Journal of Surveying Engineering

This paper presents new solutions in the area of general transition curves. General transition curves describe a curvilinear transition between two rectilinear directions using only one equation. The curves ensure continuous change of curvature all over the curvilinear transition. Along such curves, the curvature rises from zero at the start point to a certain maximum value, and then drops to zero again at the end point. The present paper introduces two new families of general transition curves: with smooth and nonsmooth curvature diagrams. This means that the general transition curves could be considered as an alternative to the geometric systems formed by classical geometric elements (first transition curve – circular arc – second transition curve; first transition curve – second transition curve). The use of general transition curves is advantageous from the viewpoint of vehicle motion dynamics. It also extends the possibilities of modifying the arc geometry to obtain the assumed radius of curvature.

Methods based on integer ambiguity determination, such as the least-squares ambiguity decorrelation adjustment (LAMBDA) method, are currently used for precise global navigation satellite system (GNSS) differential positioning. In the present paper, the author proposes an ambiguity-free method based on a dedicated mixed (stochastic/deterministic) optimization algorithm that, unlike the LAMBDA method, is capable of providing reliable and accurate results using few observation epochs (e.g., 1-cm accuracy with just two epochs), having the additional advantages of insensitivity to cycle slips and impossibility of wrong ambiguity fixation. In addition, it is demonstrated that the application of the linear (deterministic) part of this algorithm yields the correct baseline results much more easily and quickly than methods requiring integer ambiguity determination, provided the initial approximate coordinates are accurate to a few centimeters. However, the use of ambiguity-free methods requires that the integer character of the ambiguities be preserved so that they can be eliminated; therefore no ionosphere-free combination can be computed and the methods are valid only for short baselines (e.g., less than 10 km).

The local tie vectors between different space geodesy instruments in colocated sites, such as the global navigation satellite system (GNSS), very long baseline interferometry (VLBI), and satellite laser ranging (SLR), are essential for combination with the international terrestrial reference frame (ITRF). This paper introduces the surveying method and data processing model for determining the tie vectors in the seven colocated sites in Shanghai, Wuhan, Kunming, Beijing, Xian, Changchun, and Urumqi, and presents the values and full variance-covariance of these local ties. The surveying methodology and data processing method of the current work are rigorously determined to guarantee the relative positional precision of reference points (RPs) of different instruments in each colocation site to be a few millimeters. This paper compares the new tie vectors with those derived from ITRF 2008 products to consider the discrepancies at tie epoch. By comparing the new results to the previous results by other organizations, the new tie vector at the Wuhan site is in good agreement, but the vertical coordinate difference of the tie vector at the Shanghai site is as large as 2.24 cm. Therefore, the tie vector at the Shanghai site may have changed about 2 cm from 2003 to 2011.

Various corrector surface models are proposed to mitigate systematic height errors to fit the orthometric heights determined by combining the Tainan City real-time kinematic (RTK) global positioning system (GPS) network and the local geoid model data to the published orthometric heights. Several data sets for Tainan City were tested and analyzed. Two geometric geoid models and one gravimetric-geometric geoid model were generated using the GPS and leveling data. Consequently, three types of orthometric heights were determined (Models I, II, and III). The selection of the optimal corrector surface model for different models was based on a series of statistical tests. The test results show that (1) the selection of the optimal corrector surface model is highly related to the geoid model generating method, hence the optimal corrector surface models are a fifth-degree polynomial for Models I and II and a seven-parameter similarity transformation for Model III; and (2) the determined orthometric height is accurate to 2–4 cm after applying an optimal corrector surface model.

The existence of circular tanks is a present reality in the modern day industry. These structures can play various types of functions for the storage of a wide range of products, such as liquids, gases, oil wastewater, and granular solids. Safety concepts form the basis of any structure design and assessment code. Detailed information about the structural deformation can help to determine the health of structures as well as to evaluate whether such deformation is the same as what the structure was designed to tolerate. The main purpose of a structural deformation monitoring scheme and analysis of cylindrical oil storage tanks is to detect any significant movements or displacements of these structures. An effective approach is to model the circular tank by using well-chosen discrete points located on the surface of the tank which, when situated correctly, accurately depict the characteristics of this tank. It can then be said that any movements of those points represent deformations of the object. This paper outlines the procedure of a geodetic monitoring system of circular oil storage tanks and presents an analysis of the observations to determine the values of their deformation. A methodology for structural data analysis of monitoring the structural deformation of circular oil storage tanks is also presented. This paper also presents a method for determining the distortion of a circular cross section of a tank by determining the radius and coordinates of the center of this section using a least-squares adjustment technique.

Gantry cranes load and unload containers from container ships. To ensure safety and operation, the deflection of their main beams under load should be analyzed. This deflection depends on the weight of the loaded container as well as on the position of the trolley that moves the container. For this study, a bivariate polynomial model is built to estimate the deflection based on these two inputs. This two-dimensional load-dependent model is developed in four steps in order to determine the shape of the deflection (dependent on the trolley position) as well as its magnitude (dependent on the container weight). A specific gantry crane was monitored with several sensors where five are inclinometer sensors that observe the tilt along the crane’s main beam and two are tacheometers that observe the trolley position and the absolute deflection. By collecting data from 18 loading operations, the parameters of the deflection model are estimated. Based on this data, the deflection under load is processed dependent on the container weight and trolley position. The verification of the entire model shows deviations within $\text{±}4\hspace{0.17em}\text{mm}$ in comparison with an independent loading operation. This quality is acceptable regarding the measurements used.

As technology in the manufacture of total stations evolves rapidly, a new era in surveyor's field work arises. This paper describes appropriate instrumentation, software, and possibilities for communication that are needed for realization of a remote survey. With a remote survey, the surveyor can sight, measure, help, or check with collaborators in the field, without being at the designated site. Applying a remote survey in specific applications, the user can target, choose, and check the targets and also have a complete view of the field work in progress, at any given time, from an office or at home or other remote locations. The utilization of free software and appropriate instrumentation combined with wired or wireless connections allows the remote overall control and handling of a total station without additional costs. The pros and cons of this procedure are presented. Additionally the first successful results of remote targeting accuracy, achieved via computer, are presented. Finally useful discussion and further investigational tips are highlighted. The described method is intended to support specific surveying applications or scientific and academic research and is not for professional land-surveying work.