Level Railway Crossing The invention relates to a level railway crossing extending over one or more tracks. 5 Level railway crossings that extend over one or more tracks may comprise transverse sleepers for mounting the rails of the respective track, whereby the railway crossing includes a traffic surface which can be driven over and which is formed by cover elements, wherein said cover elements at their rims 10 facing the rails rest only on the respective rails, and cover elements arranged between two rails of a respective track self supportingly bridge the space present between these rails from rail to rail, and wherein cover elements are provided to outwardly adjoin the rails of the respective track or of the 15 respective tracks, which on their rail-side rim rest on the respective rail, and at their side which faces away from this rail rest on bases. By the special design of the support of the cover elements it is achieved in railway crossings of the aforementioned type 20 that the cover slabs do not have a direct influence on the carrying structure of the rails, whereby a detrimental influence by the coverage on the elastic behaviour of the tracks is largely avoided. Thus, in particular, a detrimental influence on a sub-structure of ballast serving as an elastic 25 track foundation is averted, and in this way it is also avoided that in the region of such railway crossings, the tracks will have elastic properties different from those prevailing at track portions located externally of the railway crossings. During braking and accelerating operations as well as 30 during steering movements, road vehicles exert great forces on the cover elements over which they drive in the region of railway crossings, which forces, in combination with the loads exerted by the road vehicles and in combination with the dead weight of the cover elements, are transmitted to the rails of 35 the tracks. By this, the rails are subjected to a substantial 2558052_1 (GHMatters) - 2 bending stress in both, vertical and horizontal directions. Forces acting horizontally and transversely to the rail direction seek to shift the track horizontally, yet these forces being counteracted by the frictional forces between 5 sleepers and substructure, on the one hand, and by the bending stress of the rails, on the other hand. In a first aspect there is provided a level railway crossing extending over one or more tracks, which tracks comprise transverse sleepers for mounting the rails of the 10 respective track, which railway crossing includes a traffic surface which can be driven over and which is formed by cover elements, wherein said cover elements at their rims facing the rails rest only on the respective rails, and cover elements arranged between two rails of a respective track self 15 supportingly bridge the space present between these rails from rail to rail, and wherein cover elements are provided to outwardly adjoin the rails of the respective track or of the respective tracks, which cover elements, on their rail-side rim, rest on the respective rail and, at their side which faces 20 away from this rail, rest on bases, wherein the rails of the track, or tracks, respectively, on which the cover elements provided in the region of the railway crossing rest via their rims facing the rails, in the region of said railway crossing are mounted on and fastened to supporting beams which extend 25 along the rails underneath the latter, wherein the supporting beams associated to the two rails of the respective track are interconnected by transverse webs, and the supporting beams in turn rest on a substructure, and the rails only externally of the region of the railway crossing are mounted on said 30 transverse sleepers. An advantage of an embodiment of the level railway crossing is to provide a crossing of simple construction and which can be constructed at many locations without any problems, and in which a good stability of the position of the track and a 2558052_1 (GHMatters) -3 bending stress of the rails as slight as possible can be achieved. The supporting beams on which the rails are mounted are capable of accommodating a substantial portion of the bending 5 loads caused by the forces that are transferred to the rails by the cover elements, and by said supporting beams these forces are transmitted to the substructure distributed over a comparatively long portion of the track, which, in combination with the stiffness inherent in the supporting beams, results in 10 a very good stability of the position of the track. Substantial importance is also to be attributed to the combination effect resulting from the fact that the cover elements which each self-supportingly bridge regions of the track rest on the rails, and from the fact that the rails are mounted on and 15 fastened to the longitudinally extending supporting beams which, in turn, rest on a substructure. After a removal of the cover elements, there is also a good access to the substructure, on which the supporting beams rest so that maintenance work on this substructure can be carried out in a 20 simple manner. By connecting the supporting beams, associated with the two rails of a track, by means of transverse webs, the construction work carried out when providing a railway crossing is facilitated, and the stability of the gauge of the track in the region of the railway crossing is ensured in a simple 25 manner; furthermore, these transverse webs also have the effect that a large portion of the forces transmitted from the cover elements to the track are always transmitted by both supporting beams to the substructure, even if a substantial portion of the force transmission changes from one rail of the track to the 30 other rail of the track when a railway crossing is passed over by vehicles; this equalization of the force transmission to the substructure effected by the transverse webs assists in stabilizing the position of the track in the region of the railway crossing. 