What is a construction survey?
A construction survey is a survey done on a construction site to mark construction activities and for laying out positions for construction equipment. It includes evaluating and estimating construction activities before the beginning of the project.
A construction survey is basically a type of preparation done before the actual construction begins. This survey involves analyzing the land topography, locating the construction site, locating the reference points, etc. After the construction plan has been made for the building, the next prior process is to do a land survey by the construction surveyor. The construction surveyor uses the total station to perform a pre-construction survey which includes boundary surveys and determining horizontal control lines. The main idea of a construction survey is to plan the process of construction and note down all the reference points and locations of the construction activities and then match them with the true values obtained by the end of the construction. A topographic survey is also done by the construction surveyor to give an “as-built” survey report.
Elements in construction surveys
- Confirm the location of the construction site.
- Stake-out reference points for new structures.
- Structure layout
- Survey of drainage system example, measuring the diameter of the manholes.
- Collecting control data like vertical and horizontal control data.
- Mapping of the construction project.
- Topographic surveys.
- Design data is calculated in a CAD file.
- Documentation of site conditions.
- Elevation of the new structures.
Role of a construction surveyor
A construction surveyor plays a key role in the surveying of the construction site. Following are the duties performed by the surveyor:
- Measuring angles on the construction site from one reference point to other.
- Research work is done based on the records of the land.
- Boundary lines are measured with the help of utility tools.
- Results of surveying are saved and later checked for accuracy and corrections.
- By using surveyed records, maps and plots are made of the construction project.
- The maps and survey records are presented to the property owner or clients.
- Performing topographic surveys, taking account of both vertical and horizontal control.
In field work, it is very necessary to take field notes. These notes are very important in surveying point of view, as all the survey points and data are written in them at the time when the survey was performed. This gives ease for rechecking and retaliating the records of the survey performed. In this field book, data should be written in clear words without erasing. The field book should contain the name of the construction surveyor, equipment used for the survey, weather, and date. After taking down the readings, daily records should be signed. Notes are taken in the form of numerical, sketches, and explanatory notes.
In office work, a construction surveyor performs drafting, computing, and designing duties. In drafting preparation of plans and scaling is done for topographic surveys. With the help of field data, project planning has to be done both manually and in software. By using CAD and STAAD PRO loads and other measurements are calculated. For existing building structures calculations are done in the same manner.
A stake-out survey in a construction project involves inserting a wooden stake in the ground to survey the location for improvements. A stake-out survey is done by the land surveyor which makes the blueprints and maps of the construction site, which help in progressing a construction from plan to actual structure. In construction, a stake is used for foundations, columns, curbs, etc.
Equipment and Techniques
Construction equipment includes heavy machinery doing earthwork and excavation depending upon the type of project. Basic construction activities include digging, leveling, compacting, placement, moving earth to long distances, etc. construction equipment requires proper use in the presence of the contractor. Proper use of the construction equipment results in smooth construction, time management, safety, and economic affordability. There are different types of construction equipment for example bulldozers, excavators, backhoes, etc.
Surveying equipment plays a key important role for construction surveyors to start a project and can also be used in middle or at the end of the project. In conventional methods chain and tape are used for linear measurement and compass or theodolite is used for angular measurement. Leveling was done using dumpy level and leveling staff. These conventional methods prove to be long and tedious for the engineer and the reading noted was not very precise. An engineer would verify those readings manually to get correct records. So for the easement of the engineer modern techniques of surveying equipment was introduced. Modern equipment for the surveys are:
EDM: Electronic distance measurement instrument is used to get distances and directions of the required reference point. This instrument work on the propagation of radio or light waves.
Total stations: This is dynamic equipment that can give a measurement of both distances and angles. Total stations also have a built electronic field book to store all the readings of the survey performed.
GPS: Global positioning system gives the precise location of the given reference point using a satellite system. It is of great easement for an engineer as well as a construction surveyor.
Automatic level: This instrument is basically used for leveling because it keeps the line of sight or line of collimation fixed even the device is tilted.
Coordinate system used in land survey
A land survey is basically performed based on geodesic coordinates that’s why a construction surveyor has to convert the coordinates to the coordinates used in the existing project. Coordinate systems used by land surveyors are Cartesian coordinate systems, building grids, chainage or station systems, etc.
Context and Applications
Construction surveys play an important role in both field work as well as in studying subjects because without doing a land survey, one could not start a project or do the construction works.
Engineers should hold the knowledge of surveying before starting any construction activities or to establish a career in civil engineering. This is an important subject in civil engineering and is taught in the following courses:
- Bachelors of Technology in Civil Engineering
- Masters of Technology in Civil Engineering
- Masters of Technology in Structure Engineering
1. Which of the following instrument is used in land survey?
- Total stations
Correct option- b
Explanation: Total stations are used to take the electronic measurement in a land survey. All the other options are an example of construction equipment.
2. What is the most common instrument used for a land survey?
- Automatic level
Correct option- a
Explanation: Theodolite is the most common method for a land survey as it can measure both angles and distance.
3. Which of the following are the instrument errors in a land survey?
- Heat waves
- Reading error
Correct option- c
Explanation: Parallax is the error caused by the instrument, heat waves and refraction are the natural errors while reading error is the human error.
4. Who of the following person performs a stake-out survey?
- Chief engineer
- Property owners
- Government agencies
- Land surveyors
Correct option- d
Explanation: Land surveyors perform the stack-out survey by placing the stack on the reference points, property owners and government agencies are the authorities that own the project and chief engineers are the head of engineers.
5. Which of the following type of survey is done for the construction of a building?
- Hydrographic survey
- Geological survey
- Deformation survey
- Construction survey
Correct option- d
Explanation: Construction survey is the main survey done for constructing a building or roadway. A geological survey is done to make maps of the geological features of the earth. Hydrographic survey is done for coastlines.
- Civil engineering survey
- Construction equipment
- Construction site work
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