Prefabricated pipe gallery under railway combined reinforcing structure and construction method

Abstract

The application discloses a prefabricated pipe gallery under-rail joint reinforcing structure and a construction method, wherein a railway subgrade (2) is arranged above a prefabricated pipe gallery (1), support piles (5) are arranged in the railway subgrade (2), a D-shaped steel temporary beam (3) is arranged above the support piles (5) on the railway subgrade (2), and the support piles (5) at the end of the railway subgrade (2) and the D-shaped steel temporary beam (3) are connected through a joint anchoring structure (6). The prefabricated pipe gallery under-rail joint reinforcing structure and the construction method can reduce construction procedures and improve the safety of a track structure.

Description

Technical Field

[0001] This invention belongs to the field of railway subgrade. Specifically, this invention relates to a prefabricated pipe gallery combined reinforcement structure and construction method for railway underpass. Background Technology

[0002] Municipal engineering projects involving grade-separated crossings of railway lines are characterized by compact construction sites, tight construction schedules, and high safety requirements. However, with urban development, the number of grade-separated crossings of existing railway lines will increase, and the geographical locations and construction sites will become more complex and diverse. In particular, many technical challenges will be encountered in the jacking construction of large-section, long-stroke integrated utility tunnels, which need to be solved during construction.

[0003] To ensure the smooth jacking of the precast utility tunnel without interrupting the existing railway operation, it is essential to guarantee that the existing operating line does not deform, settle, or slip during construction. Therefore, it is necessary to reinforce the existing line before construction.

[0004] However, in the existing construction process, when the railway track is under a soft foundation, the conventional reinforcement method involves many overlapping construction procedures, slow construction progress, and insufficient reinforcement effect. It cannot meet the safety requirements of the existing track structure, nor can it achieve the goal of improving the efficiency of the tunnel construction and achieving safe and rapid passage. The existing construction method is also not suitable for railway lines with large cross-sections and long distances.

[0005] Utility model patent CN216892390U, published on July 5, 2022, discloses a railway subgrade reinforcement construction device. This device includes a fixed construction vehicle body, a hydraulic oil tank connected to the upper middle of the fixed construction vehicle body, an installation bracket connected to the upper left side of the fixed construction vehicle body, and wheels connected to the four corners of the lower end of the fixed construction vehicle body. This railway subgrade reinforcement construction device cannot reduce the construction steps of railway reinforcement or improve the safety of the track structure. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a prefabricated pipe gallery combined reinforcement structure and construction method for railway underpasses that reduces construction procedures and improves track structure safety.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The precast pipe gallery is reinforced by passing under the railway. The railway subgrade is located above the precast pipe gallery. Support piles are installed in the railway subgrade. D-shaped steel temporary beams are installed on the railway subgrade above the support piles. The support piles and D-shaped steel temporary beams at the ends of the railway subgrade are connected by a joint anchoring structure.

[0009] The combined anchoring structure includes a connecting steel plate located at the end of the railway subgrade. One end of the connecting steel plate is fixed to the side of the D-shaped steel temporary beam, and the other end of the connecting steel plate is provided with an anchor cable. The upper end of the anchor cable is fixed to the connecting steel plate, and the lower end of the anchor cable is fixed to the support pile.

[0010] The support piles are evenly spaced, and a pair of D-shaped steel temporary beams are provided on the support piles in the middle of the railway subgrade. The anchor cable passes through the connecting steel plate and passes through the support piles at the ends and middle of the railway subgrade in sequence.

[0011] The anchor cables on both sides of the railway subgrade cross through the support piles in the middle of the railway subgrade.

[0012] The upper end of the anchor cable protrudes from the connecting steel plate, and the lower end of the anchor cable protrudes from the support pile in the middle of the railway subgrade.

[0013] One end of the connecting steel plate is attached to the side of the D-shaped steel beam, and the other end of the connecting steel plate is set on the slope of the railway subgrade.

[0014] One end of the connecting steel plate is provided with a connecting bolt, and the connecting steel plate is fixed to the side of the D-shaped steel beam by the connecting bolt.

[0015] The combined anchoring structure is symmetrically arranged on both sides of the railway subgrade and is set at equal intervals on the railway subgrade.

