Differences in Rail Standards and Adaptation Principles
Where are the differences in dimensional tolerances between national standard rails and UIC standard rails?
National standard rails have stricter control over dimensional tolerances of rail height and base width, with rail height tolerance usually ±0.5mm and base width ±0.6mm, such as the standard rail height of 60kg/m national standard rail is 176mm. UIC standard rails have a relatively wider tolerance range, with some models having a rail height tolerance of up to ±0.7mm and base width tolerance of ±0.8mm. This difference stems from the national standard's higher requirements for track geometric accuracy in high-speed lines, while the UIC standard balances versatility across multiple scenarios. Different dimensional tolerances affect the fit between rails and fishplates, clamping plates, requiring targeted matching of accessories. When selecting, the rail standard should be determined based on the line type (high-speed, conventional speed), and then accessories with corresponding tolerance ranges should be matched.
Why is 75kg/m national standard rail preferred for heavy-haul railways?
Heavy-haul railways have high axle loads and traffic volumes, requiring extremely high load-bearing capacity and wear resistance of rails. The 75kg/m national standard rail has a larger cross-sectional area and stronger bending resistance. This type of rail meets the requirements for tensile strength and has excellent impact toughness, effectively withstanding the repeated impact loads of heavy-haul trains. Compared with 60kg/m rails, it has a lower wear rate, which can extend the line maintenance cycle and reduce long-term operating costs. The compatibility of the national standard 75kg/m rail with Type VI spring clips and Type IV sleepers has been verified over a long period of time, and the system stability is more reliable. The selection of rails for heavy-haul lines should be based on axle load and traffic volume data, and the 75kg/m rail is the main model recommended by China State Railway Group for heavy-haul lines.
How to coordinate the compatibility between rails and foreign-standard accessories in transnational railway projects?
Transnational railway projects should first clarify the dominant standard, such as the China-Laos Railway prioritizing Chinese standards and the Hungary-Serbia Railway balancing UIC standards. If foreign-standard rails (such as AREMA 132RE) are selected, corresponding specifications of spring clips and gauge blocks need to be matched to ensure the clamping force matches the rail cross-section. It is necessary to verify the dimensional tolerances of accessories; the rail head width of foreign-standard rails may differ from national standards, requiring customized compatible fishplates and clamping plates. Fastening systems compatible with multiple standards can be selected to reduce compatibility conflicts between different standards. When necessary, third-party testing should be conducted to verify whether the connection strength and compatibility between rails and accessories meet the line requirements.
What are the core performance characteristics of Japanese JIS standard rails?
Japanese JIS standard rails focus on heat treatment processes, adopting online residual heat quenching technology to ensure the uniformity of the structure of the rail head and web. They have excellent fatigue performance, with some models capable of withstanding 5 million cycles of load without cracks, suitable for the frequent start-stop working conditions of urban rail transit. The dimensional accuracy control is balanced, achieving a good balance between wear resistance and toughness, suitable for Japan's mountainous terrain and small curve radius line conditions. This standard rail needs to be matched with special insulated fasteners to meet the requirements of its track circuit system. When selecting, attention should be paid to the thread specification difference between it and national standard bolts to avoid connection failure.
Why has the U75V model become the mainstream choice for high-speed railways among national standard rails?
The U75V national standard rail has high tensile strength and good wear resistance, fully meeting the operational requirements of high-speed railways with a speed of 250km/h and above. By the end of 2024, the laying mileage of U75V rails in national high-speed railways accounted for 86%, and its reliability has been verified through practical application. It has excellent welding performance, meeting the long rail welding needs of seamless lines, and reducing vibration and wear caused by track joints. This model of rail has the best compatibility with Type V spring clips, providing stable clamping force and longitudinal resistance. High-speed railway lines have extremely high requirements for rail consistency. The U75V has a mature production process and strong quality stability, making it the preferred model for high-speed railways designated by China State Railway Group.