Journal of Surveying Engineering

Since 1986, measurements of deformations have been made on a section of large‐diameter buried natural gas pipeline in northern Alberta. Precise conventional survey techniques are used to measure the deformations. Three‐dimensional translation components of the deformations are determined through the use of a survey network, while three‐dimensional rotation components of the deformations are determined by making special types of measurements with a one arc second theodolite. The monumentation required for this project, as well as the instrumentation, observational procedures, and analysis procedures used to determine the translations and rotations are described. The results indicate that part of the section of buried pipeline moved a significant amount in the downhill direction during the period from 1986, when the first survey was carried out, to 1989. This prompted a decision to excavate and rebury the entire section of line, and to continue monitoring deformations. Further remedial work, such as attempting to stabilize the slope or rerouting the pipeline, might be considered in the future.

Blunder detection is a topic of great interest to surveyors and mappers because undetected blunders significantly distort the solution. Therefore, a robust testing procedure has been developed for the detection and identification of multiple blunders in survey data. In the method, the theories of robust estimation and statistical hypothesis testing are successfully integrated to provide a reliable and unified testing process. The method can be applied to the case of multiple blunders and can greatly improve the detection and isolation of blunders as compared to the statistical testing of estimated residuals from a conventional least‐squares process. The conventional least‐squares procedure tends to smooth the blunder into good observations, whereas the proposed method does not. Two numerical examples are given to test and illustrate the performance of the proposed method for cases of single and multiple blunders.

In highway, railway, canal, and pipeline locations, the horizontal curves employed at points of change in direction are arcs of circles. A circular curve can be described by seven principal elements: (1) Radius of the curve; (2) deflection angle between tangents; (3) tangent distance; (4) external distance; (5) middle ordinate; (6) long chord; and (7) length of curve. In conventional surveying, the radius of the curve is given, and the deflection angle between the tangents is measured; all other elements can be calculated. However, these two elements sometimes are unknown in the fieldwork. In this case, a new method must be considered. In this paper, a numerical solution called the Newton‐Raphson's method is presented. Using this method, the radius of a curve and the deflection angle between the tangents can be calculated so long as two of the other principal elements are given. To be convenient for actual use, a computer program is included.