Collecting original ground levels is a critical task in land surveying that establishes the foundation for accurate engineering designs and construction projects. Accurate ground level data ensures that structures such as roads, buildings, and drainage systems are designed with respect to the existing terrain. Survey professionals in Kenya rely on precise instruments and well-maintained equipment to capture these levels effectively, accounting for the diverse topography found across the country. This chapter examines the essential tools, equipment, and materials used in the collection of ground levels, highlighting their specifications, uses, and care within professional surveying practice.

2.1 Tools, equipment and materials

The process of collecting original ground levels depends on a combination of specialized tools and materials that enable surveyors to measure vertical distances accurately and record data systematically. In Kenya's land surveying industry, the selection and maintenance of these instruments directly influence the quality and reliability of survey results. This section provides detailed descriptions of the primary equipment used, focusing on their specifications and operational roles in field surveys.

2.1.1 Level and Tripod with Oral stand

The level is the core instrument for determining height differences by establishing a horizontal line of sight. Automatic levels are preferred in Kenyan surveys due to their self-leveling mechanisms, which reduce human error and speed up fieldwork. The tripod must be robust, stable on uneven ground, and allow precise height adjustments to position the level instrument securely. The oral stand supports the levelling staff vertically at the point being measured, ensuring accurate readings without the need for manual holding, which can introduce errors.

Proper setup involves securely fixing the tripod legs on firm ground, mounting the level, and calibrating the instrument to ensure the horizontal crosshair aligns perfectly. Regular maintenance includes cleaning lenses, checking bubble vials, and lubricating moving parts to maintain precision.

2.1.2 Levelling staff

The levelling staff is a graduated rod that enables surveyors to measure the vertical distance from the instrument’s line of sight to the ground. Commonly made from lightweight aluminium, it allows easy transportation and durability in the field. The staff features clear graduations typically marked in millimetres and centimetres for precise readings.

Staffs may be graduated in single or double scales, with some models telescoping for compact storage. When reading the staff, surveyors must ensure it is held plumb, either manually or with an oral stand, to avoid systematic errors. In practice, a staff is essential for projects ranging from setting foundation levels at a county hospital construction site to road grading in rural areas.

2.1.3 Tape

Steel tapes are preferred for their durability and minimal stretch, which ensures consistent measurement of horizontal distances. Lengths of 30m or 50m are common in Kenyan surveying to cover a wide range of site dimensions. The tape is marked with clear metric graduations to facilitate precise readings.

Use involves anchoring one end at a fixed point while extending the tape to the target point. The tape must be kept taut and level to avoid sagging, which can cause measurement errors. After use, the tape should be cleaned and coiled carefully to prevent kinks or corrosion, which degrade accuracy over time.

2.1.4 Ranging rod

Ranging rods serve as visual markers that assist surveyors in lining up points and establishing straight survey lines during traversing or levelling. Their bright alternating colours increase visibility over long distances, which is crucial when working in open fields or hilly terrain.

2.1.5 Booking sheet

The booking sheet is a standardized form used to record field measurements systematically during levelling operations. It ensures data is captured legibly and consistently, facilitating error checking and later processing.

Purpose of the Booking Sheet

• Provides a clear record of all height readings and calculations in the field.
• Ensures data consistency across survey teams by standardizing entries.
• Facilitates quick identification of errors or anomalies during data transcription.
• Acts as an official document for audit and verification by client institutions such as the Ministry of Lands.
• Supports efficient data transfer to office software for further analysis and map production.

Layout and Essential Fields

• Columns for station names or codes to identify survey points.
• Fields for back sight, fore sight, and intermediate sight readings.
• Space for reduced levels and remarks.
• Date and surveyor’s signature for accountability.
• Notes section for field conditions or observations affecting measurements.

Best Practices in Usage

• Fill the sheet immediately after each reading to avoid memory lapses.
• Use legible handwriting and avoid overwriting to maintain clarity.
• Double-check entries in the field before moving to the next station.
• Retain the original sheets securely as they are legal survey records.
• Use carbon copies or digital forms where possible to prevent data loss.

2.1.6 Pen/pencil

Writing instruments are vital for recording measurements and annotations on booking sheets and sketch maps. Surveyors often prefer pencils for fieldwork due to their erasability and resistance to smudging in humid conditions.

