# The Development of the Pipe Jacking Guidance Technology
## 7 Analysis of Pipe Jacking Projects  
### Cases of Projects  
As shown in Table 2, the prismatic method has been used for a long time and is suitable for larger pipe diameters due to the space limitations of the prismatic method. The pipe jacking project of the Yanqiao branch line of the Qingcaosha water source from Shanghai is divided into two sections, consisting of a starting shaft and two receiving shafts, so as to realize the simultaneous jacking of two rows of pipelines in close proximity [28]. The project adopted the RMS-TV system. Six prisms were placed on the wall of the starting shaft for precise orientation of the total station both above and below the shaft. During operation, the communication power supply was turned on, the total station was leveled and roughly aimed at one of the prisms and the start function key on the manual operation console was pressed, and the system would automatically and continuously perform measurements. [PERSON] [29] developed a pipe jacking guidance system based on the prism method for the Jianxin-Shennong transmission line pipe jacking project in Fuzhou City, Fujian Province, China. Since the radius of curvature reaches 300 m, a single total station cannot complete the measurement work. It is necessary to add a total station in the pipeline, and the control terminal drives the total station in turn to complete data collection, transmission and processing. In the Yangcheng Lake diversion project, the second water source of Suzhou City, China, the single jacking distance reached 2670 m. As the jacking distance of the pipe jacking machine increases, the total station cannot aim at the prism at the pipe jacking machine. The total station fixed in the working well is placed in the pipeline at a position where it can aim at the prism and move with the pipeline. During the measurement process, the rear-view prism in the starting shaft is repeatedly aimed for orientation. When the rear-view prism cannot be aimed, the rear-view prism is installed in the pipeline and moved with the pipeline, thereby achieving long-distance pipe jacking [30]. As shown in Table 3, the MTG series and TUnIS Navigation MT series developed by Shanghai MIDU Measurement Technology Co., Ltd. and VMT Germany have been applied in long-distance and curved-pipe jacking projects. At close distances, the prism method is used. When the distance is too great or the pipeline is curved, the laser target method is used for guided measurements, in which the laser total station is placed inside the pipeline. In recent years, long-distance and curved-pipe jacking projects have developed towards smaller diameters, which makes it impossible to deploy the total station inside the pipeline. Therefore, for smaller pipe diameters, such as the Power Tunnel project in Taiwan, China, and the Drainage Services Department's sewer pipe project in Hong Kong, China, the TUnIS Navigation MTGyro system, based on the inertial guidance method, was used to complete the measurements. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Time** & **Project Name** & **Content** & **Guidance Accuracy** \\ \hline
2010 & \begin{tabular}{c} Pipe jacking project of \\ Yanqiao branch line \\ \end{tabular} & \
\begin{tabular}{c} Pipe diameter: 3.6 m; \\ Distance: 1119 m and 1004 m \\ \end{tabular} &
\begin{tabular}{c} Horizontal and vertical \\ deviation: \(\pm\)75 mm \\ \end{tabular} \\ \hline
2013 & \begin{tabular}{c} Pipe jacking project of \\ Jianxin-Shennong \\ transmission line \\ \end{tabular} & \
\begin{tabular}{c} Pipe diameter: 3.2 m; \\ Distance: 412 m \\ Radius of curvature: 300 m \\ \end{tabular} &
\begin{tabular}{c} Horizontal and vertical \\ deviation: \(<\)100 mm \\ \end{tabular} \\ \hline
2020 & \begin{tabular}{c} Yangcheng Lake \\ Diversion Project \\ \end{tabular} & \
\begin{tabular}{c} Pipe diameter: 2 m; \\ Distance: 2670 m \\ \end{tabular} &
\begin{tabular}{c} Horizontal deviation: \(\pm\)50 mm \\ vertical deviation: \(\pm\)70 mm \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}