How to Calculate HI (Hight of the instrument) and mark levels using Auto level machine?

Step-by-Step Guide to Calculating HI and Marking Levels

Tags: #construction #landsurveyor

In this tutorial, we'll explain how to calculate the Height of Instrument (HI) and mark levels accurately using a total station.

Step-by-Step Process

1. Identify the Benchmark (BM): Start by determining the elevation of your benchmark. For example, let’s assume the BM elevation is 46.509.
2. Take the Backsight (BS) Reading: Using your total station, measure the BS. For example, the BS reading is 1.59.
3. Calculate the Height of Instrument (HI): Add the BM elevation to the BS reading:
   • HI = BM + BS
   • HI = 46.509 + 1.59 = 48.099
4. Save the HI: To save this value, enter it into your total station. For example:
   • Press SHIFT and then STORE.
   • Save the value under an alpha key (e.g., A).
5. Determine the Target Level: Subtract the desired level from the HI:
   • Stop Reading = HI - Target Level
   • Stop Reading = 48.099 - 47.9 = 0.199
6. Adjust for Marking: If the stop reading is hard to mark, adjust it by adding a value for convenience. For example:
   • Add 0.5 to make the stop reading 0.7.
7. Mark the Point: Using the adjusted stop reading, mark the level at the desired location.

Final Tips

Always double-check your calculations and instrument settings to ensure accurate results. Consistent practice will help you master level marking with a total station.