12.11. Total Station Survey Procedures – Step-by-Step Field Methodology

Visit the site to identify control points, line-of-sight, and obstructions. Establish a survey control network or use existing geodetic control stations. Plan data collection route, number of stations, and data types.

Before starting a Total Station survey, it's important to conduct reconnaissance. This involves visiting the survey site to identify crucial details such as control points that will anchor your measurements, assess the line-of-sight for clear visibility, and identify any obstructions that could interfere with your measurements. You also need to establish a control network, which can involve placing permanent markers or relying on existing geodetic control points. Finally, you should plan your data collection route, which includes deciding how many stations you will set up and what specific types of data you will collect.

Think of reconnaissance and planning like preparing for a road trip. Before you hit the road, you’d want to check your route for traffic jams (obstructions), know where your stops (control points) are, and decide how often you want to refuel (data collection stations). This preparation ensures that your trip goes smoothly and efficiently.

Fix permanent control markers (e.g., concrete pillars, pegs). Record initial coordinates, or set using GPS or previous survey data.

Establishing control points is a critical step in conducting a Total Station survey. After identifying your control points during reconnaissance, the next step is to fix these points securely, often using materials like concrete pillars or survey pegs. These markers will serve as reference points for all measurements taken throughout the survey. It's also essential to record the initial coordinates of these control points, which can be set using GPS technology or based on data from previous surveys to ensure accuracy.

Imagine planting flags in the ground during a treasure hunt. Each flag represents a point you will measure from; they need to be secure so that as you navigate toward each one, you can trust they haven’t moved. Similarly, control points provide stable reference locations for your survey measurements.

Place and level the Total Station over a control point. Perform instrument orientation using known coordinates or resection.

The setup of the Total Station is crucial to ensure that measurements are accurate. First, you’ll place the Total Station directly over a control point you’ve established. It's essential to level the instrument precisely to eliminate any tilt, which can lead to measurement errors. After leveling, you will need to orient the Total Station using known coordinates or a method called resection, which aligns the instrument to existing locations in the survey.

Setting up the Total Station can be compared to setting the compass before hiking. Just as you would ensure your compass is level and calibrated before beginning your hike to navigate correctly, the Total Station must be set up accurately to guide your measurements.

Use standard coding for topographic features (trees, walls, drains). Collect data in auto-mode or manual prism mode based on terrain. For detail points, record offset distances, object types, and notes.

When you begin the data collection phase, it’s important to use a standard coding system to efficiently classify and identify different topographic features such as trees, walls, and drains. Depending on the terrain's characteristics, you can collect data using either an automatic mode, which streamlines the process, or a manual prism mode for more control. For detailed points, it’s crucial to note offset distances from the control point, the types of objects observed, and any additional notes to provide context for the data collected.

Think of data collection like writing down a shopping list while at the grocery store. You categorize items (topographic features) into sections, decide whether to use the self-checkout (auto-mode) or traditional checkout (manual mode), and take notes on sales or special items so you can remember them later.

Perform repeat measurements for verification. Check prism constants, atmospheric settings, and zero errors.

To ensure the accuracy of your survey, conducting daily field checks is vital. This involves taking repeat measurements of the same points to verify consistency and reliability. You'll also check important settings within the Total Station, such as prism constants (which can vary by conditions), atmospheric settings (to account for changes in conditions), and zero errors (which checks if the instrument is correctly zeroed out). Regular checks evade potential errors in your overall data collection.

Consider daily field checks like a quality control check in a bakery. Just as bakers may frequently taste their products to ensure they’re consistent in quality and flavor, surveyors regularly verify their measurements to validate their results.

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