[0016] The anchor cables are installed in pairs, and the connecting bolts are installed in pairs on the connecting steel plate.

[0017] The construction method for this type of prefabricated pipe gallery combined reinforcement structure under railway includes the following steps:

[0018] 1) First, excavate the support piles at the construction site, lower the steel cage, pour concrete, complete the pile foundation construction, and check the stability of the support piles.

[0019] 2) After the support piles pass inspection, clean up the ballast at the installation location of the D-shaped steel temporary beam and set up steel pads and plate rubber bearings to support the D-shaped steel temporary beam;

[0020] 3) Place the D-shaped steel temporary beams above the support piles, and lay steel crossbeams between the D-shaped steel temporary beams;

[0021] 4) Excavate working pits on one side of the D-shaped steel temporary beams at both ends of the railway subgrade;

[0022] 5) Install a combined anchoring structure, connect the connecting steel plate to the D-shaped steel temporary beam with connecting bolts, and use anchor cables to jointly reinforce the support piles at the lower end and middle of the railway subgrade;

[0023] 6) After installation, the anchor cables undergo grouting, tensioning, and sealing to complete the construction of the combined anchoring structure;

[0024] 7) Complete the jacking construction of the utility tunnel and the backfilling of earthwork around the utility tunnel, remove the steel crossbeams, restore the railway sleepers, and backfill the original railway track slag;

[0025] 8) Finally, crushed stone concrete was used to backfill the working pit to complete the reinforcement construction of the underpass railway.

[0026] The technical advantages of this invention are as follows: By adopting the prefabricated pipe gallery combined reinforcement structure and construction method for railway underpass, multiple reinforcement measures such as anchor cables and connecting steel plates are added, which improves the strength of the reinforced railway subgrade and ensures the safety of the railway track structure underpass; moreover, the construction process is simplified and the construction is safe and reliable; it can greatly improve the overall construction efficiency of pipe gallery underpass, and can quickly complete the reinforcement of railway lines and reduce construction costs.

[0027] This project solved the problem of construction difficulties when tunneling under weak foundation structures and existing operating railway lines. The installed support piles and anchor cables reinforced the original weak foundation structure, ensuring the safety of subsequent railway track operation. It also ensured the safety of the precast utility tunnel tunnel under existing railway lines while reinforcing the railway subgrade, thereby reducing the impact of the precast utility tunnel tunnel and foundation settlement on railway operation, saving overall construction time, and ensuring the safety of the existing track structure. Attached Figure Description

[0028] This manual includes the following figures, which illustrate the following:

[0029] Figure 1 This is a schematic diagram of the prefabricated pipe gallery combined reinforcement structure for railway crossing according to the present invention;

[0030] Figure 2 This is a side view of the prefabricated pipe gallery combined reinforcement structure for railway crossing according to the present invention;

[0031] Figure 3 This is a partial three-dimensional structural diagram of the prefabricated pipe gallery combined reinforcement structure for railway crossing according to the present invention;

[0032] Figure 4 This is a front view of the prefabricated pipe gallery combined reinforcement structure for railway crossing according to the present invention;

[0033] Figure 5 This is a schematic diagram of the joint anchoring structure of the prefabricated pipe gallery underpass railway reinforcement structure of the present invention.

[0034] The markings in the diagram are: 1. Precast pipe gallery; 2. Railway subgrade; 3. D-shaped steel temporary beam; 4. Steel crossbeam; 5. Support pile; 6. Combined anchoring structure; 7. Connecting steel plate; 8. Connecting bolt; 9. Anchor cable; 10. Working pit; 11. Steel rail. Detailed Implementation

[0035] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and to facilitate its implementation.

[0036] like Figures 1 to 5 As shown, the precast pipe gallery is a combined reinforcement structure for passing under the railway. The precast pipe gallery 1 is provided above the railway subgrade 2, and the railway subgrade 2 is provided with support piles 5. A D-shaped steel temporary beam 3 is provided on the railway subgrade 2 above the support piles 5. The support piles 5 and the D-shaped steel temporary beam 3 at the end of the railway subgrade 2 are connected by a combined anchoring structure 6.

