Recommendation points
- The essence and specifics of leveling
- Determination of benchmark and key points
- Installation and alignment of the sight
- Leveling staff designations
- How to measure point elevation
- Logging and calculations
An optical level is considered by many to be archaism, while it is one of the most accurate instruments in the framework of geodetic research. In our review, we will satisfy the interest of ordinary people on the use of a level for the geometric method of constructing planes.
Two surveyors at different edges of the abyss:
Level (shouts): Go!
Reika: Chtooo?
Level (even louder): Go!!!
Reika: I can’t hear!!!
Levelier (mutters): Deaf idiot…
Reika (shouts): Himself an idiot!!!
The essence and specifics of leveling
There are many ways to determine the curvature of the earth’s surface: by the slightest difference in atmospheric pressure, using a theodolite or a water level and other devices. However, geometric leveling is considered the most versatile, fastest and most accurate method: even technical levels used in construction have a measurement error of only 10 mm per km.
The essence of leveling is to determine the height difference (elevation) of each of the set of points on the terrain relative to a certain reference point, which is called a benchmark in construction. After the virtual plane has been determined, the zero mark is measured relative to it, which in most cases lies at the level of the floor of the first floor of the building..
In principle, there is nothing difficult in leveling except for two specific points. On the one hand, a surveyor with a partner must be able to use a level and a staff, know the subtleties of setting and correctly install control posts. Another nuance lies in the fact that there may be objects on the ground that prevent visual contact between the level and the staff. Therefore, the installation site of the level has to be periodically relocated, determining the time benchmarks and setting the height difference for them. But in the end, all calculations come down to commonplace arithmetic..
Determination of benchmark and key points
In a geodetic survey of a construction site, the benchmark is placed at the lowest point of the plane, which is determined visually or by a cursory “lumbago”. In this place, a massive pillar with a straight cut is driven into the ground, on which it is convenient to install a rail.
The number and location of key points depends on the leveling tasks. When it comes to preparing a foundation pit, the points are placed on the inner and outer corners along the contour of the future structure. When placing control points, high accuracy is not required, it is only important that there are no local bumps or pits at the location of the stakes.
Within the boundaries of the settlement there are special, measured and officially approved, reference points for reference to them when measuring new construction sites.
All points should be as equidistant as possible from the installation site of the level and be at least 5 meters away from it. If a small area is leveled, you can shoot all points from the side with a level, or use the hydrostatic level.
Installation and alignment of the sight
First you need to set up a tripod. Having loosened the screws for fastening the telescopic legs, the tripod must be aligned so that the upper platform lies in the horizontal plane, here everything is done “by eye”. The legs need to be pressed into the loose soil, pressing the foot against the stop, while the distance between them should be the same. Adjust the height of the legs so that the tripod head is at chest level, then tighten the screws.
When the tripod is installed, the level itself is attached to it by means of a central screw. It has two platforms: the lower one is fixed to the tripod with a screw or in another standard way, the upper one rests on three adjusting screws. On the sides of the triangle formed by the screws, there are three cylindrical presetting vials. By rotating one pair of screws, you first need to ensure that the bubble between them is exactly between the marks. After that, by twisting the third screw, two other levels are set. The fine adjustment indicator – a circular level – is located on the optical tube of the level. It may be necessary to turn the adjusting screws a little to get the bubble exactly within the circular mark. The level is ready to work.
Leveling staff designations
Before you start shooting the area, it would be nice to figure out how to navigate the rail. Indeed, what are these incomprehensible letters “E”, what are the black and red marks? In reality, everything is very simple..
The strip is divided into segments, each 10 cm long. Inside each segment there are black and white areas, each one is 1 cm long. The outer three black areas are united by a side line – this is to make it easier to visually determine the center of the segment. The numbers indicate in which ten centimeters the segment marks are located, that is, in fact, the position on the rail is determined by the number of white and black sections added to the number of ten.
But the accuracy of one centimeter is clearly not enough. The fact is that on the back side of the rail there is a usual millimeter graduation, which is not very convenient to use at long distances. Therefore, the assistant holding the rail can additionally adjust the slider, guided by the surveyor’s commands “above” and “below”, and then show the number of millimeters on his fingers. Also, some levels are equipped with a metric grid, according to which this deviation is even easier to determine..
