What is Plane Table Surveying?

Introduction

What is Plane Table Surveying?

Plane table surveying is a versatile and precise land surveying technique that has been used for centuries. It involves the use of a simple yet powerful tool: the plane table. This method allows surveyors to create accurate maps and plans directly in the field, making it an invaluable asset in various industries, including construction, agriculture, and urban planning.

Getting Started with Plane Table Surveying

What Are the Essential Tools?

Before embarking on a plane table surveying expedition, you’ll need a few essential tools:

• Plane Table: This is the centerpiece of the operation, typically a flat wooden or metal surface where you’ll sketch your observations.
• Alidade: A sighting device attached to the plane table that helps you measure angles.
• Tripod: To secure the plane table in a stable position.
• Measuring Instruments: Ranging rods, chains, or tapes for measuring distances.

Setting Up Your Plane Table

1. Place the plane table securely on the tripod.
2. Level the table using a spirit level.
3. Orient the table by sighting a known point or using a magnetic compass.

The Art of Plane Table Surveying

How Does It Work?

Plane table surveying relies on the principle of visual triangulation. Surveyors observe distant objects or landmarks from their position and record the angles between them. By measuring these angles, along with distances, they can create accurate maps and plans.

Best Ways to Use a Plane Table

• Choose clear days with good visibility for accurate sightings.
• Keep your equipment clean and well-maintained.
• Use a sketching technique that suits your preferences, whether it’s the “fixed orientation” or “free orientation” method.

Benefits of Plane Table Surveying

Why Choose Plane Table Surveying?

1. Real-time Results: Plane table surveying allows you to see the map develop as you work, providing immediate feedback.
2. High Accuracy: When done correctly, this method offers exceptional precision.
3. Cost-Effective: It requires minimal equipment and can be used in remote areas.

What are the 4 types of plane table surveying?

Plane table surveying is a technique used in land surveying to create maps and plans directly in the field using a plane table as the primary instrument. There are various methods or types of plane table surveying, each suited to different situations and objectives. Here are four common types:

1. Radiation Method (Intersection Method):

   • In this method, the plane table is set up at a known reference point.
   • The surveyor sights and measures angles to prominent features or objects (usually three or more) from the station.
   • These angles are marked on the paper attached to the plane table.
   • The lines representing these angles intersect at the point on the map where the survey station is located.
   • This method is suitable for mapping small areas with well-defined landmarks.

2. Traversing Method (Resection Method):

   • The traversing method is used when no reference points are visible from the survey station.
   • The surveyor first measures a reference direction (azimuth) using a compass or theodolite.
   • Then, angles are measured to selected objects or points around the station.
   • These angles are marked on the paper, and lines are drawn from the station along the measured angles.
   • The intersection of these lines determines the position of the station.
   • This method is suitable for areas with limited visibility of distant points.

3. Intersection Method:

   • In the intersection method, two known points are selected, and angles are measured to various features or objects from both stations.
   • The angles are marked on the paper at each station.
   • Lines are drawn from each station along the measured angles.
   • The intersection of these lines provides the locations of the observed objects.
   • This method is useful for mapping features that are not visible from a single station.

4. Trilateration Method:

   • Trilateration is used when measuring distances between survey points is essential.
   • Known reference points (control points) are used, and distances to these points are measured using a chain, tape, or electronic distance measurement (EDM) instrument.
   • Distances and angles to observed points are measured, and these measurements are used to calculate the positions of the observed points.
   • Trilateration allows for accurate positioning of points over a wide area and is suitable for large-scale surveys.

Each of these types of plane table surveying methods has its advantages and limitations, and the choice of method depends on factors such as the size of the area to be surveyed, the availability of reference points, and the survey objectives. Surveyors select the most appropriate method to ensure accurate and reliable results for a specific project.

Step-by-Step Guide to Plane Table Surveying

Preparing the Fieldwork

1. Choose your survey area and objectives.
2. Set up the plane table as described earlier.
3. Select your alidade and measuring instruments.

Executing the Survey

1. Identify and mark reference points.
2. Sight these points from your position and record the angles.
3. Measure distances using your chosen instruments.

Recording Data

1. Sketch the observed points, angles, and distances on the plane table.
2. Compile this information into a cohesive map or plan.

Common Challenges in Plane Table Surveying

Overcoming Errors

• Ensure proper leveling and orientation of the plane table.
• Double-check your measurements and calculations.
• Account for atmospheric refraction and instrument errors.

Dealing with Environmental Factors

• Be aware of weather conditions that could affect visibility.
• Adjust for magnetic declination if necessary.

Tips for Achieving Precision

Maintaining Accuracy

• Practice sighting techniques to reduce errors.
• Calibrate your instruments regularly.
• Collaborate with a team for cross-verification.

Avoiding Common Mistakes

• Don’t rush the survey; accuracy takes time.
• Keep detailed records of your work.
• Continuously update your skills.

Do’s and Don’ts in Plane Table Surveying

What You Should and Shouldn’t Do

Do:

• Prioritize safety during fieldwork.
• Choose the right scale for your map.
• Verify the accuracy of your measurements.

Don’t:

• Neglect instrument maintenance.
• Disregard environmental factors.
• Skip the calibration process.

What are the uses of plane table?

A plane table is a versatile tool used in land surveying and cartography for a variety of purposes. Its primary function is to create maps and plans directly in the field. Here are some of the key uses of a plane table:

1. Topographic Mapping: Plane tables are commonly used for creating topographic maps, which represent the contours and features of the land’s surface. Surveyors can sketch the terrain, including hills, valleys, rivers, and other natural and man-made features, with precision.

