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1.15. Example 1.33: Length and Bearing of Missing Traverse Leg
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Today, we're going to look at the closure of traverses, which is essential for keeping our surveying accurate. What do you think happens if we miss a leg in our traverse?
We might not be able to calculate the exact position of points accurately.
Exactly! That's why we perform calculations to find missing legs. For instance, we set up equations for the sum of latitudes and departures. Can anyone explain what latitudes and departures are?
Latitudes refer to the east-west distances, while departures are the north-south distances.
Great! Now, can someone summarize how we apply these concepts to find a missing leg?
We create equations based on the given lengths and bearings to find the miss leg's values.
Correct! Remember to maintain closure—it's crucial for accuracy. We will build upon this in our next session.
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Let's dive into calculating the length and bearing of our missing leg, BC. What should we first do with the given latitudes and departures?
We need to set up our equations based on the existing values to solve for L and θ.
Exactly! Let’s write down the closure equations for latitude and departure. Can anyone help me out with what those equations would look like?
The sum of latitudes should equal zero, right? So L cos θ would need to close with the other latitude sums.
Yes! And the same goes for departures. Once you solve these, you can calculate θ using trigonometry, right?
Yes! We can find θ by dividing the departure equation by the latitude equation.
Great thinking! Let's wrap this up with a summary of our method.
To find the missing leg, we set up closure equations and solve for L and θ.
Perfect! Keep this method in mind as it will be useful for future problems.
Overview
Short Summary
This section outlines the methods for determining the length and bearing of a missing leg in a traverse based on existing data.
Medium Summary
The section discusses the process of calculating the missing traverse leg length and bearing using trigonometric principles, illustrated through a practical example. It emphasizes the relationships between latitudes, departures, and the importance of maintaining closure in traverse calculations.
Detailed Summary
In this section, we focus on determining the length and bearing of a missing traverse leg (BC) in a closed traverse where certain data points are given, specifically the lengths and angles of surrounding traverse lines. Using trigonometric equations and the principle of closure in traversing, we establish relationships among the latitude and departure of the given lines. The closure of latitudes and departures plays a crucial role in accurately calculating the necessary parameters for the missing leg. The section illustrates how angles and distances can be computed to ensure the accuracy of surveying work, which is fundamental for any civil engineering project.
Key concepts
Core takeaways and short definitions to help you quickly recall the key ideas from this section.
- Traverse Closure:
The principle that coordinates for a closed traverse must sum to zero.
- Latitude & Departure:
Fundamental components for calculating distances in field surveying.
- Angle Calculation:
Using trigonometry to determine missing angles from known data.
- Cosine & Sine Functions:
Basic trigonometric functions essential for resolving traverse calculations.
Examples
Step-by-step examples to apply the section's ideas and test your understanding.
Example of a closed traverse with existing lengths and bearings; calculating the missing leg involves setting up equations for both latitude and departure.
Trigonometric resolution to find angles when the distance is known between points in a traverse.
Memory aids
Imagine a surveyor walking a square. They start at a point, make a complete loop, and need to return to the starting point without error; this is traverse closure.
Think 'LDB'—Latitude, Departure, Bearing for remembering the key components of a traverse.
Flash Cards
Glossary
Traverse
A survey process used to map a series of linear measurements and angles between points; assists in determining areas and volumes.
Latitude
The distance measured along the east-west direction in a survey, typically represented in coordinate systems.
Departure
The distance measured along the north-south direction; important for closing traverses.
Bearing
The direction of a line segment described in degrees or angles in a traverse.