What is Chain Survey?
Chain surveying is a very traditional method of surveying. In this method, we record only linear measurements, not angular measurements. Additionally, only measuring tasks are carried out in the field; all other tasks, including plotting and calculations, are completed in the office.
General Procedure In Making A Chain Survey
- Reconnaissance – We need to walk over the area to be surveyed and just note the general layout, like, the position of features, size and shape of the area.
- Choice of Stations – In this stage we need to decide upon the framework to be used and drive in the station pegs to mark the stations selected.
- Station Marking – When possible, station markers should be attached to permanent objects so that they can be quickly replaced if moved or located during the survey. Wooden pegs can be used on soft ground, and rails can be used on hard surfaces like roadways.
- Witnessing – In this step, we need to consists of making a sketch of the immediate area around the station showing existing permanent features, the position of the stations and their description and designation. The station point is then measured from at least three nearby features, and these measurements are recorded on the sketch.
- Offsetting – To avoid obstacles on the chain line, offsets are typically taken perpendicular to the chain line.
- Sketching – The longest line of the survey is typically used as the baseline and is measured first. Sketch the layout on the last page of the chain book along with the date and the name of the surveyor.