JP2023102899A - Ladder sleeper - Google Patents

Abstract

To provide a ladder sleeper capable of relaxing a force transmitted to a ballast.SOLUTION: A ladder sleeper 10 comprises a pair of vertical beams 12, an end closure beam 18 and an intermediate closure beam 21. The vertical beams 12 can be arranged below a pair of rails 5 extending in an X direction, and extend in the X direction. The end closure beam 18 is disposed near the end of the vertical beams 12 in the X direction, and extends in a Y direction. The intermediate closure beam 21 is disposed at a position nearer the center C of the vertical beams 12 than the end closure beam 18 in the X direction, extends in the Y direction, and is made of concrete.SELECTED DRAWING: Figure 2

Description

The present invention relates to ladder sleepers.

Ladder sleepers have been put into practical use for the purpose of saving labor for maintenance of ballasted tracks. Ladder sleepers are ladder-shaped sleepers in which long longitudinal beams made of prestressed concrete (PC) are arranged along rails and a pair of longitudinal beams are connected by steel joints (see, for example, Patent Document 1).

Japanese Patent No. 3217932

As rail vehicles travel over rail joints, shock loads act on the ballast. When rudder sleepers are placed in the joints of the rails, the rudder sleepers distribute the impact loads and transmit them to the ballast. The forces transmitted to the ballast through the rudder sleepers are less than the forces transmitted to the ballast through typical side sleepers. However, further mitigation of the forces transmitted to the ballast is required.

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a ladder sleeper capable of reducing the forces transmitted to the ballast.

The ladder sleeper of the present invention has a pair of longitudinal beams, an end beam and an intermediate beam. A pair of longitudinal beams is positionable below a pair of rails extending in the first direction and extends in the first direction. The end beams are positioned near the ends of the pair of longitudinal beams in a first direction and extend in a second direction that intersects the vertical direction and the first direction. The intermediate beam is positioned closer to the central portion of the pair of vertical beams than the end beams in the first direction, extends in the second direction, and is made of concrete.

In the first direction, near the center of the ladder sleeper is located at the joint of the rail. As rail vehicles travel over rail joints, shock loads act near the center of the rudder sleepers. The intermediate beam is positioned closer to the central portion of the pair of longitudinal beams than the end beams in the first direction. Impact loads are distributed by concrete intermediate beams and transferred to the ballast. This reduces the forces transmitted to the ballast.

The ladder sleeper has a plurality of mounting portions. A plurality of attachment portions are formed on a pair of longitudinal beams arranged in a first direction and used for attachment of a rail fastening device. The plurality of mounting portions includes a first mounting portion located next to the central portion of the pair of longitudinal beams in the first direction. The intermediate beam may be arranged at the position of the first mounting portion in the first direction.

In the first direction, the position of the first mounting portion of the ladder sleeper is arranged at the joint of the rail. When a railroad vehicle travels over a rail joint, an impact load acts on the first mounting portion of the ladder sleeper. The intermediate beam is arranged at the position of the first mounting portion in the first direction. Impact loads are well distributed by the intermediate beams and transmitted to the ballast. This significantly reduces the forces transmitted to the ballast.

The ladder sleeper has a plurality of mounting portions. A plurality of attachment portions are formed on a pair of longitudinal beams arranged in a first direction and used for attachment of a rail fastening device. The plurality of mounting portions includes a pair of second mounting portions located on both sides of the central portions of the pair of longitudinal beams in the first direction. The intermediate beam may be arranged at the position of the pair of second mounting portions in the first direction.

In the first direction, the central portions of the pair of second mounting portions of the ladder sleeper are arranged at the joint of the rail. When a railroad vehicle runs on a rail joint, an impact load acts on the pair of second mounting portions of the ladder sleeper. The intermediate beam is arranged at the position of the pair of second mounting portions in the first direction. Impact loads are well distributed by the intermediate beams and transmitted to the ballast. This significantly reduces the forces transmitted to the ballast.

The intermediate beam may be a double-ended beam that is fixed to both of the pair of longitudinal beams.
This ensures that the impact load is well distributed and transferred to the ballast. Therefore, the forces transmitted to the ballast are well mitigated.

