“Surveys are really important for construction work. They help make sure things are in the right place and at the right angle, like how tall something should be or how steep a slope needs to be for a building or a plant layout. Different survey terms are used to describe these measurements.”
importance and application of surveying in construction
In this article, we will read
In this article, we will read about the importance and application of surveying in construction. It covers key concepts like pre-construction and post-construction surveys, leveling, the sequence of surveying steps, and the role of surveying during different stages of a construction project. It highlights the need for accurate measurements, alignment, and elevation control to ensure quality and compliance with standards throughout the construction process.
Surveying:
is about figuring out where things are on the ground or on buildings. It helps us understand the shape and size of land or structures and put that information on maps or plans.
Leveling:
Leveling in construction refers to the process of determining and showing the relative heights or elevations of different points on the ground or within a structure.
The sequence to be followed for the survey concerning the start of the work is as follows:
The work is divided into two parts:
A. Starting a new project involves establishing the main grid lines and benchmark with reference to a known datum or reference point to begin the new work.
B. For a pour in an existing structure, we use existing references or benchmarks within the structure to determine the location, alignment, and elevation of the pour.
The application of surveying in everyday construction activities.
Before we talk about how surveying is used in different construction activities, we need to follow these steps carefully:
- Mark reference lines on each building floor for checking various activities.
- Place benchmarks on each building floor accurately.
- These steps are crucial because the accuracy of our checks depends on these reference points.
After that, we use surveying for:
- Creating the building layout.
- Checking floor elevations using benchmarks.
- Inspecting formworks for alignment and verticality within specific tolerances:
- Section dimension tolerance is ± 5 mm.
- Verticality tolerance is 5 mm per 5 meters but shouldn’t accumulate.
- Checking critical EPs (Established Points) for location and elevation:
- Before concreting, tolerance is ± 2 mm.
- After concreting, tolerance is ± 6 mm.
- Angular tolerance is ± 0.500.
Surveying holds significant importance during different stages of a construction project:
- Pre-construction Stage: Before construction begins, surveying helps in planning and designing by providing accurate measurements of the land and identifying potential challenges.
- During Construction Stage: Surveying is key for ensuring that construction activities are carried out according to the planned layout, alignments, and elevations. It helps in quality control and verifying that the work meets the required standards.
- Post-construction Stage: After construction, surveying is essential for final checks, as-built drawings, and documenting the completed work accurately.
Site engineers must understand the necessity and value of surveying throughout these stages. Some specific requirements include:
A pre-construction survey is necessary for the following purposes:
- Defining the plant area using a 20m x 20m plant grid pattern with existing permanent references.
- Locating various plant structures within the established grid.
- Establishing specific benchmarks for commencing work within buildings or structures.
- Marking and identifying parts of the structure in different pours at various elevations with respect to the defined benchmark/reference.
- These markings can be done using:
- Theodolite
- Measuring tapes
- Dumpy level
- Total station
- Initially, during construction, the reference point is marked on reference pillars located 2-3 meters away from the structure’s edge.
- After construction, this reference is transferred to a permanent structure, and subsequently, all references are taken from this common reference point to avoid any cumulative errors.
| No. | Area of Survey During Construction | Description |
|---|---|---|
| 1. | Maintaining alignment of walls and position of embedded parts, pipe supports, piping sleeves, etc. | Ensures proper placement and alignment of structural elements. |
| 2. | Maintaining the location of EPs (Established Points), especially critical EPs. | Critical for accuracy in structural positioning and measurements. |
| 3. | Keeping the top elevation of the concrete plate EPs / Critical EPs constant. | Ensures correct elevation levels for structural components. |
| 4. | Ensuring the concrete’s top elevation remains consistent while finishing the green cutting process. | Ensures accuracy in the finishing stages of construction. |
| 5. | Maintaining the slopes of floors. | Ensures proper drainage and functionality of floors. |
| 6. | Maintaining the levels of sumps. | Critical for drainage systems and water management. |
| 7. | Ensuring the location of PVC water stop during concreting. | Essential for maintaining waterproofing and structural integrity. |
A post-concrete survey is necessary for the following reasons:
1. After concrete placement, a survey is conducted for all critical pours to verify the final position of EPs and concrete levels.
2. This survey is essential to assess tolerances in alignment, level, pockets, bolts, etc., within the concrete structure.
3. Post-concrete surveys also examine areas of honeycombing, visually observe bulging, and assess the type of surface finish on the concrete.