Engineering surveys gather data for use by planners and engineers. The products resulting from engineering surveys are generally topographic maps and/or a digital terrain model (DTM). Both conventional (on the ground) and photogrammetric methods are used to gather data for engineering surveys.
Engineering surveying involves:
- Investigating land, using measurement tools and geographic knowledge, to work out the best position to build bridges, tunnels and roads etc.
- Producing up-to-date plans which form the basis for the design of a project
- Setting out a site, so the structure is built in the correct location to the specified parameters
- Monitoring the construction process to make sure that the structure remains in the right position and recording the final built position
- Providing control points by which the future movement of structures such as bridges and dams can be monitored
How engineering surveys are conducted?
Engineering surveys are usually based on horizontal and vertical control, which consists of a series of fixed points located throughout a site whose positions must be determined on some coordinate system.
Horizontal control: defines points on a two dimensional horizontal plane which covers the site
Vertical control: is the third dimension added to the chosen horizontal datum.
The measurements for the control survey are taken using different types of equipment depending on the size of the site.
- In small sites typically theodolites, and tapes are used to observe horizontal control in the form of a traverse with levelling providing the vertical control
- In larger sites, total stations and digital levels are used.