The intermediate beam is a cantilever beam fixed to only one of the pair of longitudinal beams, and may be arranged only on one of the inner and outer sides of the pair of longitudinal beams in the second direction.
If the intermediate beam is a cantilever beam, the intermediate beam can be of a general reinforced concrete structure. If the intermediate beam is a beam with both ends fixed, it is necessary to apply tension to the PC steel rod from the viewpoint of crack prevention. This improves the productivity of ladder sleepers. If the intermediate beams are arranged only inside the pair of longitudinal beams, the ladder sleepers do not expand in the second direction. If the intermediate beams are arranged only on the outside of the pair of vertical beams, it becomes easier to compact the ballast on the inside of the pair of vertical beams.

The intermediate beam is a cantilever beam fixed to only one of the pair of longitudinal beams, and may be arranged both inside and outside the pair of longitudinal beams in the second direction.
This increases the contact area between the intermediate beam and the ballast bed. Impact loads are well distributed and transmitted to the ballast. Therefore, the forces transmitted to the ballast are well mitigated.

The intermediate beam of the present invention is arranged in the first direction closer to the center of the pair of vertical beams than the end beams, extends in the second direction, and is made of concrete. This significantly reduces the forces transmitted to the ballast.

1 is a perspective view of a ballasted ladder track using the ladder sleeper of the first embodiment; FIG. The top view of the ladder sleeper of 1st Embodiment. The top view of the ladder sleeper of 2nd Embodiment. The top view of the ladder sleeper of the 1st modification of 2nd Embodiment. The top view of the ladder sleeper of the 2nd modification of 2nd Embodiment. FIG. 11 is a perspective view of a ballasted ladder track using the ladder sleeper of the third embodiment; The top view of the ladder sleeper of 3rd Embodiment. The top view of the ladder sleeper of 4th Embodiment.

Hereinafter, a ladder sleeper according to an embodiment will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a perspective view of a ballasted ladder track using the ladder sleeper of the first embodiment. The ballast/rudder track 1 is a track in which a rudder sleeper 10 is laid on a ballast bed 3 . The ladder sleeper 10 is a ladder-shaped vertical sleeper arranged directly under the rail 5. - 特許庁The rail 5 is fixed to the ladder sleeper 10 by a fastening device 6 .

In this application, the Z direction, X direction and Y direction of the orthogonal coordinate system are defined as follows. The Z direction is the vertical direction and the +Z direction is the upward direction. The X direction (first direction) is the direction in which the rails 5 and the ladder sleepers 10 extend. The Y direction (second direction) is a direction perpendicular to the Z direction and the X direction. The X and Y directions are horizontal. In the X and Y directions, the side closer to the center of the ladder sleeper 10 may be called the inside, and the side farther from the center may be called the outside.

FIG. 2 is a plan view of the ladder sleeper of the first embodiment. The ladder sleeper 10 has a pair of longitudinal beams 12 , joints 14 and closed end beams (end beams) 18 . The ladder sleeper 10 is formed in a ladder shape by rigidly connecting a pair of vertical beams 12 with a plurality of joint members 14 .

The longitudinal beam 12 extends in the X direction. The longitudinal beams 12 are made of prestressed concrete (PC). PC is concrete prestressed by PC steel. A pair of longitudinal beams 12 are arranged in parallel and spaced apart in the Y direction. Mounting portions 16 used for mounting the fastening device 6 (see FIG. 1) are formed on the upper surfaces of the pair of longitudinal beams 12 . For example, the mounting portion 16 is a mounting hole into which a bolt is inserted. The mounting holes are formed one by one at positions corresponding to both sides of the rail 5 (see FIG. 1) in the Y direction. A plurality of mounting portions 16 are arranged side by side at substantially equal intervals along the X direction. The number of fastening devices 6 and mounting portions 16 in the X direction is not limited to the examples in each figure.

The joint material 14 is formed of a steel member such as a steel pipe or a steel rod. For example, the joint material 14 is formed of a straight deformed steel bar extending in the Y direction. The joint member 14 is arranged across the pair of longitudinal beams 12 . Both ends of the joining member 14 in the Y direction are embedded inside the pair of longitudinal beams 12 . A plurality of joint members 14 are arranged in parallel with intervals in the X direction. The joint material 14 may be formed of a steel pipe filled with mortar.

