Journal of Surveying Engineering

Global positioning system (GPS) equipment, the world's best electronic distance measuring machines (EDMs), are becoming faster and easier to use. Not only does one use this new portable equipment to establish distance, but three‐dimensional positioning is quickly available. The use of GPS as a tool for accomplishing boundary surveys; topographic surveys; location surveys; control surveys for GIS/LIS, photogrammetry, national, state and local coordinate systems; and other land surveys is here to stay. Kinematic GPS, the latest use of the system is now a reality. Initially, 45 min to 2 hr of data collection was required to obtain first‐order work (1:100,000). One can now establish a new point with as little as 90 sec of data while maintaining the same first‐order accuracy. Further, it has been shown by actual field use that one can maintain sufficient signal strength to move from point to point while collecting data. Very little data is required to obtain the three‐dimensional position of the new point. The move can be made by vehicle or on foot.

In 1985, the Arizona Department of Transportation (ADOT) adopted a new program called “Contractor Staking.” Intended to reduce overall construction engineering costs, this new concept has revolutionized ADOT's approach to highway construction. Since that time, several important changes in the contracting industry have occurred. Contractors must now be more cognizant of incorporating timely and quality‐survey activities into their work plans. Meanwhile, ADOT has been able to reduce the time spent on surveying and shift it to the administration and inspection of an increased highway‐construction workload. Analysis has shown that direct costs and savings due to “Contractor Staking” have essentially cancelled each other in the last five years. However, substantial savings have been achieved due to ADOT's ability to administer a larger construction workload with the same number of personnel. In addition, the savings in indirect costs, such as delay claims and claims resulting from survey errors, are real and significant. “Contractor Staking” is a viable approach to maximizing the benefit derived from the public works dollar.

Electronic total stations and data collectors have come to be recognized as vital productivity tools in the age of digital mapping. Information encoded in data collectors represents the first and, perhaps, most important link in the information chain from field data collection to data presentation and data management. Unfortunately, data collectors today have largely been designed to function well within a user‐ or manufacturer‐defined hardware and software environment. Outside the designed environment, the efficacy of most data collectors deteriorates because of their inability to cooperate fully with other hardware and software systems. This paper proposes the standardization of a neutral‐file fomat, initial data collector exhange format (IDCXF), for integrating diverse data‐collector systems. The concept of entity coding for point‐line features in the context of CAD/GIS mapping is also proposed for examination.

AS we enter the second decade of automated geographic information systems, important technology trends are emerging that will have a strong impact on how these systems are used and by whom. No longer are departmental systems hidden in the back room, accessible only to the technocrats. Today, cooperating organizations require an approach through which the system is accessible to a diverse blend of nontechnical users with differing applications. These multiparticipant groups also demand technology capable of managing the distribution of data to these numerous end users. To accommodate these requirements, six important trends have evolved: Continuous geographic coverage, spatial‐relational data‐base management, topological structures, distributed processing, content management, and open hardware and software architectures. This paper describes these trends and their impact on multiparticipant, multiapplication geographic information systems.

Land subsidence measurement is usually based on a comparison of bench‐mark elevations surveyed at different times. These bench marks, established for mapping or the national vertical control network, are not necessarily suitable for measuring land subsidence. Also, many bench marks have been destroyed or are unstable. Conventional releveling of the study area would be costly and would require several years to complete. Differences of as much as 3.9 ft between recent leveling and published bench‐mark elevations have been documented at seven locations in the Sacramento Valley. Estimates of land subsidence less than about 0.3 ft are questionable because elevation data are based on leveling and adjustment procedures that occurred over many years. A new vertical control network based on the Global Positioning System (GPS) provides highly accurate vertical control data at relatively low costs, and the survey points can be placed where needed to obtain adequate areal coverage of the area affected by land subsidence.

The relatively new technology known as geographic information system (GIS) has many possible uses for engineers who have projects covering large geographic areas. The many categories of data that can be included in a GIS provide the user with valuable resource data that can be combined with or subtracted from other categories to create entirely new categories. GISs come in two basic forms—raster or vector—and each has its advantages and disadvantages. Raster systems assign attributes to specific ground locations, and the resultant output is in the form of typewriter symbols, while vector systems assign attributes to polygons and have outputs that are visually more attractive. GIS technology is widely used by planners, and use by engineers is increasing. Advances in marrying the GIS software with better graphics reproduction software and increased exposure to GIS have brought about increased use by engineers.