[0037] The precast pipe gallery underpass railway joint reinforcement structure system consists of D-shaped steel temporary beams 3, support piles 5 and joint anchoring structure 6. The support piles 5 are part of the structure for reinforcing railway subgrade 2. A set of support piles 5 consists of three piles. The joint reinforcement structure connects the D-shaped steel temporary beams 3 and support piles 5 into one unit, achieving the reinforcement effect of railway subgrade 2.

[0038] like Figure 2 As shown, the combined anchoring structure 6 includes a connecting steel plate 7, which is located at the end of the railway subgrade 2. One end of the connecting steel plate 7 is fixed to the side of the D-shaped steel temporary beam 3, and the other end of the connecting steel plate 7 is provided with an anchor cable 9. The upper end of the anchor cable 9 is fixed to the connecting steel plate 7, and the lower end of the anchor cable 9 is fixed to the support pile 5. The combined anchoring structure 6 consists of the connecting steel plate 7, connecting bolts 8, and anchor cable 9. The connecting steel plate 7 is welded from steel and is used to connect the D-shaped steel temporary beam 3 and install the anchor cable 9. The D-shaped steel temporary beam 3 and the support pile 5 are then connected through the anchor cable 9.

[0039] Support piles 5 are evenly spaced. Pairs of D-shaped steel temporary beams 3 are installed on the support piles 5 in the middle of the railway subgrade 2. Anchor cables 9 pass through the connecting steel plate 7 and sequentially through the support piles 5 at the ends and middle of the railway subgrade 2. Steel crossbeams 4 are installed between the D-shaped steel temporary beams 3. The steel crossbeams 4 are evenly spaced between the D-shaped steel temporary beams 3 and are laid between the D-shaped steel temporary beams 3 to limit the spacing of the D-shaped steel temporary beams 3. The support piles 5 have reserved anchoring holes. Drilling is carried out using a drilling rig. The drilling depth is based on the anchor cable 9 being able to pass through the adjacent support pile 5 in the middle. The anchor cable 9 passes obliquely through the two support piles 5 at the ends and middle of the railway subgrade 2, which can improve the overall reinforcement effect of the combined anchoring structure 6 on the railway subgrade 2.

[0040] like Figure 2 As shown, the anchor cables 9 on both sides of the railway subgrade 2 cross through the support piles 5 in the middle of the railway subgrade 2. The lower ends of the anchor cables 9 on both sides of the railway subgrade 2 are fixed to the support piles 5 in the middle of the railway subgrade 2. This arrangement forms a stable triangular structure, which can improve the reinforcement strength of the support piles 5 and anchor cables 9, and effectively avoid the risk of deformation, settlement and slippage of the line during construction.

[0041] like Figure 3 As shown, the upper end of the anchor cable 9 protrudes from the connecting steel plate 7, and the lower end of the anchor cable 9 protrudes from the support pile 5 in the middle of the railway subgrade 2. The end of the anchor cable 9 protruding from the connecting steel plate 7 facilitates its fixation to the connecting steel plate 7, and the lower end of the anchor cable 9 protruding from the support pile 5 in the middle of the railway subgrade 2 facilitates the connection of the D-shaped steel temporary beam 3 and the support pile 5 into one unit, thereby improving the reinforcement effect.

[0042] One end of the connecting steel plate 7 is attached to the side of the D-shaped steel temporary beam 3, and the other end of the connecting steel plate 7 is set on the slope of the railway subgrade 2. With this installation method, one end of the connecting steel plate 7 is designed as an L-shaped structure so that it can fit tightly to the side of the D-shaped steel temporary beam 3. The connected steel plate 7 has high strength after installation. The other end of the connecting steel plate 7 is set at an angle to adapt to the construction slope of the railway subgrade 2. At the same time, it is convenient to set the anchor cable 9 at an angle, so that a single anchor cable 9 can pass through the two support piles 5 at the end and middle of the railway subgrade 2.

[0043] like Figure 5 As shown, one end of the connecting steel plate 7 is provided with a connecting bolt 8, and the connecting steel plate 7 is fixed to the side of the D-shaped steel temporary beam 3 by the connecting bolt 8. The connecting bolt 8 is used to fix the connecting steel plate 7 to the D-shaped steel temporary beam 3, and the upper end of the anchor cable 9 is fixed to the connecting steel plate 7 to prevent the anchor cable 9 from coming out.

