Topographical Survey2021-01-20T11:45:36+00:00

2. Topographical Survey

2.1 Detail Physical feature surveying

Detail Physical feature surveying

Ground-based topographic mapping using real time kinematic global positioning system (RTK GPS) is a useful tool for collecting high resolution elevation data at the landscape level. RTK GPS is mobile, collects data quickly, and measures elevation within an accuracy of 1–5 cm.

In the early 1990s, RTK technology (Real Time Kinematic) was born and the GPS industry hasn’t looked back. RTK allows the user to obtain centimeter-level positioning in real-time. That is the point when using GPS for staking be-came possible and GPS for topographic surveys became very efficient. RTK is the fundamental technology that makes ma-chine control possible.

The basic concept behind RTK is that you have a base station receiver set on a known point somewhere around the project site. The base station receiver sends correction data to the surveyor who is operating the survey receiver (Rover). The correction data is typically sent via UHF or spread spectrum radios that are built specifically for wireless data transfer. The corrections from the base station receiver can be sent to an unlimited number of rovers. Real-time positions on the rover receiver are calculated as fast as 20 times per second or as little as once per second. For staking and topo where the rod person will be carrying the range pole (as in the picture at the right), once per second is plenty fast enough. coordinates used in the design file. Once that is done, you are ready to stake. You can work in Plane or an assumed coordinate system.

2.2 Contour surveying

Contour surveying in Bangladesh

Topographic map, cartographic representation of the Earth’s surface at a level of detail or scale intermediate between that of a plan (small area) and a chorographic (large regional) map. Within the limits of scale, it shows as accurately as possible the location and shape of both natural and man-made features. Natural features include relief, which is sometimes mistakenly understood to be the sole feature characterizing a topographic map, and hydrographic features, such as lakes and rivers; man-made features include other characteristics of the subject area, such as cities, towns, and villages, and roads, railroads, canals, dams, bridges, tunnels, parks etc.

2.3 Route surveying

A Route Survey is defined as being the required service and product that adequately locates the planned path of a linear project or right of way which crosses a prescribed area of real estate, extending from at least one known point and turning or terminating at another known point. Adequate location shall mean substantial compliance with the conditions and tolerances expressed in this standard. A route survey which defines new or proposed Alignment.

A Route Survey is usually required for the planning of a right of way, the acquisition of fee or easement property and for eventual construction layout work. The location of the facilities within the right of way is often held in respect to the center line or a right of way line. A Route Survey is made on the ground to provide for the location of right of way lines, a centerline, or reference lines in relation to property lines and terrain features.

Route Surveys shall include but are not limited to the proper location, monumentation, description or platting of the following routes:

  • Roadways, highways and railroads.
  • Transmission lines for communications, fuel, chemical, water and electrical needs.
  • Canals, waterways, drainage ditches and sewers.
  • View easements, air space easements, ingress and egress easements such as approach routes.

2.4 GIS Mapping

Survey Company in Bangladesh, Surveying and Mapping 35

A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data.  The key word to this technology is Geography – this means that some portion of the data is spatial.  In other words, data that is in some way referenced to locations on the earth.

Coupled with this data is usually tabular data known as attribute data.  Attribute data can be generally defined as additional information about each of the spatial features.  An example of this would be schools. The actual location of the schools is the spatial data.  Additional data such as the school name, level of education taught, student capacity would make up the attribute data.

It is the partnership of these two data types that enables GIS to be such an effective problem solving tool through spatial analysis.

GIS is more than just software. People and methods are combined with geospatial software and tools, to enable spatial analysis, management large datasets, and the display of information in a map/graphical form.

GIS can be used as tool in both problem solving and decision making processes, as well as for visualization of data in a spatial environment.  Geospatial data can be analyzed to determine (1) the location of features and relationships to other features, (2) where the most and/or least of some feature exists, (3) the density of features in a given space, (4) what is happening inside an area of interest (AOI), (5) what is happening nearby some feature or phenomenon, and (6) and how a specific area has changed over time (and in what way).