The end closing beams 18 are arranged near the ends of the pair of longitudinal beams 12 in the X direction. The end closing beams 18 extend in the Y direction. The end closing beam 18 is a fixed both ends beam that is fixed to both of the pair of vertical beams 12 . The basic structure of the end closing beam 18 is a reinforced concrete structure. However, in order to prevent cracking of the end closing beam 18, prestress (post-tension type) is additionally applied by unbonded PC steel material. The end closing beams 18 increase the contact area with the ballast bed 3 . The end closing beams 18 prevent the X-direction ends of the pair of longitudinal beams 12 from sinking into the ballast track bed 3 .

The ladder sleeper 10 has an intermediate beam 20 . The intermediate beam 20 is arranged at a position closer to the center portion C of the pair of vertical beams 12 than the end closing beam 18 in the X direction. The intermediate beam 20 extends in the Y direction. The intermediate beam 20 is made of concrete.

The intermediate beam 20 of the first embodiment is an intermediate closed joint beam 21 . The intermediate closed beam 21 is a fixed both ends beam fixed to both of the pair of longitudinal beams 12 . The width of the intermediate closing beam 21 in the X direction is the same as that of the end closing beams 18 . Thereby, the intermediate closing beams 21 do not interfere with the ballast compaction work inside the pair of longitudinal beams 12 .

The basic structure of the intermediate closing beam 21 is a reinforced concrete structure, similar to the end closing beam 18 . In order to prevent the intermediate closing beam 21 from cracking, prestress (post-tension type) is additionally applied by unbonded PC steel material. The construction method for the intermediate closing beam 21 is as follows. First, the formwork for the same part is assembled and the reinforcing bars are placed. Next, the PC steel material whose surface is unbonded is arranged at a predetermined position. Next, the PC steel material is primarily tensioned to remove slack. Next, concrete is placed and hardened, and prestress is applied to the longitudinal beams 12 . Next, the PC steel material is subjected to secondary tension to apply prestress to the intermediate closed beam 21 .

The plurality of mounting portions 16 described above includes a first mounting portion 16a. The first mounting portion 16a is located next to the central portion C of the pair of longitudinal beams 12 in the X direction. The intermediate closing beam 21 is arranged at the position of the first mounting portion 16a in the X direction.

The rail 5 has a seam S, as shown in FIG. A joint plate 7 is attached to the side surface of the rail 5 in the Y direction, straddling the joint S. Near the center of the ladder sleeper 10 in the X direction is located at the seam S. As shown in FIG. 2, the first mounting portion 16a of the ladder sleeper 10 and the intermediate closing beam 21 are arranged at the joint S in the X direction.

The fastening devices 6 attached to the first attachment portions 16 a fasten the ends of the rails 5 on both sides of the joint S in the X direction to the longitudinal beams 12 . Therefore, the first attachment portion 16a has attachment holes on both sides of the position corresponding to the joint S in the X direction. Thus, the first mounting portion 16a has two mounting holes at positions corresponding to both sides of the rail 5 in the Y direction.

The intermediate closing beam 21 supports the joint S at the same position as the joint S in the X direction. The seam S becomes a support seam supported by the so-called support seam method. The ladder sleeper 10 of the first embodiment is used for bearing seams.

In the X direction, the vicinity of the central portion C of the ladder sleeper 10 is arranged at the joint S of the rail 5 . When a railway vehicle travels on the joint S of the rail 5, an impact load acts near the central portion C of the ladder sleeper 10. As shown in FIG. The intermediate closing beam 21 which is the intermediate beam 20 is arranged closer to the center portion C of the pair of vertical beams 12 than the end closing beam 18 in the X direction. The impact load is distributed by the intermediate closing beam 21 and transmitted to the ballast. This reduces the forces transmitted to the ballast.

The position of the first attachment portion 16a of the ladder sleeper 10 is arranged at the position of the joint S of the rail 5 in the X direction. When the railway vehicle runs on the joint S of the rail 5, an impact load acts on the first mounting portion 16a of the ladder sleeper 10. As shown in FIG. The intermediate closing beam 21 is arranged at the position of the first mounting portion 16a in the X direction. The impact load is well distributed by the intermediate closing beam 21 and transmitted to the ballast. This significantly reduces the forces transmitted to the ballast. As a result, wear of the ballast and deterioration such as settlement of the ballast bed 3 can be suppressed.

The inventor of the present application performed a numerical analysis (simulation) on the pressure on the lower surface of the ladder sleeper 10 when an impact load acts on the first mounting portion 16a. When the intermediate closing beam 21 was present, the maximum pressure on the lower surface of the ladder sleeper 10 decreased by about 10% compared to when the intermediate closing beam 21 was absent. It was confirmed that the force transmitted to the ballast was sufficiently relieved by the intermediate closing beam 21 .