[0044] like Figure 1 As shown, the combined anchoring structures 6 are symmetrically arranged on both sides of the railway subgrade 2 and are set at equal intervals on the railway subgrade 2. The symmetrical arrangement of the combined anchoring structures 6 on both sides of the railway subgrade 2 can ensure that the railway subgrade 2 is subjected to uniform stress after construction, thereby improving the structural strength and stability. The combined anchoring structures 6 can be set at equal intervals on the railway subgrade 2, which is suitable for long-distance railway construction and solves the shortcomings of existing technologies that cannot achieve long-stroke integrated utility tunnel jacking construction.

[0045] like Figure 5 As shown, the anchor cables 9 are installed in pairs, and the connecting bolts 8 are installed in pairs on the connecting steel plate 7. The pairing of anchor cables 9 can improve the connection strength of the anchor cable 9 connection. The upper end of the connecting steel plate 7 is provided with four connecting bolts 8, which can improve the connection strength with the D-shaped steel beam 3. The lower end of the connecting steel plate 7 is provided with two installation holes for anchor cables 9, which can facilitate the pairing of anchor cables 9.

[0046] The construction method for this type of prefabricated pipe gallery combined reinforcement structure under railway includes the following steps:

[0047] 1) First, excavate the support pile 5 at the construction site, lower the steel cage, pour concrete, complete the pile foundation construction, and check the firmness of the support pile 5.

[0048] 2) After the support pile 5 passes inspection, clean the ballast at the installation position of the D-type steel temporary beam 3, and set up steel pads and plate rubber bearings to support the D-type steel temporary beam 3.

[0049] 3) Place the D-shaped steel temporary beam 3 above the support pile 5, and lay steel crossbeams 4 between the D-shaped steel temporary beams 3;

[0050] 4) Excavate working pit 10 on one side of the D-shaped steel temporary beam 3 at both ends of the railway subgrade 2;

[0051] 5) Install the joint anchoring structure 6, connect the connecting steel plate 7 to the D-shaped steel temporary beam 3 by connecting bolts 8, and jointly reinforce the support piles 5 at the lower end and middle of the railway subgrade 2 by anchor cables 9;

[0052] 6) After installation, the anchor cables 9 undergo grouting, tensioning, and sealing to complete the construction of the combined anchoring structure 6;

[0053] 7) Complete the jacking construction of the utility tunnel and the backfilling of earthwork around the utility tunnel, remove steel beam 4, restore the railway sleepers, and backfill the original railway track slag;

[0054] 8) Finally, crushed stone concrete was used to backfill the working pit 10 to complete the reinforcement construction of the underpass railway.

[0055] To ensure the smooth jacking of the precast utility tunnel 1 without interrupting the existing railway operation, it is essential to guarantee that the operating line does not deform, settle, or slip during construction. Therefore, it is necessary to reinforce the existing line before construction.

[0056] like Figures 1 to 5 As shown, the specific construction method of this prefabricated pipe gallery under the railway reinforcement structure is as follows:

[0057] When reinforcing railway tracks using a combined reinforcement structure, the first step is to excavate the support piles 5, lower the reinforcing cage, pour concrete, and complete the pile foundation construction. The structural performance of the installed support piles 5 is then tested. After the support piles 5 pass inspection, a steel pad is first installed on the pier supporting the D-shaped steel temporary beam 3, and then a plate rubber bearing is installed on the steel plate.

[0058] After the support piles 5 are completed, the ballast at the location of the crossbeam is cleared, and the crossbeam is manually pulled into place using hooks. The D-shaped steel temporary beams 3 are pre-assembled using a ton crane. Pre-assembly involves first placing the side beams, then firmly connecting the bottom crossbeam and side beams. The D-shaped steel temporary beams 3 are located above the support piles 5, and steel crossbeams 4 are laid between the D-shaped steel temporary beams 3. The steel crossbeams 4 are evenly spaced between the D-shaped steel temporary beams 3 and can be used to limit the spacing of the D-shaped steel temporary beams 3.

