As with most construction or DIY projects, certain precautions and procedures need to be assessed and implemented to ensure a successful result. Levelling is a process that involves determining the height of one level in relation to another. Without the proper knowledge or equipment, some errors may occur and result in inaccurate measurements, increasing the risk of user error and project cost. Here are the most common levelling mistakes that both beginners and even professional surveyors make and how they can be avoided.
1. The Level is set-up incorrectly
In some cases, lack of knowledge or care means that an instrument won’t be set-up correctly. If one is rushing on a job, or has not been taught the appropriate techniques, the instrument will not perform to the best of its ability and will deliver unreliable results. This can be costly for any project, both with time and money, as more often than not, if measurements are wrong, the process will have to be repeated. It is always worth taking your time or checking with an expert for correct methods.
Ways to eliminate incorrect set-ups include:
• Ensuring that the tripod is pushed into the ground with the legs spaced apart from each other. This will create a sturdy, stable support system. Once the tripod is ready, adjust the head to make a flat surface for the level to rest on.
• Test and adjust the instrument. Calibrating the level will ensure your results are accurate. With an Optical Level, check that the bubble axis is in the centre and properly focus the eye-piece. With a Laser Level, auto-level it then rotate the instrument by 180 degrees and reshoot the point. This will increase the accuracy by manually averaging the observations of each face.
2. The staff isn’t held vertically or it is misread
When levelling, a staff must always be held vertically in order to ensure that the most accurate results. Levelling staffs are also prone to damage, so care must be taken so they’re in the best possible condition for your readings. Not only should time be taken when reading the staff to avoid a misreading, surveyors should also follow these simple steps:
• Attach a Digital Laser Detector, this lets a user know whether the staff is vertical.
• Check how vertical the staff is by standing it to the side of a vertical line and observing alignment.
• Hold both hands down the side of the staff whilst standing completely upright.
• Record the lowest reading after rocking it back and forth.
3. The environment isn’t taken into account
Temperature, terrain and other atmospheric conditions. When preparing to level, these environmental factors need to be considered. They can throw off your readings and once again leave a user with inaccurate measurements. It is important to inspect the work site and take the necessary precautions to avoid these factors affecting your end results.
These errors include:
• The sun. When there is bright sunlight where you’re levelling, it can become incredibly difficult to take a precise reading. If you can shield the work area, it may be possible to continue without difficulty. However, it is recommended that surveyors invest in a green beam laser – these are 400% more perceptible to the eye than red beam lasers.
• The wind. A powerful wind may disturb your instrument and the verticality of the staff. In these conditions, it is imperative that the level, staff and tripod be consistently tested and aligned. However, owing to the loss of time on a project, it is advised that the work is delayed until it passes.
• The temperature. Extreme temperatures or fluctuations in temperature may disturb the instrument, causing errors in staff readings and unreliable refractions of the intervening medium. Minimise these effects by letting the instrument rest in a steady atmosphere, or invest in a robust laser level that can withstand these intense temperatures.
If you feel prepared to take on your next levelling project, check out our comprehensive levelling range here. For accessories that help ensure you receive the most accurate results possible, click here.