As described above, the X-direction width of the intermediate closing beam 21 of the first embodiment is the same as that of the end closing beams 18 . On the other hand, the width of the intermediate closing beam 21 in the X direction may be larger than that of the end closing beam 18 . As a result, the contact area between the intermediate closing beam 21 and the ballast bed 3 is increased, and the force transmitted to the ballast is sufficiently alleviated.

(Second embodiment)
FIG. 3 is a plan view of the ladder sleeper of the second embodiment. The ladder sleeper 10 of the second embodiment differs from the first embodiment in that the intermediate beams 20 are intermediate projections 22 . The description of the second embodiment that is the same as that of the first embodiment may be omitted.

The intermediate beams 20 of the second embodiment are intermediate protrusions 22 . The intermediate projection 22 is a cantilever fixed to only one of the pair of vertical beams 12 . The intermediate projection 22 is arranged only on the inner side of the pair of vertical beams 12 on the inner side and the outer side in the Y direction. The intermediate protrusions 22 protrude inward of the pair of vertical beams 12 in the Y direction. A pair of intermediate protrusions 22 are formed by protruding intermediate protrusions 22 from each of the pair of longitudinal beams 12 .

The intermediate protrusion 22 protrudes from the vertical beam 12 in the Y direction by a protrusion amount 22y. Although the intermediate protrusion 22 is a cantilever beam, since the amount of protrusion 22y is small, cracks are less likely to occur. The end closure beams 18 are prestressed while the intermediate projections 22 are of typical reinforced concrete (RC) construction. The work of primary tensioning and secondary tensioning of the PC steel material is unnecessary in the manufacturing process of the intermediate projection 22 . Therefore, the productivity of the ladder sleeper 10 is improved.

The X-direction width 22x of the intermediate projection 22 is larger than the X-direction width of the intermediate closing beam 21 of the first embodiment. The product of the protrusion amount 22y and the width 22x is the contact area between the intermediate protrusion 22 and the ballast track bed 3. As shown in FIG. The sum of the contact areas of the pair of intermediate projections 22 is equivalent to the contact area of the intermediate closing beams 21 of the first embodiment.

The intermediate protrusion 22 is arranged at the position of the first attachment portion 16a in the X direction. The first mounting portion 16a and the intermediate projection 22 of the ladder sleeper 10 are arranged at the seam S position. That is, the ladder sleeper 10 of the second embodiment is used as a bearing joint. When the railway vehicle runs on the joint S of the rail 5, an impact load acts on the first mounting portion 16a of the ladder sleeper 10. As shown in FIG. Impact loads are well distributed by intermediate projections 22 and transmitted to the ballast. This significantly reduces the forces transmitted to the ballast.

The intermediate projection 22 is arranged only on the inner side of the pair of vertical beams 12 on the inner side and the outer side in the Y direction. Since the intermediate projections 22 are not arranged outside the pair of vertical beams 12 in the Y direction, the ladder sleepers 10 do not expand in the Y direction.

FIG. 4 is a plan view of a ladder sleeper of a first modified example of the second embodiment. The ladder sleeper 10 of the first modified example differs from the second embodiment in that the intermediate projections 23 are arranged only on the outer sides of the pair of longitudinal beams 12 . The description of the first modified example that is the same as that of the second embodiment may be omitted.

The intermediate projection 23 protrudes outward in the Y direction from the pair of longitudinal beams 12 . The protrusion amount in the Y direction and the width in the X direction of the intermediate protrusion 23 are the same as those of the intermediate protrusion 22 of the second embodiment. Intermediate projection 23 is a typical reinforced concrete (RC) structure. The intermediate protrusion 23 is arranged at the position of the first attachment portion 16a in the X direction. The ladder sleeper 10 of the first variant is used for bearing seams. The intermediate projections 23 sufficiently distribute the impact load and transmit it to the ballast. Therefore, the forces transmitted to the ballast are well mitigated.

The intermediate projection 23 of the first modified example is arranged only on the outer side of the Y-direction inner side and outer side of the pair of longitudinal beams 12 . This facilitates the ballast compaction work inside the pair of longitudinal beams 12 in the Y direction.

