an upper horizontal segment 22 a , constituting the actual cross member and extending perpendicular to the rails and two inclined lateral segments 22 b , forming a V. The rails are fixed to the upper horizontal segment 22 a . When passing a vehicle, the segment 22 a essentially undergoes bending stresses while the segments 22 b undergo compression stresses. They are therefore sized to withstand these types of forces, that is to say in particular to avoid buckling. The sleepers 26, the ends of each segment 16 are substantially identical to segments 22a and are fixed to the rails in the same way. The elements 22 and the crosspieces 26 are regularly spaced from each other. The tie rods 20 are, in turn, of appreciably smaller section because they are mounted so as to be practically only subjected to tensile forces. According to the nonlimiting example shown, the triangulation is achieved by mounting such a tie between the lower end 25 of each element 22 and the ends of the crosspieces 26 and / or of the neighboring elements 22. In this way, said beam is only made up of rigid and non-deformable triangular meshes. As mentioned above, at least some of the tie rods can be replaced by cables.

Figures 3 to 6 show several possible arrangements for assembling elements 22 and the various tie rods 20 which are attached thereto. In FIGS. 3 to 5, the assembly is suitable for the lower end 25 a of an element 22 situated between two other elements 22. Such an assembly may include, for example, plates 28 fixed in the vicinity of said lower end 25 a and the ends of the corresponding tie rods 20 are fixed, preferably welded, to said plates. In the examples of FIGS. 3 and 5, the segments 22b of the element 22 have a square section and the plates 28 are advantageously welded to the outer faces of these segments, near the end 25 a . For the assembly of a tie rod and the plate, one can make a longitudinal slot at the end of the tie rod, engage this split end on the plate and weld. On the contrary, you can make the slot in the plate, place the end of the tie rod in it and weld. We can also mount a kind of connecting piece 32, here in the form of a yoke, at the end of the tie rod (see Figure 5) engage it on the plate and fix it in this position, either by bolting or by welding . The end of the tie rod 20 can advantageously be provided with a threaded part 33 while the connection piece 32 has a tapped hole. The connecting piece 32 thus forms a kind of nut and this assembly makes it possible to adjust the useful length of the tie rod on the spot.

Regarding the mounting of the tie rods connected to the lower end 25 a of an element 22 located between two other elements 22, there are two lower horizontal tie rods (marked 20 a , 20 b in the drawings) which connect the lower ends of these three elements 22. As shown in FIGS. 3 to 5, these aligned horizontal tie rods can be in one piece, the cylindrical metal bar defining all of said tie rods being fixed, for example welded to the lower ends of the elements 22. Good understood, the same arrangement can be applied for any number of lower horizontal tie rods connecting more than three successive elements 22.

In FIG. 4, the mounting of the inclined tie rods 20 no longer uses a plate 28. Thus, the two inclined tie rods 20 respectively connecting the same lower end of a cross member to an upper end (at the level of the track) of a neighboring element 22 or at one end of a neighboring cross-member 26, are in one piece forming a bend 34 in the vicinity of said lower end. A fixing, such as preferably a weld, is made between these two tie rods 20 and the element 22, at said bend. To do this, a support piece 35 is fixed, preferably welded, to the external side wall of each segment 22 b . This part advantageously includes a curved edge corresponding to the curvature of the metal bar constituting the tie rods. The latter is bent at the support piece and welded against said curved edge. The same assembly is of course possible as regards the lower end of an element 22 situated between a similar element 22 and an end crosspiece 26.

Similarly, it is clear that the same assembly can be applied for the tie rods joining the same upper end of an element 22. In other words, two inclined tie rods respectively connecting the same upper end of an element 22 to a lower end of a neighboring element 22 may be in one piece forming an elbow in the vicinity of said upper end, that is to say at the level of the track. The fixing is preferably carried out by welding at the elbow of the metal bar, advantageously against the curved edge of a support piece similar to the piece 35. Using the same mounting successively at the lower and upper ends of the elements forming crosspieces , all of the inclined tie rods of the same section forming the beam can be produced from only four metal bars of suitable length, regardless of the number of elements 22 forming part of the beam.

FIG. 6 represents yet another type of connection of the tie rods inclined at an upper end (situated at the level of the track) of an element 22. This fixing uses plates 38 playing the same role as the plates 28, it that is to say ensuring the welded fixing of the end of a corresponding inclined tie rod. Each plate 38 is fixed, preferably welded, to a segment 22b on a face thereof perpendicular to the railroad track. The plate 38 is also preferably welded under the neighboring external rail 14. The exact position of the plate relative to segment 22 b may vary transversely of a few centimeters, from one element 22 to another, to allow crossing without constraint and preferably without contact of the inclined tie rods 20.

