Introduction
Surveying is an essential discipline that plays a crucial role in various fields such as engineering, construction, mapping, and land development. One of the fundamental branches of surveying is plane surveying, which assumes the Earth’s surface to be flat, disregarding its curvature. This blog aims to provide an overview of plane surveying, its techniques, and its applications. We will explore the different methods employed in plane surveying, including chain surveying, plane table surveying, compass surveying, theodolite surveying, and leveling.
Plane Surveying
Plane surveying is primarily employed in situations where the area under consideration is small and relatively flat, making it convenient to treat the Earth’s surface as a plane. It simplifies calculations by assuming straight lines between points and plane angles for polygons. Although plane surveying offers lower accuracy compared to other surveying methods, it remains suitable for various applications.
Methods in Plane Surveying:
1.Chain Surveying
Chain surveying is the simplest and most basic form of surveying. It involves directly measuring linear distances on the ground using a chain or tape. Angular measurements are not considered in chain surveying. This method is suitable for small areas, level terrains, and large-scale mapping projects. Chain surveying is often employed in preliminary surveys and is useful for establishing reference points or initial data collection.
2.Plane Table Surveying
Plane table surveying utilizes a plane table, which is a drawing board equipped with a sighting device, to measure distances and directions. The surveyor takes visual observations and records them directly on the table by sketching or plotting. This method is commonly employed in small to medium-scale mapping projects, especially when high accuracy is not a requirement. Plane table surveying is efficient for fieldwork and enables immediate visualization of the survey area.
3.Compass Surveying
Compass surveying involves the use of a compass to determine directions of survey lines, while distances are measured using a chain or tape. This method is suitable for areas where the terrain is relatively open, allowing for easy line-of-sight observations. Compass surveying is often employed in preliminary surveys and reconnaissance work. It is important to note that compass surveying does not provide precise angular measurements, and therefore, it is not ideal for high-accuracy surveys.
4.Theodolite Surveying
Theodolite surveying employs a theodolite, an advanced surveying instrument, to measure horizontal and vertical angles accurately. The theodolite is mounted on a tripod and equipped with various features such as spirit levels, verniers, and telescopes. This method enables precise angular measurements, making it suitable for detailed surveys and engineering projects. Theodolite surveying is widely used in construction, mapping, and geodetic surveys.
5.Levelling
Levelling is a technique employed in surveying to determine height differences or elevations between different points on the Earth’s surface. It is essential for establishing benchmarks, calculating slopes, and designing drainage systems. The process involves using a levelling instrument, such as a level or a digital level, and a levelling staff. By measuring the difference in elevation between benchmark points, accurate contour maps and cross-sections can be created. Levelling is extensively used in construction projects, road engineering, and floodplain analysis.
Applications of Plane Surveying
1.Land development: Establishing boundaries and creating topographic maps for residential, commercial, and industrial projects.
2.Transport: Road construction, bridge design, and railway alignment.
3.Urban planning: Analyzing urban areas, designing developments, and mapping land use patterns.
4.Environmental studies: Assessing natural resources, conducting biodiversity surveys, and monitoring habitats.
5.Cartography and mapping: Creating accurate maps of roads, buildings, and terrain features.
6.Construction layout: Positioning structures accurately and establishing reference points.
7.Mining and quarrying: Mapping mineral deposits, determining lease boundaries, and monitoring excavation.
8.Property surveys: Establishing accurate boundaries and resolving boundary disputes.
9.Floodplain management: Assessing flood risks, designing drainage systems, and mapping flood-prone areas.
10.Archaeological surveys: Mapping archaeological sites, recording features, and understanding ancient structures.
For instance, when measuring a distance of 18.2 km, the variation between the arc length and the subtended chord is approximately 0.1 meters. Similarly, for a distance of 54.3 km, the difference amounts to around 0.3 meters. When measuring a distance of 91 km, the difference reaches approximately 0.5 meters.
Conclusion🎯
In conclusion, plane surveying is a fundamental branch of surveying that assumes the Earth’s surface to be flat for practical calculations. It involves methods such as chain surveying, plane table surveying, compass surveying, theodolite surveying, and leveling. Each method has its own advantages and is suitable for different types of surveys and mapping projects. While plane surveying may have limitations in terms of accuracy and applicability to large areas, it remains a valuable tool for numerous applications, contributing to the development and advancement of various industries.