2558052 1 (GHMatters) - 4 Preferably, it is provided for the supporting beams in turn to be mounted on a substructure of ballast. This design is favourable for an adaptation of the elastic behaviour of the track in the region of the railway crossing to the elastic 5 behaviour of the track path assembled with transverse sleepers. In this connection, it may be mentioned that the elastic behaviour of a track has a substantial influence on the dynamic driving properties of vehicles. Also other designs of the substructure may be provided, e.g. by the supporting beams 10 resting on a subgrade, wherein this subgrade may also be levelled out by a thin layer of gravel or the like. Furthermore, an advantageous embodiment of the railway crossing designed according to the invention results if the supporting beams are provided with a pressure-deformable layer on their 15 bottom side. By this, a good, solid seating of the supporting beams on the substructure is achieved, wherein tolerances of the substructure can be levelled out, and also the resistance against shifting of the supporting beams relative to the substructure is improved. A suitable further development of 20 this embodiment is that the pressure-deformable layer with which the supporting beams are provided at their bottom side, is a pressure-elastic layer. By this, the seat of the supporting beams on the substructure is further improved, and also damping of the impact sound is achieved which is caused by 25 vehicles passing over the area of the railway crossing, and the pressure-elastic layer also allows for an automatic levelling out of irregular settlings in the substructure. One advantageous embodiment in this respect is that the pressure elastic layer is formed of an elastomer. 30 An advantageous embodiment of the railway crossing, the supporting beams are provided with a pressure-deformable layer at their bottom side, wherein the pressure-deformable layer is foamed. In this manner, on the bottom side of the supporting beams a pressure-deformable layer can be formed with 35 comparatively little material expenditure, which layer adapts 2558052_1 (GHMatters) - 5 snugly to the substructure, has good equalizing properties with regard to substructure tolerances, and good damping properties with regard to impact sound. It is furthermore advantageous if it is provided that the 5 supporting beams, viewed in the rail longitudinal direction, extend to beyond the rims of the traffic surface that extend transversely to the rail longitudinal direction. Thus, with regard to the track properties, particularly with regard to the dynamic properties of the track, a smooth connection to the 10 track path located externally of the railway crossing can be achieved very easily. It is furthermore suitable if it is provided for the supporting beams arranged underneath the individual rails of the respective track to be formed by several supporting beam 15 parts which are consecutively arranged in the rail longitudinal direction and interconnected. This has advantages with regard to the transportation of the supporting beams provided for a railway crossing and with regard to the handling of these supporting beams when constructing the railway crossing, and 20 furthermore, it is advantageous that the connection of the consecutively arranged and interconnected supporting beam parts protects the rails from stress at the sites of transition of a respective one supporting beam part to the consecutive supporting beam part, which stress could result from a movement 25 of the supporting beam parts relative to each other. The invention will be explained hereinafter in more detail with reference to exemplary embodiments which are schematically illustrated in the drawings. In the drawings, Fig. 1 shows a top view onto a track with a part of a 30 railway crossing which traverses this track, and which constitutes an exemplary embodiment; Fig. 2 shows this embodiment of a railway crossing in a section according to line II-II of Fig. 1; 2558052_1 (GHMatters) -6 Figs. 3 and 4 show modified embodiments of a railway crossing, in sectional representations corresponding to Fig. 2; and Fig. 5 shows a top view of an embodiment of a railway 5 crossing, which is modified with regard to the supporting beams and extends over two tracks. The railway crossing 1 illustrated in Figs. 1 and 2 leads across a track 2 and has a traffic surface 4 formed of cover elements 6, 7. On both sides of the track, the traffic surface 10 4 is followed by road surfaces 5. The cover elements 6 are arranged between the rails 10, 11 of the track 2, and the cover elements 7 are arranged to adjoin the rails 10, 11 of the track outwardly. The cover elements 6, 7 rest at their rims 8, 9 which face the rails 10, 11, only on the rails 10, 11 of the 15 track 2 with elastomer sections 8a, 9a interposed. The cover elements 6 arranged between the rails 10, 11 of the track 2 self-supportingly bridge the space 12 present between the rails 10, 11 from rail to rail; the cover elements 7 outwardly adjoining the rails 10, 11 each rest on the respective rails 