FIG. 5 is a plan view of a ladder sleeper of a second modification of the second embodiment. The ladder sleeper 10 of the second modification differs from the second embodiment in that intermediate projections 22 , 23 are arranged both inside and outside the pair of longitudinal beams 12 . The description of the second modified example that is the same as that of the second embodiment or its first modified example may be omitted.

The intermediate protrusions 22 protrude inward of the pair of vertical beams 12 in the Y direction. The intermediate projection 23 protrudes outward in the Y direction from the pair of longitudinal beams 12 . The amount of protrusion in the Y direction and the width in the X direction of the intermediate protrusions 22 and 23 are the same as those of the second embodiment and the first modification. The sum of the contact areas between the intermediate projections 22 and 23 and the ballast track bed 3 is larger than the contact area between the intermediate closed joint beam 21 and the ballast track bed 3 in the first embodiment.

The intermediate projections 22 and 23 of the second modification are arranged both inside and outside the pair of vertical beams 12 in the Y direction. This increases the contact area between the intermediate projections 22 and 23 and the ballast track bed 3 . Impact loads are well distributed and transmitted to the ballast. Therefore, the forces transmitted to the ballast are well mitigated.

(Third embodiment)
FIG. 6 is a perspective view of a ballasted ladder track using the ladder sleeper of the third embodiment. FIG. 7 is a plan view of the ladder sleeper of the third embodiment. The ladder sleeper 10 of the third embodiment is different from that of the first embodiment in that it is used for hanging seams. Descriptions of the third embodiment that are the same as those of the first embodiment may be omitted.

As shown in FIG. 7, the intermediate beam 20 is arranged at a position closer to the center portion C of the pair of longitudinal beams 12 than the end closing beam 18 in the X direction. The intermediate beam 20 extends in the Y direction. The intermediate beam 20 of the third embodiment is an intermediate closed joint beam 21 made of concrete similar to that of the first embodiment.

The multiple mounting portions 16 include a pair of second mounting portions 16b. The pair of second mounting portions 16b are located on both sides of the central portion C of the pair of vertical beams 12 in the X direction. The intermediate closing beams 21 are arranged at the positions of the pair of second mounting portions 16b in the X direction. A pair of intermediate closing beams 21 are formed by arranging the intermediate closing beams 21 at respective positions of the pair of second mounting portions 16b.

The rail 5 has a seam S, as shown in FIG. A joint plate 7 is attached to the side surface of the rail 5 in the Y direction, straddling the joint S. A central portion of the ladder sleeper 10 is located at the seam S in the X direction. As shown in FIG. 7, the central portions C of the pair of second mounting portions 16b of the ladder sleeper 10 and the pair of intermediate closing beams 21 are arranged at the joint S in the X direction.

The fastening device 6 attached to the second attachment portion 16b fixes the rail 5 to the ladder sleeper 10 at a position away from the joint S in the X direction. Therefore, the second mounting portion 16b, like the other mounting portions 16, has mounting holes at positions corresponding to both sides of the rail 5 in the Y direction.

The intermediate closing beams 21 support the joint S at the positions of the fastening devices 6 on both sides of the joint S in the X direction. The seam S becomes a splice joint supported by the so-called splice method. The ladder sleeper 10 of the third embodiment is used for hanging seams.

The central portion of the ladder sleeper 10 is arranged at the joint S of the rail 5 in the X direction. When the railway vehicle runs on the joint S of the rail 5, an impact load acts on the central portion C of the ladder sleeper 10. As shown in FIG. The intermediate closing beam 21 which is the intermediate beam 20 is arranged closer to the center portion C of the pair of vertical beams 12 than the end closing beam 18 in the X direction. The impact load is distributed by the intermediate closing beam 21 and transmitted to the ballast. This reduces the forces transmitted to the ballast.

A central portion C of the pair of second mounting portions 16b of the ladder sleeper 10 is arranged at the position of the seam S in the X direction. When the railroad vehicle runs on the joint S of the rail 5, an impact load acts on the pair of second mounting portions 16b of the ladder sleeper 10. As shown in FIG. The intermediate closing beams 21 are arranged at the positions of the pair of second mounting portions 16b in the X direction. The impact load is well distributed by the intermediate closing beam 21 and transmitted to the ballast. This significantly reduces the forces transmitted to the ballast. As a result, deterioration such as ballast wear and subsidence can be suppressed.

