Journal of Surveying Engineering

A recent innovation for improved nearshore surveying and coastal engineering data collection is the Coastal Research Amphibious Buggy (CRAB). This 35‐ft (10.6‐m) high motorized tripod, when combined with a state‐of‐theart electronic total station, allows rapid, accurate surveying of the surf zone and nearshore waters out to depths of 30 ft (9 m). When compared to conventional methods, survey costs are reduced by an order of magnitude, and accuracy is vastly improved. Numerous other research applications have been achieved.

Accurate and complete information on underground municipal utility systems becomes increasingly important and difficult to maintain as cities grow and the urban infrastructure becomes more complicated. It is desirable to know the use, location, depth, size, material, age, active status, and ownership of every component of every underground utility system occupying public right‐of‐way. Such information is needed for operation and maintenance as well as for planning new construction. A scheme is presented for tabulating positional, functional, descriptive, historic, operational, and ownership information on utility system elements and sub‐surface structures in a format amenable to computerized data management. Grid coordinates and elevations are used for location. Coding schemes are suggested to convey other information. The advantages and disadvantages of the proposed scheme and considerations of implementation are discussed.

Applications of microelectronics and microcomputers in hydrographic surveying are growing rapidly. High accuracy, on‐site computations, navigation and data logging are made economically available. This paper presents examples of such recent developments as radio‐linked transit, a digital field plotter, and a digital depth sounder. All three of these examples were able to be developed and are produced in the environment of the user, thereby allowing ultimate fit to the needs of the surveyor. The specifications guidelines and applications of systems are given. The paper discusses the character of the growth of such applications as new capability is demonstrated. Economic decisions of lease versus purchase are considered as they relate to risk versus return.

The Land Records Repository of the Missouri Land Survey is a facility designed for the storage, recovery and reproduction of land survey information. The Repository performs several independent functions that collectively produce usable land survey information from processed raw data. Through the use of microfilm and computer, masses of land survey documents can be selectively recalled and reproduced at will. Over one‐half million land surveys from official government records, public records of 114 counties, the City of St. Louis and records of private surveyors are currently on file. The State of Missouri enjoys a reliable system of land records storage and retrieval through the Land Records Repository which supplies thousands of copies of records annually to government agencies, professional operations and the general public, reducing extensive research time, effort and cost. The end result is a Land Records Repository that has earned the respect of county and state agencies and has provided an awareness of the importance of properly recorded information.

Current technological developments place geodetic surveying in a transitional period from classical ground techniques to modern satellite‐based surveying methods. The current status of geodetic surveying is reviewed, followed by the identification of two major areas in which research is needed: Instrumentation and instrument performance; and specifications for surveys.

Inertial Surveying Systems are a very recent advance in surveying technology; they are the single most comprehensive geodetic positioning tool available today. Their historical development is briefly discussed and comments are made upon the specific interpretation of the geodetic parameters output by the system. Those systems commercially available are compared and state of the art accuracies given. These figures include recent results from an adjustment of a network of inertial traverses in which the accuracies obtained appear to be near the threshold of those possible with the present generation of hardware and its associated software.

If a perimeter control network is established on a construction site, electronic distance measuring equipment can be used to determine the positions on the site of points to be used in building layout. Radial surveying techniques can then be used for actual staking from the point so occupied. Analysis of such a procedure showed that staking point positions determined by averaging distance‐distance intersections to three perimeter control stations closely approximated a rigorous least squares solution for the same position. The need for geometrically strong intersections was recognized together with the need for sufficient perimeter control to enable such solutions. Baseline data for positional accuracy by radial staking is provided together with field techniques designed to minimize staking errors.

A simple approximate method of analyzing the accumulation (propagation) of random error in closed survey traverses is presented. With emphasis on the practical and approximate, a means of assessing survey quality is proposed to replace Relative Precision which has been found to be invalid for modern survey instruments. This technique, the Uncertainty Concept $\left(E_u\right)\text{,}$ has been validated in practice. Case studies demonstrate that $E_u$ enables detection of blunders and some unresolved systematic error. $E_u$ is also useful in estimating position tolerance to determine practical compliance with specifications employing this concept.

In one of the projects under consideration it was decided to observe a high accuracy and extremely dense gravity net. The accuracy and density requirement made it implicit to have an accurate knowledge of the position of the gravity stations being observed. The plan included full consideration for current theoretical and technological limitations, and the inherent distortions and inaccuracies of the available national control (with its impending improvement as NAD 83 and NAVD 88). Weightage also was given to the involved ruggedness of the terrain in some parts of the area to be surveyed, and the availability of instrumentations and other resources. Out of many potential techniques considered, a Doppler controlled Inertial Positioning System (IPS) survey approach was selected. The present paper discusses this concept and the special features found necessary for the project.

A three‐dimensional (3‐D) model based on the connectivity of astronomic and geodetic coordinate systems is developed from basic principles. It provides for simultaneous adjustment of most conventional types of terrestrial surveying observations. Observation equations express observed quantities in 3‐D space and are referenced to the local vertical at the point of observation. Classical reductions of observations to the reference ellipsoid prior to adjustment are not necessary. A least squares solution yields adjusted geodetic rectangular coordinates from which geodetic latitude, longitude and height values may be found. For most networks, astronomic coordinate values will also be obtained, but these values are probably reliable only if astronomic observations are included in the survey. The 3‐D model should provide a sound theoretical basis for development of a fully‐integrated adjustment model that includes conventional, photogrammetric, inertial, satellite and other surveying system observations. Additional research is desirable to evaluate the 3‐D method's full potential for applications such as local densification and project control surveys.