In view of the problem that the design standard of special railway is low and it is not high enough for tunnel portal girder erection operation, a technical improvement program is proposed, that is to lower the portal track structure height and the bridge girder erection machine working height. This paper analyzed the security and feasibility of this program. Good effects have been obtained after the implementation of the program. This method can provide reference for similar projects.%本文针对专用铁路设计标准偏低、隧道洞口架梁作业高度不足的实际问题，介绍了“降低洞口轨道结构高度和降低架桥机作业高度”的技术改进方案，文中详细分析了此方案的安全性和可行性，通过具体实施收到良好效果，谨供同类工程参考。
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