(Fourth embodiment)
FIG. 8 is a plan view of the ladder sleeper of the fourth embodiment. The ladder sleeper 10 of the fourth embodiment differs from that of the third embodiment in that the intermediate beams 20 are intermediate protrusions 22 . Descriptions of the fourth embodiment that are the same as those of the third embodiment may be omitted.

The intermediate beams 20 of the fourth embodiment are intermediate projections 22 similar to those of the second embodiment.
The intermediate projections 22 are arranged at the positions of the pair of second mounting portions 16b in the X direction. A central portion of the pair of second mounting portions 16b of the ladder sleeper 10 is arranged at the position of the seam S in the X direction. That is, the ladder sleeper 10 of the fourth embodiment is used for the hanging joint. When the railroad vehicle runs on the joint S of the rail 5, an impact load acts on the pair of second mounting portions 16b of the ladder sleeper 10. As shown in FIG. Impact loads are well distributed by intermediate projections 22 and transmitted to the ballast. This significantly reduces the forces transmitted to the ballast.

The intermediate projections 22 of the fourth embodiment are arranged only on the inner side of the pair of longitudinal beams 12 in the Y direction, similarly to the second embodiment. Instead of the intermediate protrusion 22, an intermediate protrusion 23 similar to that of the first modified example of the second embodiment may be adopted. The intermediate projection 23 is arranged only on the outer side of the Y-direction inner side and outer side of the pair of vertical beams 12 . As in the second modification of the second embodiment, the intermediate protrusions 22 and 23 may be employed at the same time.

As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the specific configurations are not limited to these embodiments, and modifications, combinations, deletions, etc. of the configuration without departing from the scope of the present invention are included.

The intermediate beam 20 of the embodiment is arranged at the position of the first attachment portion 16a or the pair of second attachment portions 16b in the X direction. On the other hand, the intermediate beams 20 may be arranged between adjacent mounting portions 16 . Even in this case, the intermediate beams 20 are arranged closer to the center portions C of the pair of vertical beams 12 than the end closing beams 18 in the X direction. This reduces the forces transmitted to the ballast.

The end beams of the embodiment are closed end beams 18 , which are fixed ends beams fixed to both of the pair of longitudinal beams 12 . Alternatively, the end beams may be end projections similar to the intermediate projections 22,23. The end projections are cantilever beams fixed to only one of the pair of longitudinal beams 12 . End projections are common reinforced concrete structures. This improves the productivity of ladder sleepers.

C... Central part, S... Joint, 5... Rail, 6... Fastening device, 10... Ladder sleeper, 12... Longitudinal beam, 16... Mounting part, 16a... First mounting part, 16b... Second mounting part, 18... End closing beam (end beam), 20... Intermediate beam, 21... Intermediate closing beam (intermediate beam), 22... Intermediate projection (intermediate beam), 23... Intermediate projection (intermediate beam).

Claims (6)

a pair of longitudinal beams that can be arranged below a pair of rails extending in a first direction and extending in the first direction;
end beams arranged near ends of the pair of vertical beams in the first direction and extending in a second direction intersecting the vertical direction and the first direction;
an intermediate beam made of concrete, which is arranged at a position closer to the central portion of the pair of vertical beams than the end beams in the first direction and extends in the second direction,
Ladder sleepers. having a plurality of mounting portions formed on the pair of longitudinal beams arranged in the first direction and used for mounting the fastening device of the rail;
The plurality of mounting portions includes a first mounting portion located next to the central portion of the pair of longitudinal beams in the first direction,
The intermediate beam is arranged at the position of the first mounting portion in the first direction,
A ladder sleeper according to claim 1. having a plurality of mounting portions formed on the pair of vertical beams arranged in the first direction and used for fastening the rails;
The plurality of mounting portions includes a pair of second mounting portions located on both sides of the central portions of the pair of vertical beams in the first direction,
The intermediate beam is arranged at the position of the pair of second mounting portions in the first direction,
A ladder sleeper according to claim 1. The intermediate beam is a double-ended beam fixed to both of the pair of vertical beams,
A ladder sleeper according to any one of claims 1 to 3. The intermediate beam is a cantilever beam fixed to only one of the pair of vertical beams, and is arranged only on one of the inside and outside of the pair of vertical beams in the second direction,
A ladder sleeper according to any one of claims 1 to 3. The intermediate beam is a cantilever beam fixed to only one of the pair of longitudinal beams, and is arranged both inside and outside the pair of longitudinal beams in the second direction,
A ladder sleeper according to any one of claims 1 to 3.

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