auto level survey

An auto level survey, also known as differential leveling or automatic leveling, is a surveying method used to determine the difference in elevation between two points on the Earth's surface. It's commonly used in civil engineering, construction, and land surveying for various purposes such as establishing grade lines, determining heights of structures, and creating topographic maps. Here's a general overview of how an auto level survey is conducted: 1. **Setup**: The surveyor sets up the auto level instrument on a tripod at a known or arbitrary elevation point, called a benchmark. 2. **Calibration**: The auto level instrument is calibrated to ensure its accuracy. This typically involves checking and adjusting the bubble level and focusing the telescope. 3. **Backsight Reading**: The surveyor looks through the telescope and sights a leveling rod held at a benchmark or known elevation point. The rod is typically marked with graduations representing elevation units (such as feet or meters). 4. **Record Backsight Reading**: The surveyor records the reading on the leveling rod where the crosshairs of the telescope intersect. This reading represents the elevation of the benchmark. 5. **Move to Next Point**: The surveyor moves the auto level instrument to the next location where an elevation is to be determined. This location is typically within line of sight of the benchmark. 6. **Fore-sight Reading**: The surveyor looks through the telescope and sights the leveling rod held at the new location. The rod reading is recorded when the crosshairs intersect with it. 7. **Calculate Elevation Difference**: The difference between the backsight reading (elevation of benchmark) and the foresight reading (elevation of the new point) is calculated. This difference represents the change in elevation between the two points. 8. **Repeat**: The process is repeated for additional points as needed to create a profile or contour map of the surveyed area. 9. **Check Levels**: Throughout the survey, the surveyor periodically checks and adjusts the instrument to ensure it remains level and accurate. 10. **Data Recording**: All measurements and relevant data are recorded in a field book or digital surveying software for later analysis and interpretation. Auto level surveys provide accurate elevation data, allowing engineers and planners to make informed decisions about grading, drainage, and construction projects. They are particularly useful for projects that require precise leveling over relatively large distances.