Tablet Survey

Overview

Tablet survey, also known as plane table surveying, is a traditional field surveying method that allows surveyors to plot data directly onto paper in the field rather than in an office. This method has been used for centuries and remains valuable for certain applications despite modern technological advances.

Equipment and Components

The primary instrument in tablet surveying is the plane table, a flat wooden or metal board mounted on a tripod. The main accessories include:

Alidade: A straightedge with sights used for observing distant points

Trough compass: For orientation purposes

Spirit level: To ensure the plane table remains horizontal

Drawing paper: Mounted on the plane table surface

Measuring chain or tape: For distance measurements

Methodology

The tablet survey process begins with setting up the plane table on a tripod at a known station point. The table must be carefully leveled and oriented using the compass. The surveyor then plots the station point on the paper and proceeds to observe surrounding features.

Using the alidade, the surveyor sights distant objects and draws lines toward them on the paper. By measuring actual distances in the field and scaling them appropriately on the paper, the surveyor creates a map simultaneously with field observations. This immediate visual feedback allows surveyors to identify gaps in coverage and adjust their approach accordingly.

Advantages

Tablet surveying offers several notable benefits:

Immediate visualization: Maps are created in real-time, allowing surveyors to see results and identify missing data

Cost-effective: Requires minimal equipment compared to modern electronic instruments

Independence: Doesn't rely on electrical power or batteries

Intuitive method: Results are visible immediately, making communication with clients easier

Suitable for small areas: Works well for detailed surveys of limited regions

Limitations

Despite its advantages, tablet surveying has significant constraints:

Weather dependent: Rain, wind, and strong sunlight can damage paper and affect accuracy

Limited accuracy: Generally less precise than modern electronic methods

Time-consuming: Plotting data manually is slower than digital collection

Skill-dependent: Requires experienced personnel for accurate results

Unsuitable for large areas: Inefficient for surveying extensive territories

Modern Applications

While largely replaced by GPS, total stations, and GIS technologies, tablet surveying still finds use in:

Archaeological surveys

Quick reconnaissance surveys

Environmental field studies

Educational demonstrations

Areas with limited technological access

Historical Significance

Tablet surveying played a crucial role in mapping large portions of the world before modern surveying instruments were developed. Many historical maps were created using this method, and it remains an important part of surveying heritage and history.

Conclusion

Although tablet surveying has been superseded by digital technologies in most professional surveying, it remains a valuable technique for specific applications and serves as an important educational tool for understanding fundamental surveying principles. Its simplicity and independence from technology make it relevant even in contemporary surveying practice.