[0059] After the D-type steel temporary beam 3, steel crossbeam 4, and support pile 5 are completed, a small working pit 10 is excavated on the outside of the D-type steel temporary beam 3. Setting up the working pit 10 can expand the construction space, facilitate construction operations, and make it easier to install the combined anchoring structure 6. Then, the combined anchoring structure 6 is installed, and the specifications of the combined anchoring structure 6 are adjusted according to the size of the small working pit 10.

[0060] Installation of the combined anchoring structure 6: First, tightly attach the combined anchoring structure 6 to the slope of the railway subgrade 2, and connect the connecting steel plate 7 to the D-shaped steel temporary beam 3 using four connecting bolts 8; then, utilizing the two pre-reserved anchoring installation holes below the combined anchoring structure 6, drill holes using a drilling rig, with the drilling depth determined by the support pile 5 in the middle of the railway subgrade 2. After drilling, place the anchor cable 9 into the corresponding installation hole, and after careful verification, use a combination of machinery and manual labor to slowly insert the anchor cable 9 into the hole. Two inclined long anchor cables 9 below the connecting steel plate 7 jointly reinforce the two support piles 5 at the end and middle of the railway subgrade 2. The combined anchoring structures 6 on both sides of the railway subgrade 2 are connected in this manner. When reinforcing long-distance railways, combined anchoring structures 6 can be installed at equal intervals on the railway subgrade 2.

[0061] After installation, the anchor cables 9 undergo grouting, tensioning, and sealing to complete the construction of the combined anchorage structure 6. Following this, the tunnel jacking and backfilling around the tunnel are completed, allowing for the removal of the steel crossbeams 4. The removal of the steel crossbeams 4 should follow the principle of "erecting before dismantling, and re-erecting before dismantling." First, the bottom crossbeams are removed and the railway sleepers are restored. After all the railway sleepers are restored, the longitudinal beams are lifted out, and the bottom is backfilled with the original railway track slag. Finally, the excavated small working pit 10 is backfilled with crushed stone concrete, completing the reinforcement construction for the underpass railway.

[0062] This type of precast pipe gallery combined reinforcement structure and construction method for railway underpasses can also be applied to similar underground engineering projects such as integrated precast pipe gallery 1 that pass under existing operating railway lines.

[0063] like Figures 1 to 5 As shown, when facing an existing operating railway line that passes under a weak foundation, in addition to reinforcing it with D-shaped steel temporary beams 3, steel crossbeams 4, and support piles 5, a small working pit 10 is excavated to set up a combined anchoring structure 6. The combined anchoring structure 6 is integrated with the D-shaped steel temporary beams 3 and support piles 5 to form a combined reinforcement system. After the integrated prefabricated pipe gallery 1 passes under the railway using the jacking method, the D-shaped steel temporary beams 3 and steel crossbeams 4 are finally removed, and the small working pit 10 is backfilled with crushed stone concrete.

[0064] The prefabricated utility tunnel underpass railway reinforcement structure and construction method adds multiple reinforcement measures such as anchor cables 9 and connecting steel plates 7, which improves the strength of the reinforced railway subgrade 2 and ensures the safety of the railway track structure underpass; moreover, the construction process is simple and the construction is safe and reliable; it can greatly improve the overall construction efficiency of the utility tunnel underpass, and can quickly complete the reinforcement of the railway line and reduce construction costs.

[0065] This project solved the problem of construction difficulties when tunneling under weak foundation structures and existing operating railway lines. The installed support piles 5 and anchor cables 9 reinforced the original weak foundation structure, ensuring the safety of subsequent railway track operation. It ensured the safety of the precast utility tunnel 1 tunneling under the existing railway line and reinforced the railway subgrade 2 foundation, thereby reducing the impact of the precast utility tunnel 1 tunneling under the existing railway line and ground settlement on railway operation, saving overall construction time, and ensuring the safety of the existing track structure.

[0066] The precast utility tunnel combined with railway underpass reinforcement structure and construction method has significant practicality and economic benefits. During the construction of a precast utility tunnel under an existing operating railway line in a certain city, testing showed that using this structure and construction method for railway track reinforcement significantly improved the overall construction efficiency of the utility tunnel underpass compared to traditional techniques. It quickly completed the reinforcement of the existing railway line, achieving good economic benefits with lower cost.

