Horizontal and Vertical Control
Horizontal and vertical control are developed to create a framework around which other surveys can be adjusted. These control surveys are used for accurate mapping projects in the construction of underground utility systems, roadways, power lines, tunnels, and many other high precision projects. Gresham and Associates, Inc. incorporates a complete range of Global Positioning technology including Static GPS, Real Time Kinematic (RTK) and OPUS control to provide high precision solutions for horizontal and vertical control monumentation.
Horizontal Control Surveys
Horizontal control surveys coordinate horizontal positional data. These positions can be referenced by parallels or plane coordinate axes. Because they are used as a framework for other surveys, these surveys must be precise and accurate. These surveys provide a network of monuments or points on the ground that can be used as the control for any other surveying project, such as a boundary or construction survey. The advantages of using a horizontal control survey is that lost monuments can be replaced accurately, surveys can be coordinated, more than one network station can provide a check to the work, and a reduction in the cost of the project can be achieved. Most horizontals should (and will) be connected to the control network.
Vertical Control Surveys
A vertical control survey determines elevation with respect to sea level. These surveys are also used as a benchmark upon which other surveys are based and high degree of accuracy is required. These surveys are useful for tidal boundary surveys, route surveys, construction surveys and topographic surveys. In a vertical control system, at least two permanent benchmarks should be used, but more may be required depending upon the needs and complexity of the project. These projects are needed for the construction of water and sewer systems, highways, bridges, drains, and other major town or city infrastructure. These surveys can be done alone, but are often done in conjunction with a horizontal control survey.
The National Oceanic and Atmospheric Administration (NOAA) maintains the National Geodetic Survey to which all vertical control surveys should be connected for reference. For more information about the National Geodetic Survey or the standards for vertical control surveys, please visit the NOAA website.
For more information on horizontal and vertical control, please email us or call 806.359.9648.