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Before design and construction begin, accurate information about the terrain, buildings, roads, and utility networks must be obtained.
For this purpose, a geodetic survey is carried out, one type of which is a topographic survey of the site.
Although closely related, topographic and geodetic surveys differ in their purpose, scope, and final deliverables.
A topographic survey is a combination of field measurements and office processing, resulting in the preparation of a topographic plan of the site.
The plan shows terrain relief, buildings, structures, roads, fences, vegetation, and above-ground and underground utility networks.
A topographic survey of a land plot shows the actual position of objects and terrain features within an established coordinate and elevation system.
A geodetic survey is a broader concept that includes determining coordinates, elevations, distances, angles, and deviations of objects.
The result of a geodetic survey may be a topographic or geodetic site plan, an as-built drawing, a digital terrain model, a coordinate schedule, or a calculation of earthwork volumes.
The main types of geodetic surveys include topographic, as-built, façade, control, and horizontal and vertical surveys. Terrain surveys, utility network surveys, and measurements of building structures are also carried out.
The main difference between a geodetic survey and a topographic survey lies in the purpose of the result. A geodetic survey is used for a wide range of measurement and control tasks.
A topographic survey is carried out specifically to prepare a topographic plan of the area. For example, checking the deviation of a column or wall is a geodetic survey, but it is not a topographic survey.
Transferring the design axes of a building onto the site is also a separate type of work known as construction setting-out.
A topographic survey is part of geodetic works, but not every geodetic survey is considered topographic.
A topographic plan is a large-scale representation of a limited area prepared on the basis of measurements.
An engineering topographic plan contains conventional symbols, coordinates, elevation marks, terrain relief, and the actual position of objects. It may be provided both in printed and electronic formats suitable for use by designers.
A simple diagram without a scale, coordinate system, elevation marks, and information about the surveyor is not a complete topographic plan.
The content of the plan depends on the technical assignment, scale, and purpose of the survey.
It usually shows buildings, roads, fences, terrain relief, landscaping elements, manholes, poles, and utility networks.
Particular attention is paid to underground utilities. Their location is determined using as-built documentation, information from utility operators, inspection of manholes, and instrumental detection.
If the position of a utility network cannot be confirmed, this should be clearly indicated in the final survey materials.
A 1:500 topographic survey means that one centimetre on the plan corresponds to five metres on the ground.
Topographic surveying at a scale of 1:500 is commonly used for the design of buildings, external utility networks, roads, landscaping, and vertical planning.
However, the survey scale should not be selected simply because it is commonly used. It must take into account the size of the area, density of development, complexity of the terrain, and the designer’s requirements.
Types of topographic surveys differ depending on the method used to collect data and the intended purpose.
Ground surveys are carried out using electronic total stations, levels, and satellite receivers. A total station survey makes it possible to determine both horizontal and vertical positions of objects.
Aerial surveying may be used for large areas, but it still requires ground control and verification measurements.
An engineering topographic survey is carried out for design purposes and for preparing an engineering topographic plan.
An as-built survey records the actual position of completed structures and installed utility networks.
A topographic survey of a construction site is carried out before design solutions are developed.
It is required for new construction, reconstruction, external utility design, landscaping, earthwork calculations, and preparation of a general site plan.
A topographic survey for design is especially important on sites with complex terrain, dense development, and numerous underground utilities.
Geodetic surveying of a construction site helps identify existing constraints in advance and avoid conflicts between proposed structures and existing networks.
Geodetic surveying for private house construction also helps determine the correct location of the building, access roads, retaining structures, and utility connections.
A geodetic survey before and during construction is used for a broader range of tasks than a topographic survey.
It is required for checking excavations, piles, foundations, walls, floor slabs, and utility networks.
Geodetic measurements are also used to calculate earthwork volumes and verify whether completed structures comply with the design.
The result of the geodetic survey depends on the specific task. If a general site base is required, a topographic plan is prepared. If the position of a particular structure must be checked, a specialised drawing or measurement schedule is issued.
A topographic survey begins with the preparation of a technical assignment.
The assignment specifies the boundaries of the site, scale, coordinate system, list of objects to be surveyed, and the required format of the final materials.
After reviewing the source documentation, field geodetic works are carried out.
Specialists determine the coordinates and elevations of characteristic points and survey buildings, roads, utility networks, and terrain features.
The data is then processed during office work. The measurements are checked, processed, and transferred onto the topographic plan.
The survey is completed with an internal quality check for accuracy, completeness, and compliance with the technical assignment.
The main result of a topographic survey is a topographic plan of the site.
Depending on the task, the client may also receive a technical report, coordinate schedule, digital terrain model, and editable file for further design work.
The topographic plan must be prepared using the coordinate and elevation systems specified in the technical assignment.
The list of deliverables should be agreed in the contract before work begins. This helps avoid a situation in which the client receives only an image that cannot be used for further design.
Before accepting the survey, the scale, coordinate system, elevation system, and date of measurements should be checked.
The plan should show all buildings, roads, terrain features, and utility networks specified in the assignment.
It is also important to verify that the electronic file is suitable for use by the designer and that the positions of underground utilities are supported by the available source data.
Geodetic and topographic surveys solve related but different tasks.
A geodetic survey covers a broad range of spatial measurements, while a topographic survey is carried out specifically to prepare an up-to-date topographic plan.
Before starting the work, it is necessary to define the purpose of the survey, its boundaries, scale, coordinate system, and required deliverables.
A properly completed site survey reduces the risk of design errors, repeated measurements, and unexpected costs during construction.
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