短隧道定线原系易事。隧道加长，则定线工作，十分困难。因通常隧道多从两端开凿或先凿井后再分别各端开凿。查各端开凿，在光线不充、空气恶劣、潮湿、拥挤导坑中进行一切工作，自非易事。隧道长度较短，则无论在直线上或在曲线上，并容易办理，大体不外将地上中线，慎重移入地下。如于两端导坑开凿之外，再求由侧面推进，则更需要相当计算丈量。总之短隧道定线，如熟知普通测量方法，已足应付。 Short tunnel alignment was originally easy. When the tunnel is lengthened, the alignment work is very difficult. Due to the tunnel usually more than from both ends of the cut or first sinking, respectively, each end of the cut. Check each end cut, in the light is not filled, poor air, humidity, cradles lead all the work, since not easy. Short tunnel length, both in a straight line or on the curve, and easy to handle, generally not outside the ground, carefully moved into the ground. Excavated at both ends of the pit, and then seek advance from the side, you need to calculate quite a measurement. In short, short tunneling, such as familiar with the common measurement methods, have enough to meet.