当输气管路上的地形起伏高差大于200米时，就应考率由于高差和地形起伏对输气管道输气能力的影响。When the relief elevation difference on the pipeline road is greater than 200 meters, the influence of elevation difference and relief on the gas transmission capacity of the pipeline shall be considered.这样的输气管道可以看作不同坡度的直管段连接而成。Such pipelines can be regarded as straight sections of different slopes connected.每一直管段的始点和终点就是线路上地形起伏较大的特征点，特征点之间的微小起伏可忽略。The beginning point and the end point of each straight pipe segment are the feature points with large topographic fluctuation on the line.