For the production of curved metal sections 16, it suffices to provide curved rails 14, with the chosen curvature and tie rods 20 of different lengths and adapted on either side of said section.

Figures 7 and 8 show a variant of the application of the principle of the invention to a viaduct structure where the rails 14 are suspended. In this embodiment, the deck is essentially constituted by the rails 14 themselves and sleepers 40 regularly spaced along the track and fixed to said rails. The sleepers are themselves connected, at their ends, to tie rods 42, cables or the like, connected to anchor points 43 above the deck. In the example shown, these anchor points 43 are formed by the tops of the pillars 45 or similar structures. Each pillar is here constituted by two pairs of inclined uprights extending on either side of the track and meeting to define the upper anchor points. As in the previous embodiment, the rails 14 integrated into the structure of the deck, are mounted to absorb the longitudinal compression forces due to the passage of vehicles while the tie rods 42 work in traction.

Of course, many variants and adaptations are possible. For the lattice beams described above, the arrangement of the profiles can be such that they do not work exclusively in traction. You can also combine "subtended" sections and "suspended" sections alternating along the line. It can also be envisaged that subtended sections are integrated into a suspended structure, which is advantageous for long spans between pillars with a reduced number of tie rods or cables mounted according to the configuration in FIG. 7. Finally, the deck can advantageously include a longitudinal gangway for maintenance and possibly passenger evacuation. For an apron carrying two traffic lanes, this walkway may advantageously be in the center, between the two lanes.

Claims (13)

Viaduct for a railway track, for a vehicle running on two rails or similar rolling means, comprising an apron held above the ground by pillars (18, 45) or similar structures, characterized in that said rails (14) form an integral part of said apron and in that at least a part of the latter consists of sections of perforated metal structure. Viaduct according to claim 1, characterized in that elements of said deck adapted and dimensioned to support the longitudinal compression forces generated by the passage of a vehicle are constituted by the rails (14) mentioned above themselves. Viaduct according to claim 1 or 2, characterized in that such a section forms a beam whose said rails (14) occupy the upper part and are subtended by tie rods (20) and / or cables of a triangulated network. Viaduct according to claim 3, characterized in that said section comprises at least one cross member (22), preferably triangular, fixed vertically under the rails, in that the lower end of this element is connected to the ends of cross members ( 26) and / or adjacent cross-member elements (22) by tie rods (20) or cables working essentially in traction. Viaduct according to claim 4, characterized in that such a cross member is provided with at least one plate (28, 38) fixed in the vicinity of one of its ends and in that at least one end of such a tie rod (20) is fixed to said plate. Viaduct according to claim 4 or 5, characterized in that two inclined tie rods respectively connecting the same lower end of a cross member (22) to an upper end of a neighboring member (22) or to one end of a cross (26) adjacent, are in one piece forming an elbow (34) in the vicinity of said lower end, a fixing, preferably a welding, being carried out between these tie rods and the element, at the level of said elbow. Viaduct according to one of claims 4 to 6, characterized in that at least two inclined tie rods respectively connecting the same upper end of a cross member to a lower end of a neighboring cross member are in one piece forming a bend in the vicinity of said upper end, a fixing, preferably a weld, being produced between these tie rods and said cross member, at said bend. Viaduct according to one of claims 4 to 7, characterized in that lower horizontal tie rods (20 a , 20 b ) connecting the ends of at least three neighboring cross-member elements (22) are in one piece. Viaduct according to one of claims 4 to 8, characterized in that at least some of the tie rods have a threaded end (33) on which is screwed a connection piece (32) forming a nut, itself fixed to the element forming cross or to the corresponding cross. Viaduct according to one of the preceding claims, characterized in that at least part of said deck is simply constituted by the rails (14) and crosspieces (40) fixed to said rails and in that said crosspieces are themselves connected by their ends to tie rods (42), cables or the like connected to anchor points (43) above said deck, on said pillars or similar structures. Viaduct according to one of the preceding claims, characterized in that at least part of said deck consists of sections of aforesaid perforated metal structure connected to tie rods, cables or the like connected to anchor points higher than said deck. Viaduct according to one of the preceding claims, characterized in that said deck comprises a longitudinal walkway. Viaduct according to claim 12 comprising two parallel tracks, characterized in that said footbridge extends between the two tracks.

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