Engineering Surveying Study Notes

INTRODUCTION TO ENGINEERING SURVEYING

Course Overview

  • This course is structured into five (5) lectures:

    • Lecture 1: Introduction to engineering surveying

    • Lecture 2: Methods for setting out engineering projects

    • Lecture 3: Computation of areas and volumes for earthworks

    • Lecture 4: Mass-haul curves

    • Lecture 5: Setting out of curves

Lecture Overview

  • The lecture explores fundamental aspects of engineering surveying, including:

    • Definition of engineering surveying

    • Purpose of engineering surveying

    • Principles of engineering surveying

    • Engineering surveying procedures

    • Plan scales

    • Coordinate systems

    • Positioning techniques

    • Errors in surveying

Learning Outcomes

  • Upon completion of this lecture, students should be able to:

    • Define engineering surveying and elucidate its scope within engineering practice.

    • Describe the purpose and significance of engineering surveying in engineering projects.

    • Explain the fundamental principles underpinning engineering surveying.

    • Identify and outline typical engineering surveying procedures employed in practice.

    • Relate engineering surveying activities to stages of planning, design, construction, and maintenance of engineering works.

Lecture Objectives

  • The lecture aims to:

    • Introduce students to the concept and scope of engineering surveying.

    • Explain the purpose and significance of engineering surveying in engineering projects.

    • Discuss the fundamental principles governing engineering surveying practice.

    • Familiarize students with conventional engineering surveying procedures and workflows.

    • Establish foundational knowledge for topics in engineering surveying to follow.

ENGINEERING SURVEYING DEFINED

Definition

  • Engineering Surveying: The branch of surveying that utilizes measurement and mapping techniques to support planning, design, construction, and maintenance of engineering projects by providing accurate spatial data and setting out engineering works on the ground.

  • It is a generalized term for all survey work associated with civil engineering and building projects.

  • Engineers and surveyors conducting site surveys are accountable for all dimensions and controls regarding these projects.

Key Points on Engineering Surveying

  • Supports engineering design and construction.

  • Provides precise horizontal and vertical control.

  • Involves measurement, analysis, and setting out.

  • Critical for the success of engineering projects.

Activities According to FIG

  • Engineering surveying encompasses activities that include:

    • Acquisition, processing, and management of topographic and related information throughout a project's lifecycle.

    • Setting out methods in engineering projects.

    • Validation and quality control for civil construction and manufacturing.

    • Deformation prediction, monitoring, analysis, and interpretation.

WHY ENGINEERING SURVEYING

Necessity

  • In engineering and the built environment, surveys are essential for planning, constructing, and maintaining:

    • Highways and railroads.

    • Buildings and construction.

    • Irrigation systems.

    • Water and sewerage systems.

    • Mining and mineral exploration.

PURPOSE OF ENGINEERING SURVEYING

Key Purposes

  1. Concept and Design Stage:

    • Provide large-scale topographical surveys and measurements crucial to the project's design. Precision at this stage is vital as design reliability hinges on the executed works.

  2. Construction Stage:

    • Offer precise controls for positioning works, ensuring engineering projects align correctly concerning relative and absolute positions (setting out).

  3. Post-Construction Stage:

    • Monitor structural movement on major retaining structures through deformation measurements.

    • These activities are predicated on horizontal and vertical control frameworks that consist of fixed points known as control stations.

BASIC ENGINEERING SURVEYING PRINCIPLES

Fundamental Principles

  1. Principle of Working from Whole to Part:

    • Establish major control points prior to conducting detailed measurements.

  2. Principle of Control:

    • All engineering surveys must reference well-defined horizontal and vertical control points.

  3. Principle of Error Management:

    • Errors should be minimized, detected, and adjusted through appropriate procedures and checks.

  4. Principle of Consistency and Verification:

    • Survey measurements must be independently verified to ensure reliability. Higher-order networks allow looser standards in lower orders without compromising overall accuracy.

  5. Principle of Accuracy and Precision:

    • Measurements must achieve accuracy suitable for the engineering task.

    • Accuracy: Difference between true value and estimated value (often unknown).

    • Precision: Measurement spread; an observation can be consistent (precise) but inaccurate.

  6. Principle of Economy:

    • Conduct engineering surveying efficiently, achieving necessary accuracy and reliability without excessive expenditure of resources.

  7. Principle of Redundancy:

    • Surveys should include extra observations beyond the minimum necessary to detect, check, and reduce errors.

  8. Safety and Ethical Principles:

    • Safety is paramount, especially in public spaces or construction sites. Ethical practices ensure honest reporting of measurements and data.

ENGINEERING SURVEYING PROCEDURES

Six Steps in Engineering Surveying

  1. Preparation and Planning:

    • Analyze project requirements, maps, and drawings. Determine survey type and methods; prepare instruments, personnel, and safety measures.

  2. Reconnaissance (Preliminary Survey):

    • Site visit to assess terrain, obstacles, and access; identify measurement features; refine the survey plan; prepare a reconnaissance diagram, marking stations, and beaconing.

  3. Fieldwork (Measurement):

    • Establish control points and benchmarks; conduct precise distance, angle, and elevation measurements; execute topographic, cadastral, or construction layout surveys.

