A monitoring survey always starts with the initial setup of the monitoring targets and local survey control network. The targets are fixed to the structure in the pre-designated locations utilising either glue or drilled screws.
Without a fixed monitoring point to resurvey each time the consistency will be poor or non-existent. Fixed points are installed on to the structure and usually consist of survey prisms or reflective target stickers. When using prisms they are typically secured using screws drilled into walls or using high strength glue.
A local survey control network also needs to be installed. This involves placing survey targets (prisms or reflective survey points) away from the site. These are used by the total station as a way of calculating it’s precise position each time a monitoring survey needs to be undertaken.
A monitoring survey is undertaken using a piece of equipment called a total station. A total station is a high accuracy optical instrument that is used to measure distances and angles. Total stations are usually mounted on tripod legs whereby the operator can look through the lens and record survey points. In some cases, automation is required If so a total station can be left in a safe location and operated remotely.
At each survey interval, the total station has to be set up using the local control network. Once set up accurately, the monitoring survey process can be undertaken. Each monitoring point is precisely surveyed using the total station and recorded to the instrument.
Once this data has been reached the office, it is uploaded to the monitoring survey software which can generate data to illustrate movement (or lack of) over time.