Topographical surveys

Topography is the study of shapes & features of land surfaces. Topographical surveys are used to determine the depth, elevation, size and location of any man-made or natural land feature.
Land surveying is the first step for any land development or construction project. Topographical surveyors get accurate insights about the property, such as site measurements, boundary area, terrain quality, etc.
Traditional topographic surveys involved maps and manual inspections. These traditional methods require the land surveyors to physically survey the site. Resulting they are time-taking and often prone to human errors. The new and improved topographical surveys use drones and 3D laser scanners which allow surveyors to cover hundreds of acres in a few hours.
With drones and other aerial surveying tools, a land surveyor can easily get accurate data about the terrain, vegetation, soil quality, land elevation, boundary measurements and more.
Usage of drones for construction inspections are prevalent in many countries like USA, UK, Europe & Australia. Architects, engineers, and construction professionals often outsource land surveys and site data collection activities to drone surveying companies.
Use of Topographical Surveys
Topographical surveys help with accurate data collection. With regards to construction industry, it forms an important part of the pre and post construction stages. Here are a few uses of topographical maps:
Accurate property measurements
Topographical survey data is crucial during the planning and site assessment stage of a construction project. Without a topographical survey, the architects and engineers would have no idea about the property measurements.
The data collected from a topographical survey helps architects prepare the initial working prototypes and designs (2) It also allows the on-site engineers to understand the terrain, land elevations, breaklines and landfills beforehand. Breaklines are a group of terrain points where there is a significant change in the elevation of the ground surface.
Understanding land terrain
Using a topographical survey, engineers can clearly understand the soil quality, land elevation, vegetation, nearby water bodies, and other elements. It is essential to get these insights before beginning the construction work. Architects and on-site engineers can use this data to identify terrain obstacles such as debris, any building, or man-made structure that needs to be demolished.
Identifying construction costs
Topographical surveys are usually conducted in the initial site visitations to plan the project according to the terrain of the land. This gives them a fair idea of the area measurements and construction equipment needed to commence the project. These details are necessary for resource allocation, cost evaluation, and risk management activities.
Deciding project deadlines
Topographical surveys using drones or 3D laser scanners allow surveyors to focus on specific areas around the property. They are also more efficient with usage of time and resources when compared to traditional land surveying methods. Understanding land terrain also helps engineers set tentative project deadlines. The modern-day aerial surveying tools such as drones and LiDARs give real-time insights of the property. It allows engineers to take quicker decisions, optimize resources and save on costs.
Construction documentation and paperwork
The insights collected from topographical surveys also help simplify the pre-construction paperwork. Engineers and builders often use images collected from topographical surveys for project proposals and reports. Drones and 3D laser scanners simplify this process. The survey data can be processed in photogrammetry software and converted to any file format.
Commercial drone surveying is supervised by a central body duly appointed by the government of the country. For instance, usage of all unmanned aerial vehicles fall under the supervision of CASA in Australia to ensure safe and regulated survey operations. Drone operators who conduct topographical surveys must have a CASA license and adhere to the drone flight rules.
Steps Involved in Topographical Survey
A topographical survey includes the following steps:
* Gathering Information about the property
* Planning the survey schedule and pricing
* On-site survey
* Processing survey data
* Quality check and analysis
* Converting survey data into accessible format
Architects, engineers and construction professionals (AEC) outsource the land surveying activities to certified land surveyors. They hire certified land surveyors to inspect the property and provide accurate measurement data. Land surveyors use their industry experience to plan their topographical survey based on the topology of a specific piece of land.
Step 1: Gathering information
A land surveyor conducts an initial consultation with the project manager, to discuss the specific survey requirements. This is followed by a physical site visit if needed to help with planning the topographical survey. Here, the land surveyors would conduct a manual site inspection wherein they check the scope and project plan of the topographic survey.
Step 2: Planning the Survey
The land surveyor plans the survey in this stage which involves the determination of the key aspects of the survey:
* Purpose of the survey
* Accuracy of the survey based on project requirement
* Use the survey data and necessary formats for usage by architects, builders and engineers.
* Budget estimate and resources needed to carry out the survey.
Step 3: Conducting the survey
Conducting the actual survey and preparing a topographic map can take anywhere between a couple of days to a couple of weeks, depending on the size, accessibility and scalability of the project. With the advent of drones, surveying companies use these Unmanned Aerial Vehicles (UAVs) and LiDAR scanners to collect survey data. This makes the process easier, quicker, and more efficient with usage of time and resources.
Step 4: Recording/Processing survey data
The last step in a topographical survey is to convert the survey footage into images, 3D maps, models, and other accessible formats. Topographic mapping or modelling simplifies the site footage. Drones and 3D scanners simplify the process of carrying it out at the site of the survey. The final output may be processed either by using a photogrammetry software or 3D modelling software, to convert the raw drone data or modify the existing footage.
Step 5: Quality Assurance and Analysis
The land surveyor conducts quality checks to ensure that the survey data is accurate, free from errors, has been effectively captured and formatted. Land surveyors work with a quality assurance team that checks the quality of the survey data before producing the final output. Experienced land surveyors who are experienced in surveys related to AEC industry can also help AEC professionals further with the analysis of the survey data to take real-time decisions.
Step 6: Delivery of final output
The last stage of a topographical survey is the final output. The output can wildly vary depending on the specific project objectives. A few common formats in which topographical survey data can be accessed are maps, 3D models, animations, 2D images etc.
See Also
# Cadastral Surveying
# Topographic maps
# History of topographic maps
# Topographic map symbols

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