2. Land Parcel Surveys: Plane tables are useful for conducting land parcel surveys, especially in rural and undeveloped areas. Surveyors can accurately define property boundaries and record the positions of landmarks, such as property corners and boundary markers.

3. Construction Layout: Construction professionals use plane tables to lay out the positions of structures, roads, utilities, and other elements on construction sites. This helps ensure that buildings and infrastructure are placed accurately according to the design plans.

4. Engineering Surveys: In civil engineering projects, plane tables are employed to create detailed surveys of project sites. This includes recording elevation data, measurements, and other critical information needed for engineering design and analysis.

5. Resource Management: Plane table surveys are valuable for assessing and managing natural resources, such as forests, wetlands, and agricultural land. They enable accurate mapping of resource boundaries and conditions.

6. Environmental Studies: Environmental scientists use plane tables to map ecological features, including vegetation types, wildlife habitats, and soil characteristics. These surveys aid in environmental impact assessments and conservation efforts.

7. Urban Planning: Plane tables play a role in urban planning by helping city planners and architects create base maps of urban areas. These maps are used for designing infrastructure, zoning, and land use plans.

8. Archaeological Surveys: Archaeologists use plane tables to document archaeological sites, including the positions of artifacts, excavation units, and site boundaries. This information is critical for research and preservation.

9. Geological Surveys: Geologists utilize plane tables to create geological maps that show rock formations, fault lines, and geological features. These maps are essential for studying Earth’s subsurface and geological history.

10. Disaster Management: Plane tables can be used in disaster management and emergency response to map affected areas, assess damage, and plan relief efforts. They are valuable tools for quickly generating accurate field data.

11. Educational Purposes: Plane tables are often used in surveying and cartography education to teach students the principles of mapping, angle measurement, and data collection in a hands-on manner.

12. Boundary Disputes: In legal cases involving boundary disputes or property ownership, plane tables can be employed to create accurate surveys and visual representations of boundaries.

13. Site Analysis: Architects and landscape architects use plane tables for site analysis, helping them understand the existing conditions and constraints of a site before designing structures or landscapes.

In summary, plane tables are versatile instruments used in various fields, including land surveying, engineering, environmental science, and urban planning. They enable accurate data collection, mapping, and visualization of geographic and spatial information, making them valuable tools for professionals across diverse industries.

Why is a plane table survey important?

A plane table survey is important for several reasons, as it offers numerous advantages and benefits in the field of land surveying and cartography. Here are key reasons why a plane table survey is considered important:

1. Real-time Mapping: Plane table surveys allow for the creation of maps and plans directly in the field. This real-time mapping capability is invaluable for visualizing and documenting the features of the surveyed area immediately during data collection.

2. High Precision: When conducted correctly, plane table surveys can achieve a high level of precision and accuracy in mapping land features, boundaries, and topography. This precision is crucial for various applications, including construction, engineering, and property assessment.

3. Immediate Feedback: Surveyors can observe the progress of the map as it develops on the plane table. This immediate feedback helps identify errors, inconsistencies, or missing data, allowing for on-the-spot corrections and improved data quality.

4. Cost-Effective: Plane table surveys are cost-effective compared to some other surveying methods, especially for smaller-scale projects. They require relatively simple equipment and can be conducted with minimal manpower, reducing overall project costs.

5. Simplicity and Versatility: Plane table surveys are straightforward to conduct and do not require complex instruments. They can be used in a wide range of environments, from remote rural areas to urban settings.

6. Suitability for Small Areas: Plane table surveys are particularly well-suited for mapping smaller areas or specific sites, such as individual land parcels, archaeological sites, and construction sites. They are effective for tasks that don’t require large-scale survey equipment.

7. Immediate Visualization: The surveyor can immediately visualize the landscape and features on the plane table, which aids in decision-making, design, and planning processes. It also facilitates effective communication with stakeholders.

8. Hands-On Learning: Plane table surveys are valuable for educational purposes, as they provide hands-on experience for students and professionals learning about land surveying, cartography, and geographic information systems (GIS).

9. Historical Documentation: Plane table surveys have been used for centuries and have contributed to the historical documentation of land use, property boundaries, and geographical features. Historical plane table maps offer insights into past landscapes.

10. Local Knowledge: Plane table surveys often involve surveyors physically engaging with the terrain. This hands-on approach allows them to gain local knowledge about the area, which can be valuable for understanding land characteristics and conditions.

11. Emergency Response: In emergency situations, such as natural disasters, plane table surveys can quickly provide updated maps and data for disaster response teams, helping them assess damage and plan relief efforts.

12. Boundary Disputes: In legal cases involving property boundaries and land disputes, plane table surveys can provide accurate and defensible evidence of property lines and boundaries.

In summary, a plane table survey is important due to its ability to provide real-time, precise, and cost-effective mapping solutions, making it a valuable tool for land surveyors, engineers, architects, environmental scientists, and various professionals who rely on accurate spatial data. It offers a practical and versatile approach to mapping that has stood the test of time and continues to be relevant in various applications.

Frequently Asked Questions (FAQs)

What is the history of plane table surveying?

Plane table surveying dates back to ancient civilizations and has evolved with technological advancements. It remains a valuable method in modern surveying.

Can I use plane table surveying for small-scale projects?

Absolutely. Plane table surveying is versatile and suitable for projects of all sizes.

How long does it take to become proficient in plane table surveying?

Becoming proficient depends on your dedication and practice. With consistent effort, you can master it in a few months.

Conclusion

In conclusion, plane table surveying is a powerful tool that empowers surveyors to create accurate maps and plans with precision and efficiency. By following the best practices outlined in this guide, you can harness the full potential of this technique for your land surveying needs. Remember, practice makes perfect, so embark on your surveying journeys with confidence and curiosity.