3. Types of Surveys in Civil Engineering

3.2. Land Surveiying

1. Purpose of Land Surveying

Land surveying plays an essential role in various aspects of civil engineering, construction, and property management. The primary purposes of land surveying include:

  1. Defining Property Boundaries: Land surveying is used to establish legal property boundaries and ensure accurate delineation of land ownership. This is crucial for resolving disputes over land ownership and maintaining property rights.
  2. Site Preparation for Construction: Surveying helps in determining the exact location, dimensions, and features of a property to ensure proper planning and design of infrastructure projects such as roads, buildings, and utilities.
  3. Mapping and Topography: Land surveys provide topographic maps, which include the physical features of a site, such as slopes, contours, bodies of water, and existing structures, aiding engineers and architects in design and planning.
  4. Subdivision and Development: Surveying is critical when dividing land into smaller parcels (subdivisions) for sale or development, ensuring that zoning regulations, easements, and other legal requirements are met.
  5. Legal and Environmental Compliance: Land surveys ensure that land development and use comply with local zoning laws, building codes, environmental regulations, and other legal requirements.

2. Types of Land Surveys

Land surveying encompasses several specialized types of surveys based on the needs of the project or land use. Some of the most common types of land surveys include:

  1. Boundary Survey

    • Purpose: To establish the exact boundaries of a property, including corners, lines, and borders.
    • Method: Boundary surveys typically use existing property records and monuments (such as survey markers) along with precise measurements to determine the property lines.
    • Applications: Essential for buying, selling, or transferring property, as well as resolving boundary disputes.

  2. Topographic Survey

    • Purpose: To determine the elevation and layout of the land's physical features.
    • Method: Surveyors collect data on natural features (like hills, valleys, trees, rivers) and man-made structures (such as roads, buildings, and utilities). They measure the terrain's contours and elevations.
    • Applications: Used for designing and planning infrastructure such as roads, drainage systems, and buildings by providing detailed maps of the land's features.

  3. Construction Survey

    • Purpose: To mark out the locations of buildings, roads, and utilities according to the design plans.
    • Method: Surveyors use precise measurements and control points to layout construction projects. This includes setting stakes or markers for foundations, roads, and utilities.
    • Applications: Critical during the construction phase to ensure that the project is built to the correct dimensions and locations.

  4. Subdivision Survey

    • Purpose: To divide a larger parcel of land into smaller plots for development or sale.
    • Method: Surveyors create a plan that shows how land is divided into smaller lots, taking into account local zoning regulations and infrastructure requirements.
    • Applications: Typically used for residential or commercial developments.

  5. ALTA/NSPS Land Title Survey

    • Purpose: A specialized land survey required by lenders, title companies, or real estate developers to ensure the legal boundaries of a property are properly established.
    • Method: It combines a boundary survey with detailed information about improvements on the land, easements, rights-of-way, and other title-related data.
    • Applications: Used in commercial real estate transactions, particularly when properties are bought, sold, or mortgaged.

  6. Geodetic Survey

    • Purpose: To measure the precise size and shape of the Earth, taking into account its curvature and other large-scale features.
    • Method: Geodetic surveys use advanced instruments like GPS and theodolites, and rely on mathematical models to measure vast areas of land.
    • Applications: Often used for mapping large territories, land parcels, or in the creation of national and regional reference systems.

3. Land Surveying Instruments

Land surveying requires specialized instruments for measuring distances, angles, and elevations accurately. Some of the key instruments used in land surveying include:

  1. Total Station

    • Purpose: To measure both horizontal and vertical angles and distances.
    • Description: Combines an electronic theodolite and electronic distance measurement (EDM) technology. It can record data electronically and send it directly to a computer or data collector.
    • Applications: Used in boundary surveys, construction surveys, and topographic mapping.

  2. Theodolite

    • Purpose: To measure horizontal and vertical angles with high precision.
    • Description: A classic instrument with an optical telescope, graduated scales, and a rotating base that allows the surveyor to measure angles.
    • Applications: Used for triangulation and angle measurement in boundary and construction surveys.

  3. GPS (Global Positioning System)

    • Purpose: To measure precise geographic locations and elevations.
    • Description: GPS devices use satellite signals to determine positions with high accuracy, down to a few centimeters for specialized equipment.
    • Applications: Used in large-scale surveys, geodetic surveys, and boundary determination in remote or expansive areas.

  4. Leveling Instrument (Optical or Automatic Level)

    • Purpose: To measure vertical heights or differences in elevation.
    • Description: A level instrument typically consists of a telescope and a spirit level, and is used with a leveling rod to determine elevation.
    • Applications: Used in topographic surveys, site preparation, and ensuring accurate elevation data for construction.

  5. Measuring Tape

    • Purpose: To measure short distances.
    • Description: A flexible or rigid tape, usually in lengths of 30 meters or 100 feet, used for basic measurement tasks.
    • Applications: Used in small-scale boundary and construction surveys, especially when other high-tech instruments are unnecessary.

4. Land Surveying Process

The land surveying process generally follows these key steps:

  1. Research and Pre-Survey Work

    • Surveyors gather information from legal property documents, previous surveys, and maps. Research includes reviewing deed descriptions, titles, and land records to ensure accuracy in measurements.

  2. Site Visit and Field Surveying

    • Surveyors visit the site to measure distances, angles, and elevations. They place control points (reference markers) at key locations and may use instruments like theodolites, total stations, or GPS devices to collect data.

  3. Data Processing and Error Checking

    • Once data is collected, it is processed for accuracy. Errors in measurements (due to instrument calibration or human error) are corrected using established methods, such as adjusting angles or distances.

  4. Map Creation and Reporting

    • After data is processed, surveyors create a final map or report detailing the land's boundaries, topography, and features. The map includes critical information like legal property lines, easements, and landmarks.

5. Applications of Land Surveying

  • Real Estate Development: Land surveys are essential for property transactions, land subdivision, and zoning compliance.
  • Construction: Accurate surveys are necessary to ensure buildings, roads, and infrastructure projects are built within the correct boundaries and elevations.
  • Environmental Studies: Land surveys are used to assess natural features, flood zones, and environmental impacts before development projects begin.
  • Legal Disputes: In cases of property disputes or boundary conflicts, land surveys provide legal evidence of property lines and ownership.