GNSS Levels Surveys

Levels Surveys - Levels-only surveys is a Value Management consideration. A full topographical survey might not be necessary. For a preliminary Environmental terrain study, for example, it may be adequate to simply acquire a grid of spot levels and then overlay them to an existing map or plan, such as a licenced OS index map extract or a Title Plan.

Sustainable - Using existing map data represents a sustainable approach by avoiding an unnecessary re-survey of documented detail and can provide a relatively large financial saving of as much as 80% over a full topographical, even accounting for OS licencing costs. Should a detailed survey be required at a later stage, we can easily integrate the two separate surveys since our topographical surveys are geo-positioned with GNSS RTK.

Process - We use our in-house process to plan a route for capture of the spot levels at required grid centers. This is uploaded to the GNSS RTK device. On site, the Surveyor is guided to each position in turn to quickly and efficiently capture each ground level. The surveyor can then freely capture levels at other key positions such as changes in gradient.

Quality Control - The GNSS RTK equipment constantly monitors the variable accuracy of the measurement. We use the in-built automatic quality-control thresholds to ensure that levels are not recorded unless they are within RICS and client specifications. Here we incorporate Total Station measurement where necessary when the GNSS RTK accuracy is generally sub-specification or there are issues with satellite or mobile phone coverage in parts of the site.

Terrain Models - We can also generate terrain models or contour lines from the point cloud, as illustrated above.