Levelling Survey
| Site: | Shule Yetu Bora |
| Course: | Shule Yetu Bora |
| Book: | Levelling Survey |
| Printed by: | |
| Date: | Wednesday, 4 June 2025, 11:03 PM |
Description
By the end of this module the learner should be able to operate levelling instruments such as dumpy levels, auto levels, and digital levels, record field measurements (backsight, foresight, and intermediate sight), and apply various levelling methods, including differential, profile, and reciprocal levelling. The course covers practical applications in construction, roadworks, drainage, and land development, emphasizing accuracy, error minimization, and compliance with industry standards.
1. Introduction to levelling survey
Levelling is a branch of surveying that determines the relative height of different points on, above, or below the earth's surface. It helps establish elevation differences for construction and engineering projects.
Purpose:
- Establishing grades for roads and buildings
- Determining drainage patterns
- Creating topographical maps
2. Types of levelling
a) Direct Levelling (Spirit Levelling):
- Uses a level instrument and a graduated staff.
- Most common method.
- Highly accurate.
b) Barometric Levelling:
- Utilizes atmospheric pressure differences.
- Less accurate, suitable for exploratory work.
c) Trigonometric Levelling:
- Based on trigonometric calculations using angles and distances.
- Used in large-scale mapping and remote areas.
d) Stadia Levelling:
- Uses a tacheometer.
- Combines horizontal distance and vertical height measurements.
e) Differential Levelling:
Measures elevation difference between two points using backsight and foresight readings