A method of surveying that establishes a series of connected survey stations by measuring distances and angles between consecutive points.

Traverse

Definition

A traverse is a fundamental surveying method that establishes a connected series of survey stations through the measurement of distances and angles between consecutive points. This technique forms the backbone of many surveying operations and is essential for creating accurate maps, establishing property boundaries, and planning infrastructure projects.

Types of Traverses

Closed Traverse

A closed traverse begins at a known point and returns to the same point, or connects between two known points. This type provides built-in error checking, as surveyors can compare the calculated position with the actual starting position. Closed traverses are preferred in professional surveying because they allow for error detection and correction through closure calculations.

Open Traverse

An open traverse starts at a known point but does not return to a known point or connect to another known point. While open traverses are sometimes used for reconnaissance work or linear projects like road surveys, they lack the ability to detect and correct systematic errors, making them less desirable for precise work.

Equipment and Measurements

Traverse surveying requires accurate measurement of two key components: distances and angles. Modern surveyors use total stations, theodolites, and transit instruments to measure horizontal and vertical angles with precision. Distances are measured using tape measures, electronic distance measurement (EDM) equipment, or integrated into total station devices.

Procedure

The standard traverse procedure involves:

1. Establishing stations: Marking survey points at regular intervals along the traverse line 2. Measuring distances: Recording horizontal distances between consecutive stations 3. Measuring angles: Recording horizontal and vertical angles at each station 4. Recording data: Documenting all measurements with field notes 5. Calculating coordinates: Computing the position of each station using trigonometry 6. Checking closure: Verifying that measurements are within acceptable error tolerances

Error Analysis and Closure

In closed traverses, the surveyor calculates how much the computed endpoint differs from the known endpoint. This difference is called the closure error. Acceptable closure depends on the survey specifications, typically ranging from 1:5,000 to 1:20,000 of the total traverse length for engineering surveys.

Errors are distributed throughout the traverse using methods such as the Bowditch method (proportional to distance) or the transit method (proportional to latitude and departure components).

Applications

Traverse surveying is used for:

Property surveys: Establishing boundary lines and land divisions

Engineering projects: Creating baselines for construction and infrastructure

Topographic surveys: Establishing control networks for mapping terrain

Route surveying: Surveying roads, railroads, and pipeline routes

Municipal surveys: Mapping city boundaries and utility locations

Advantages and Limitations

Traverses are economical and flexible, adapting well to terrain constraints and following natural or constructed features. However, they accumulate errors over long distances and require careful fieldwork to maintain accuracy. Modern GPS and satellite-based positioning now often supplements or replaces traditional traverse methods, though traverse surveying remains fundamental to many surveying applications.

Modern Developments

Contemporary traverse surveying integrates digital instruments, data collectors, and processing software that automate calculations and reduce human error. Integration with GPS/GNSS systems provides quality control and can supplement traditional angle and distance measurements.