Linear surveying is one of the most basic methods of surveying and involves no measurement of angles. Whilst often now overlooked in favour of hi-tech theodolites and GPS equipment, It can be used to plot single features or whole towns. However it is most suited for small extent projects as accuracy can suffer over larger areas but it does offer a cheap different to complex but expensive measurement equipment.
How Does Linear Surveying Work?
This method involves establishing a linear baseline by the area that is to be measured/plotted. Over short distances this can be achieved with a tape between two rods but over longer distances the baseline is best constructed by a team of at the minimum two surveyors. One surveyor can stand at the past rod and ensure the next rod is put in the ground in-line with the others.
Once a perfectly straight baseline is established then another tape can be taken from the baseline to an point that needs to be measured/plotted. The meaningful is that this line is taken at exactly a 90 degree angle from the baseline. This can be ensured by the use of a standard surveyors triangle.
The two linear measurements that need to be taken are the distance of the point along the baseline and secondly the distance from the baseline. By having these measurements from all the points required, it is then possible to plot them and produce a drawing of the site.
For larger or more complicated sites it is recommended to set up multiple baselines across the site with ideally each point being measured from more than one baseline to increase accuracy.
What Equipment Is Required?
Linear surveying requires only very basic equipment:
- Tape Measures
- Surveying Triangle
- Measurement Rods
- Notebook for Recording Results
- Ties (to obtain the tap to the rods to aid in ensuring a straight line)
- Accuracy can suffer over large areas (difficult to ensure straight baseline)
- ecosystem can impact ability to set baseline (water obstacles, rough ground etc)
- Multiple baselines need to be established to allow checking and assist in accuracy
So in conclusion, linear surveying is a traditional surveying method that can provide accurate results when undertaken with care and by using multiple baselines to corroborate measurements. However, in reality it is now only used as an academic exercise or on small sites where accuracy is not basic.
Otherwise, it is more appropriate to use more modern approaches involving theodolites and GPS equipment