Types of Writing Instruments

• Mechanical pencils with fine leads for precise, clear markings.
• Ballpoint pens for permanent records where erasure is not desired.
• Waterproof ink pens for writing on coated or laminated sheets.
• Standard HB pencils for general note-taking.
• Marker pens for making visible marks on ranging rods or pegs.

Selection Criteria

• Durability under field conditions, including rain and dust.
• Ease of use with gloves or in cold weather.
• Compatibility with the type of paper or material being written on.
• Availability and cost-effectiveness for prolonged survey campaigns.
• Ability to produce clear, legible, and consistent markings.

Handling and Maintenance

• Keep pencils sharpened to maintain legibility.
• Store pens capped to prevent drying out.
• Replace worn-out leads or cartridges promptly.
• Carry spare writing instruments to avoid disruption.
• Avoid using ink pens on rough or wet surfaces to prevent smudging.

2.1.7 Eraser

Erasers are essential for correcting mistakes on booking sheets and sketch maps during fieldwork. They help maintain data accuracy and neatness, which are critical for later interpretation.

Types of Erasers

• Rubber erasers suited for graphite pencil marks.
• Vinyl erasers that remove ink marks cleanly.
• Kneaded erasers useful for delicate corrections without damaging paper.
• Mechanical erasers attached to pencils for convenience.
• Portable erasers designed for field conditions.

Correct Use in Surveying

• Erase only errors clearly identified to avoid accidental data loss.
• Erase gently to prevent tearing or smudging of paper.
• Use erasers compatible with the writing instrument to avoid paper damage.
• Inspect the corrected area to ensure no residual marks remain.
• Dispose of eraser debris promptly to keep the workspace clean.

Maintenance and Storage

• Keep erasers clean and free from dust or grit.
• Store in protective cases to prevent deformation.
• Replace erasers that become too small or hardened.
• Avoid exposure to excessive heat which can harden rubber.
• Carry backups during field assignments.

2.1.8 Calculator

In Kenya, surveyors at institutions like county governments rely on calculators to process field data on site, speeding up decision-making processes. Regular maintenance includes battery replacement and keeping the device clean to ensure reliable operation.

2.1.9 Pegs

Pegs are used to mark fixed points on the ground where measurements have been taken. They provide visible reference points for future surveys or construction activities. Wooden pegs, often painted with bright colours for visibility, are commonly used in Kenyan fieldwork.

Proper placement ensures stability and prevents displacement by wind, animals, or human activity. Pegs may be inscribed with station codes or other identifiers to facilitate recognition.

2.1.10 Mallet

A mallet is essential for driving pegs into hard or compacted ground, ensuring they remain fixed during the survey period. The wooden construction reduces damage to pegs compared to metal hammers.

Surveyors working in rocky or clay soils, such as those around Nakuru, require mallets to anchor markers securely. Careful use avoids bending or breaking pegs, preserving the integrity of survey reference points.

2.1.11 Marker pen

Marker pens are used to write station codes, measurements, or other pertinent information on pegs, rods, and booking sheets. Permanent, waterproof ink ensures markings remain visible despite exposure to weather.

In practice, marker pens help survey teams at agricultural cooperatives distinguish boundary points clearly during land demarcation exercises. Different tip sizes allow for flexibility in marking large or small surfaces.

2.1.12 Panga

In forested or overgrown areas such as parts of Western Kenya, the panga facilitates access and safety. Proper handling and maintenance, including regular sharpening and safe storage, are essential to prevent accidents and ensure longevity.

Chapter Summary

This chapter examined the essential tools, equipment, and materials required for collecting original ground levels, including the level and tripod with an oral stand, levelling staff, tape, ranging rod, booking sheet, pen or pencil, eraser, calculator, pegs, mallet, marker pen, and panga. It emphasized the importance of accurately identifying existing control points as a foundation for reliable surveying. The process of taking ground levels was detailed, highlighting the techniques and careful measurements needed to ensure precision. Additionally, the chapter covered the systematic booking of ground levels, where observations are recorded clearly and methodically for further analysis. Understanding the proper use and maintenance of the tools contributes to efficient and accurate surveying work. The integration of these components ensures that surveyors can establish baseline elevations necessary for engineering projects and construction planning. Mastery of these fundamentals supports the overall quality and reliability of survey data.