Surveying 2 - Taking a level reading - OTEN Building & Construction

Summary

In the video, Dave, the OTEN Head Teacher, demonstrates level measurement techniques at Nirimba College. He introduces a five-stage aluminum staff, explaining its color-coded sections for extension verification. Dave highlights the importance of using a fiberglass staff near power cables for safety. He discusses the 'E pattern' graduation and the necessity of reading to the millimeter for accuracy. The process of taking a level reading is detailed, including ensuring the staff's cleanliness, holding it vertically, and interpreting the reading to three decimal places. The video concludes with a preview of a two-peg test for level accuracy.

Takeaways

• 🏫 The video is set at Nirimba College and features an OTEN Head Teacher, Dave, who is demonstrating surveying techniques.
• 👷‍♂️ Dave introduces a two-man process for taking readings using a levelling instrument, which is a common practice on construction sites.
• 🔍 The staff used is a five-stage aluminum staff, designed for durability and ease of use in surveying.
• 🔑 The staff has color-coded sections (black and red) to help the surveyor ensure that all sections are properly extended.
• ⚠️ Safety is emphasized with the mention of using a fiberglass staff near overhead power cables to avoid electrical hazards.
• 📏 The staff is graduated in an 'E pattern' and is used in conjunction with a measuring tape graduated to millimetres for precise measurements.
• 📐 Readings are taken to three decimal places, indicating a high level of accuracy required in surveying work.
• 🧐 The necessity of interpolating readings within 10-millimetre graduations on the staff is explained, requiring estimation skills.
• 👋 Proper staff handling techniques are demonstrated, including keeping the staff clean and holding it in a way that allows clear visibility of the graduations.
• 🔄 The importance of moving the staff vertically to ensure the most accurate reading is highlighted, as tilting can affect the reading.
• 📋 The video concludes with a reading of 1.372 metres, demonstrating how to locate this measurement on the staff.

Q & A

What is the purpose of the staff shown in the video?

The staff is used in conjunction with a level instrument to take accurate measurements, particularly for leveling tasks on construction sites.

How many sections does the staff have?

The staff is a five-stage staff, meaning it has five sections.

Why is the staff color-coded?

The staff is color-coded with alternating colors to help the person looking through the instrument identify which sections have been extended.

What material is the staff made of and why is it important?

The staff is made of aluminum, but for work near overhead power cables, a fiberglass staff is recommended to avoid electrical conductivity.

What does the 'E pattern' graduation on the staff signify?

The 'E pattern' graduation refers to the way the staff is marked with measurements, which is typically used in building sites for precise measurements.

Why is it necessary to read levels to three decimal places?

Reading levels to three decimal places, or to the millimeter, ensures the accuracy of measurements on site, which is crucial for construction activities.

How does the measuring tape help in taking readings from the staff?

The measuring tape, graduated to millimeters, is used to interpolate and estimate readings between the 10-millimeter graduations on the staff.

What are the three things to ensure when holding the staff for a reading?

When holding the staff, one must ensure the bottom is clean for an accurate reading, keep hands clear of the graduations for visibility, and wave the staff to find the vertical position for the lowest reading.

Why is it important to wave the staff during the reading process?

Waving the staff helps the person taking the reading to identify the lowest point, which corresponds to the vertical position, ensuring the most accurate measurement.

What is the reading obtained in the video and how is it located on the staff?

The reading obtained is 1.372 meters, which is located on the staff at the 1.37 meter mark, plus an additional two millimeters.

What is the next step after taking a reading that the video mentions?

The next step mentioned is to complete a two-peg test to verify the accuracy of the level's readings.