20 10, 11 with their rail-side rim 9 via interposed elastomer sections 9a, and with their side 13 that faces away from the respective rail they rest on bases 14. In the region of the railway crossing 1, the rails 10, 11 of the track 2 are mounted on supporting beams 15, 16 arranged 25 underneath the rails 10, 11 so as to extend along said rails 10, 11. The rails 10, 11 are connected to the supporting beams 15, 16 by means of rail fastening elements 17. The supporting beams 15, 16 associated to the two rails 10, 11 of the track are interconnected by transverse webs 18, and the supporting 30 beams 15, 16 in turn rest on a substructure formed of ballast 19 in this exemplary embodiment. Externally of the region of the railway crossing 1, the rails 10, 11 of the track 2 are mounted on transverse sleepers 20 which in turn are laid on a substructure of ballast 21. 25580521 (GHMatters) - 7 The supporting beams 15, 16 may end at the lateral rims 22 of the traffic surface 4. Yet, to provide for an improved load distribution, and to provide for uniformity of the dynamic properties of the track in the region of the railway crossing 5 1, on the one hand, and in the region of the track paths following said railway crossing 1, on the other hand, it is suitable if, viewed in the rail longitudinal direction 23, the supporting beams 15, 16, as is illustrated in Fig. 1, extend to beyond the lateral rims 22 of the traffic surface 4, which 10 lateral rims 22 extend transversely to the rail longitudinal direction. In the embodiment illustrated in Fig. 3, the supporting beams 15, 16 that extend underneath the rails 10, 11 are mounted on a subgrade 24 whose upper side is levelled out and 15 stabilized by a gravel layer 25. In the embodiment illustrated in Fig. 4, the supporting beams 15, 16 arranged underneath the rails 10, 11 are provided with a pressure-deformable layer 27 on their bottom side 26, which layer 27 rests on the substructure realized in the form 20 of a substructure of ballast 19. Due to the deformability of the layer 27, this layer snugly adapts to the irregular upper side of the substructure of ballast 19, and in this manner a particularly good adherence of the supporting beams 15, 16 on the substructure of ballast 19 is achieved, which prevents an 25 undesired lateral shifting of the supporting beams 15, 16, and also an equalization of shape tolerances of the upper side of the substructure of ballast 19 is achieved. The pressure deformable layer 27 may, e.g., have a thickness of one or more centimeters. In most cases it is advantageous if the pressure 30 deformable layer 27 is a pressure-elastic layer, it being suitable to form such a pressure-elastic layer by an elastomer. In the interest of little material expenditures and in the interest of little construction efforts, it is suitable for the pressure-deformable layer 27 to be a foamed layer, such an 35 embodiment also being suitable for obtaining a good adherence 25580521 (GHMatters) - 8 of the supporting beams 15, 16 on the substructure, or on a ballast 19, respectively, and also for achieving good damping of impact sound which forms when the railway crossing is driven on. 5 The railway crossing illustrated in Fig. 5 leads across two tracks 2, 3 extending side by side. The traffic surface 4 of this railway crossing 1 is formed by cover elements 6, 7, with the cover elements 6 arranged between the rails 10, 11 of track 2 and between the rails 10, 11 of track 3 resting only on these 10 rails 10, 11, self-supportingly bridging from rail to rail the space present between the rails 10, 11 in each one of these tracks. The cover elements 7 are arranged to outwardly adjoin the rails of the tracks 2, 3, and with their rims 9 that face the rails 10, 11, they rest on these rails 10, 11, and with 15 their side 13 facing away from the respective rail 10, 11, they rest on bases 14. Externally of the region of the railway crossing 1, the rails 10, 11 of the tracks 2, 3 are mounted on transverse sleepers 20 which in turn rest on a substructure of ballast 21. The supporting beams which, in the region of the 20 railway crossing 1, are arranged underneath the individual rails 10, 11, are formed by several supporting beam parts 15a, 15b, 16a, 16b consecutively arranged in the rail longitudinal direction 23 and interconnected. The connection of the supporting beam parts 15a, 15b, on the one hand, and 16a, 16b, 25 on the other hand, is effected by means of fishplates 28 made visible by a broken-up illustration of the cover elements. In analogy to the embodiment according to Figs. 1 and 2, the supporting beams formed in this manner extend, viewed in the rail longitudinal direction 23, to beyond the rims 22 of the 30 traffic surface 4. In analogy to the example according to Figs. 1 and 2, also in this case the supporting beams formed by the supporting beam parts 15a, 15b, 16a, 16b rest on a substructure of ballast 19, and the transverse sleepers 20 rest on a substructure of ballast 21, yet if desired, also in this 35 instance a different base carrying the supporting beams, on the 2558052_1 (GHMatters) - 9 one hand, and the transverse sleepers, on the other hand, can be chosen, such as a subgrade, e.g.. It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an 5 admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. In the claims which follow and in the preceding description of the invention, except where the context requires 10 otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments 15 of the invention. 2558052_1 (GHMatterS)