What is the purpose of balancing a traverse?

Short Answer:

The purpose of balancing a traverse is to correct small errors that occur during field measurements so that the survey accurately forms a closed figure. In a closed traverse, the total of measured latitudes and departures should be zero. If not, adjustments are needed to “balance” the errors.

Balancing ensures that all angles and distances match up properly, leading to correct positions of points. This is important for creating accurate maps, boundary layouts, and construction planning. Without balancing, the final results may contain mistakes and cannot be trusted for engineering work.

Detailed Explanation:

Purpose of balancing a traverse

Traverse surveying involves measuring a series of connected lines and angles to determine the relative position of points. In practice, even with good instruments and careful work, small errors can occur due to instrument faults, environmental effects, or human mistakes. These errors can prevent the traverse from properly closing. The process of correcting these errors is known as balancing the traverse.

When a traverse is “closed,” it means the survey either returns to the starting point or ends at another known point. In such cases, the sum of all measured angles and the sum of calculated coordinates (latitudes and departures) must follow known geometric rules. But due to measurement errors, there is often a small difference, called the closing error.

Balancing a traverse is done to adjust the observed values so that the total measurements form a perfect closed figure. This makes the final drawing or plotted layout accurate and usable for civil engineering purposes.

Reasons for balancing a traverse:

  1. To remove closing error: Balancing corrects the difference between the starting and ending point that results from small measurement mistakes.
  2. To ensure accurate coordinates: The corrected values help compute true coordinates of each point, which are important for drawing plans and calculating areas.
  3. To improve the reliability of data: Adjusted data gives confidence that the layout or design based on the survey is trustworthy.
  4. To prepare error-free maps: Without balancing, maps can be distorted, and layouts may have overlapping or missing areas.
  5. To meet engineering standards: Construction, road design, and boundary markings require precise surveys, and balancing ensures those requirements are met.

How balancing is done:

Balancing involves mathematical methods to spread the closing error across all measured lines. Two common methods are:

  • Bowditch Rule: Distributes errors based on the length of each line. Best used when both angle and distance measurements are equally accurate.
  • Transit Rule: Distributes errors based on the size of the latitude and departure. Best used when angles are more reliable than distances.

After balancing, the corrected latitudes and departures are used to compute exact coordinates. These can then be used to plot the traverse on paper or into a computer for CAD or GIS applications.

Balancing is usually done for closed traverses, where errors can be detected and corrected. In an open traverse, such checking is not possible because there’s no known endpoint for comparison.

Conclusion

The purpose of balancing a traverse is to correct small measurement errors so that the survey forms a perfect closed shape. This ensures accurate plotting, reliable coordinates, and professional survey results needed for construction and boundary work.