| Geographic Positioning System (GPS) applications | | | | and optimization of GPS data obtained from site. |
| are widely used in engineering surveys such as in | | | | Hence, similar to traditional engineering surveying, |
| site surveying setting out, check and compliance | | | | accuracy management is essential when applying |
| surveys. The application of GPS become very | | | | GPS engineering Application to surveying. |
| complex and demanding, when it is used in | | | | Presently the GPS applications are popularly used |
| engineering projects such as bridges, dams, | | | | when developing local special geodetic networks |
| tunnels, high rise buildings which require precise | | | | for engineering projects. Such networks are small |
| deformation measurements. In essence, GPS has | | | | compared to large regionally and globally available |
| been a popular tool for long term monitoring of | | | | networks. To ensure reliability accuracy of these |
| civil engineering structures. Hence, GPS application | | | | testing models, it is essential to acquire large |
| on engineering survey implies accuracy and | | | | amount of experimental data for a considerable |
| reliability. | | | | period. Then the data is subject to various |
| As we know in engineering surveying, emphasis | | | | investigation and analyses with a view to improve |
| on error correction and accuracy is taken | | | | and optimize the observation and processing |
| seriously. In other words, an engineering surveyor | | | | procedures. |
| should know the accuracy and reliability limits of | | | | When GPS is used for measuring heights, it may |
| the surveying technique or method he uses. | | | | encounter constraints or limitations owing to lack |
| Hence, he has to use the most reliable, | | | | of exact knowledge and the condition of the local |
| economical, technically appropriate measuring | | | | geoid, particularly in mountain areas or proximity |
| technology for the intended purpose. | | | | to tall building. In such situation, it may have to |
| It is important to know about the real accuracy | | | | depend on observations made from different |
| limits of surveying methods. Thus when using | | | | directions using multiple satellite and receivers. |
| GPS, one should be aware of its applicability and | | | | Similarly, measurement of deformation needs high |
| limitations in engineering surveys. | | | | accuracy and require longer time and costs. In the |
| GPS applications use satellite technologies (which | | | | recent past, terrestrial methods were employed in |
| has comprehensive error correction procedures or | | | | many scenarios but now these have been |
| large error budgets) which allow reliability and | | | | substituted by GPS engineering survey |
| accuracy. The accuracy of GPS application in | | | | applications. |
| engineering survey depends on many factors that | | | | In the case of long term monitoring of structures, |
| depend on optimal observation parameters and | | | | static GPS applications are widely used. It can give |
| procedures using various standards and software | | | | relative position accuracy up to few millimeters |
| systems. The accuracy and reliability of GPS in | | | | based upon the time of observation and distance |
| engineering surveying greatly influenced by the | | | | of the reference station. By establishing |
| factors: | | | | permanent GPS stations can help you to maintain |
| 1) the satellite constellation system used, | | | | a reliable and consistent reference coordinate |
| 2) the atmospheric condition, | | | | system in the interested location. |
| 3) actual measuring condition of the observed site, | | | | There are many engineering surveying firms |
| 4) the quality of GPS instruments used and | | | | specialized in GPS application in engineering |
| 5) the procedures used for testing, processing | | | | construction. |