Surveying, Even though it is of diverse nature, there are some basic guidelines which are common to all branches of surveying. These guidelines have proved over the years to be vital if accurate surveys are to be conducted.
Guidelines for Accurate SurveyingThere are four most important guidelines which are to be followed to get accurate results of surveying.
- Initial Framework
1. Initial FrameworkProviding initial framework before spotting and setting the detail of a survey is the vital guideline of accurate surveying. The framework of survey means establishment of control points and subsidiary points. The control points should be established with higher accuracy than subsidiary points. By fulfilling this guideline, accumulation of inevitable errors can be eliminated and the occurred errors can be controlled within the framework. This process is also called as providing control.
2. PlanningPlanning is the second most important guideline of surveying. Most of the surveys are conducted without proper planning which results uneven effects on the cost of the project. In surveying cost and accuracy relationship is not linear. For example, if a length of 500 m is to be determined to an accuracy of either 5 mm or 0.5 mm, the cost ratio of respective accuracies may be the order of 1:300. Hence, increase in accuracy will have unbalanced effects on cost. With proper planning, one can choose required techniques, proper instruments for survey. By careful observation of the area, most suitable method for given topography can also be known. These all comes under planning. Time spent on planning and reconnaissance is never wasted.
3. CheckingTo eliminate or minimize the errors, sufficient independent checks at every stage of surveying is recommended. Every stage refers from field work to the final plotting. Checking means not only taking repeated measurements of the given line or area but also applying cross checks. The checking system should be independent and involved at all stages of surveying. Some examples of independent checks are as follows. Fieldwork Checking
- Check the distance of lines in both directions.
- Measure angles using theodolite
- Measure the diagonals of a quadrilateral.
- Summation check on angle observations of formed geometrical figure of area. For example summation of interior angles equal to (2n-4) x 90o.
- Apply cross checks for levelling measurements.
- Using angles and distances plot the important points of survey also use co-ordinates for accurate position of points.