[0067] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A prefabricated pipe gallery combined reinforcement structure for railway underpasses, characterized in that: A railway subgrade (2) is provided above the precast pipe gallery (1), and a support pile (5) is provided inside the railway subgrade (2). A D-shaped steel temporary beam (3) is provided on the railway subgrade (2) above the support pile (5). The support pile (5) and the D-shaped steel temporary beam (3) at the end of the railway subgrade (2) are connected by a joint anchoring structure (6). The joint anchoring structure (6) includes a connecting steel plate (7), which is located at the end of the railway subgrade (2). One end of the connecting steel plate (7) is fixed to the side of the D-shaped steel temporary beam (3). An anchor cable (9) is provided at the other end of the connecting steel plate (7). The upper end of the anchor cable (9) is fixed on the connecting steel plate (7), and the lower end of the anchor cable (9) is fixed to the support pile (5). The anchor cables (9) on both sides of the railway subgrade (2) cross through the support pile (5) in the middle of the railway subgrade (2). The anchor cables (9) pass obliquely through the two support piles (5) at the end and middle of the railway subgrade (2). One end of the connecting steel plate (7) is attached to the side of the D-shaped steel beam (3), and the other end of the connecting steel plate (7) is set on the slope of the railway subgrade (2).

2. The prefabricated pipe gallery underpass railway reinforcement structure according to claim 1, characterized in that: The support piles (5) are set at equal intervals. Pairs of D-shaped steel temporary beams (3) are provided on the support piles (5) in the middle of the railway subgrade (2). The anchor cable (9) passes through the connecting steel plate (7) and passes through the support piles (5) at the end and middle of the railway subgrade (2) in sequence.

3. The prefabricated pipe gallery underpass railway reinforcement structure according to claim 1, characterized in that: The upper end of the anchor cable (9) passes through the connecting steel plate (7), and the lower end of the anchor cable (9) passes through the support pile (5) in the middle of the railway subgrade (2).

4. The prefabricated pipe gallery underpass railway reinforcement structure according to claim 1, characterized in that: One end of the connecting steel plate (7) is provided with a connecting bolt (8), and the connecting steel plate (7) is fixed to the side of the D-shaped steel beam (3) by the connecting bolt (8).

5. The prefabricated pipe gallery underpass railway reinforcement structure according to claim 1, characterized in that: The combined anchoring structure (6) is symmetrically arranged on both sides of the railway subgrade (2) and is set at equal intervals on the railway subgrade (2).

6. The prefabricated pipe gallery underpass railway reinforcement structure according to claim 4, characterized in that: The anchor cables (9) are arranged in pairs, and the connecting bolts (8) are arranged in pairs on the connecting steel plate (7).

7. The construction method of the precast pipe gallery underpass railway reinforcement structure according to any one of claims 1-6, characterized in that, Includes the following steps: 1) First, excavate the support piles (5) at the construction site, lower the steel cage, pour concrete, complete the pile foundation construction and check the firmness of the support piles (5); 2) After the support pile (5) passes inspection, clean up the ballast at the installation position of the D-type steel temporary beam (3) and set up steel pads and plate rubber bearings to support the D-type steel temporary beam (3); 3) Place the D-type steel temporary beam (3) above the support pile (5) and lay steel crossbeams (4) between the D-type steel temporary beams (3). 4) Excavate a working pit (10) on one side of the D-shaped steel temporary beam (3) at both ends of the railway subgrade (2); 5) Install the joint anchoring structure (6), connect the connecting steel plate (7) to the D-shaped steel beam (3) with connecting bolts (8), and reinforce the support piles (5) at the lower end and middle of the railway subgrade (2) with anchor cables (9); 6) After installation, the anchor cables (9) are grouted, tensioned, and sealed to complete the construction of the combined anchoring structure (6); 7) Complete the jacking construction of the pipe gallery and the backfilling of earthwork around the pipe gallery, remove the steel crossbeams (4), restore the railway sleepers, and backfill the original railway track slag; 8) Finally, crushed stone concrete was used to backfill the working pit (10) to complete the reinforcement construction of the underpass railway.

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