  4. Reduction and Adjustment of Observations:

    • Process raw data, correct systematic and random errors, compute coordinates, elevations, and alignments. The methods of adjustment must be agreed upon and applied consistently.

  5. Plotting / Drawing:

    • Generate maps and plans highlighting contours, features, and layout lines. Use appropriate scales for observations, executing plots either manually or by computer-aided design (CAD).

  6. Preparation of Report:

    • Document measurements, calculations, and observations; include notes, recommendations, and verified data. Submit for design, construction, or record-keeping purposes. The survey report should capture:

      • Personnel involved

      • Equipment utilized

      • Methods of surveys and computations

      • Final survey diagram (completed reconnaissance diagram)

      • Results (coordinates of all points)

      • information beneficial for other nearby parties.

RECAP - GE 161 BASIC SURVEYING PRINCIPLES

Key Topics Reviewed

  • Fundamentals such as:

    • Temporal adjustment of theodolites and levels.

    • Distance and angular measurements.

    • Traverse computations and adjustments.

    • Spirit leveling.

    • Introduction to triangulation, trilateration, resection, intersection, and radiation.

    • Field booking and checks.

    • Sources of error and corrections.

  • Utilization of basic surveying equipment:

    • Tape.

    • Leveling instruments.

    • Theodolites.

    • Stadia tachymetry.

  • Surveying Tasks:

    • Leveling and contouring.

    • Detail survey.

    • Traversing.

RECAP - POSITIONING TECHNIQUES

Positioning Methods

  1. Linear Measurements:

    • Offsets

    • Trilateration

  2. Angular Measurements:

    • Triangulation

    • Intersection

  3. Comprehensive Measurement Techniques:

    • Traversing

    • Polar coordinates

    • Resection

Satellite Positioning (GPS)

  • A relatively recent system that aids navigation and positioning globally, providing 3D coordinates simultaneously based on electromagnetic signals from a constellation of 24 satellites in precise orbits.

  • GPS positioning involves:

    • Signal reception at ground stations by GPS receivers, measuring the precise time the signals are received.

    • Resection from satellites, calculating distances using radio signal travel time.

    • Accurate positioning requires error corrections.

Map Scales

Definition

  • A map scale represents the ratio between a distance on a map and its corresponding distance on the ground, indicating how the area has been reduced on the map.

Importance

  • Map scale is crucial for interpreting maps, both physical and digital.

  • Categories of map scales vary from large-scale maps (1:10,000) to small-scale atlases (1:1,000,000).

Types of Map Scales

  • Verbal Scales.

  • Representative Fraction Scales.

  • Graphical Scales.

Examples of Map Scales

  • Typical UK scales:

    • 1:1250: Basic urban plans.

    • 1:2500: Basic rural plans.

    • 1:25000: General country mapping.

  • Typical Ghanaian scales:

    • 1:2500: Urban plans.

    • 1:50000: Rural plans.

CLASSIFICATION OF MAP SCALES

By Scale

  1. Large Scale Maps:

    • Cover less area, show more details, minimal generalization, extensive textual information.

  2. Small Scale Maps:

    • Cover more area, show fewer details, more generalization, and limited textual information.

  3. In Ghana:

    • Large scale (<1:5000) for town sheets.

    • Medium scale (<1:50,000) for topographic maps.

    • Small scale (>1:50,000) used in atlas maps.

CLASSIFICATION OF MAP SCALES BY FUNCTION

General Reference Maps

  • Aim to display the locations of all features on Earth, showcasing many geographic features like roads, coastlines, and political boundaries.

  • An example: Topographic maps depict both natural and artificial features of areas covered, including boundaries.

Special Purpose or Thematic Maps

  • Display distributions of singular attributes or relationships among several attributes, emphasizing spatial patterns relative to specific themes.

REFERENCE SYSTEMS

Positioning and Heights

  • Positions reference a coordinate system, heights refer to a vertical datum, and directions reference a bearing.

Types of Directions

  1. True North:

    • Points to the Earth’s rotation axis determined by astronomical observations.

  2. Grid North:

    • Subject to projections.

  3. Magnetic North:

    • Based on compass readings, easier to obtain but not accurate.

COORDINATE SYSTEMS

  • Categories include:

    • Grid System

    • Polar System

    • Geographic System

Heights

  1. Absolute Height:

    • Referred to a datum level surface, typically Mean Sea Level (MSL).

  2. Relative Height:

    • Difference in height between surveyed points, providing arbitrary values.

RECAP – ERRORS IN SURVEYING

Sources of Error

  1. Natural Sources:

    • Weather, refraction, gravity.

  2. Instrumental Sources:

    • Imperfect construction and adjustment.

  3. Personal Sources:

    • Human inability to make precise observations.

  4. Types of Errors:

    • Blunders (Gross Errors): Resulting from mistakes by persons or equipment.

    • Systematic Errors: Follow mathematical or physical laws and can be adjusted.

    • Random Errors: Unintentional and can be identified and corrected through statistical processes.

LECTURE SUMMARY

  • This lecture establishes the principles of engineering surveying, highlighting its role in supporting the planning, design, construction, and maintenance of engineering projects, along with outlining the fundamental principles and typical procedures relevant to engineering surveying.