Finally, the most interesting question: why the top of the rail has red markings in reverse order. The fact is that the old levels did not have an additional lens and the surveyor saw the image upside down. But you hardly have to deal with such “dinosaurs”.
How to measure point elevation
Before shooting the point, the assistant should place the staff as close to the control peg as possible, gently supporting it on the adjacent ground. During measurements, the staff must be kept motionless and strictly vertical, using a plumb line or a round bubble level for alignment.
The level must be turned towards the rail so that the vertical axis of the grid is located exactly in its center. After that, by turning the optical screw, you need to adjust the image sharpness so that the marks on the staff are clearly visible. Then you need to adjust the sharpness of the grid display by rotating the ring on the eyepiece.
To determine the excess, it is necessary to mark the number of the segment on which the vertical axis is located, and then calculate how many whole black and white intervals from the beginning of the segment to the axis. By adding this value after the segment number, you get the elevation in centimeters. If you need higher precision, a comma is put after the elevation, then the assistant moves the slider so that its edge exactly coincides with the horizontal axis and transfers the number of additional millimeters, which is written after the decimal point.
You can do without a slider. If the horizontal axis is located exactly in the middle of the white or black mark, add three millimeters, if in the lower quarter – one or two, if in the upper quarter – four. This visual definition is more than enough for construction..
Logging and calculations
The leveling process involves maintaining a large number of records. The surveyor should have at hand a site plan, which schematically shows the object for the construction of which leveling is performed, as well as the location of the control stakes. Each peg must be numbered and these designations must be placed in a separate table, in which the measured excess is noted.
Now about the excess itself. They are relative and absolute, that is, from the plane of measurement of the level and from the benchmark. For example, the excess of the reference point was 145.2 cm, and the control point – 151 cm. Subtracting the excess of the point from the excess of the reference point, we find that the absolute excess will be -4.8 cm, while the minus sign makes it clear that the current is located below. Similar calculations should be performed for each of the points.
The practical meaning of leveling is to mark the stakes in the same horizontal plane. To do this, you need to find the highest point with the largest positive excess value and add to it, for example, 20 cm.Following from one peg to another, they use a tape measure to postpone the value of the point excess to which the offset value is added – the same 20 cm. The received marks are used when conducting earthworks and determining the depth of the excavation, or for pulling the mooring cord.
Could you please provide step-by-step instructions on how to effectively utilize a level and rail during construction projects?
To effectively utilize a level and rail during construction projects, follow these step-by-step instructions:
1. Start by setting up the rail, which serves as a guide for maintaining a level surface. Lay the rail on the ground or fix it horizontally against a wall, depending on the project requirements.
2. Position the level on top of the rail, making sure it is securely attached or balanced on the rail. The level will help you determine if the rail or surface is perfectly horizontal or vertical.
3. Adjust the position of the rail if it is not level. Use shims or supports to lift or lower specific areas, ensuring the rail is perfectly leveled. Double-check the level with the help of a bubble or digital readings to confirm its accuracy.
4. Once you have successfully leveled the rail, it is ready to be utilized as a reference or guide. For example, if building a wall, you can place the bottom edge of the brick or block against the rail to maintain a consistent height or level. This will result in a straight and professional-looking construction.
5. Continuously check the level throughout the construction process to make sure it remains accurate. Adjust the rail or make necessary adjustments as needed to maintain the desired level.
By following these step-by-step instructions, you can effectively utilize a level and rail during construction projects to ensure precision, accuracy, and a professional outcome.
I would like to know if anyone can explain step-by-step how to effectively use a level and rail during construction. What are some key tips or techniques to ensure accurate measurements and proper alignment? Any advice on different types of levels or rails to use for specific projects would be highly appreciated. Thank you in advance for sharing your knowledge!
To effectively use a level and rail during construction, follow these steps:
1. Start by selecting the appropriate level for your project. Choose between a standard bubble level or a laser level, depending on your needs.
2. Ensure that your level is clean and in good condition before beginning.
3. Place the rail on the surface you want to check for level or aligning.
4. If using a bubble level, position it on the rail and adjust until the bubble is centered between the markers. For a laser level, turn it on and align the laser beam with the desired line or point.
5. Double-check your level by moving it along the rail or surface and repeating the bubble or laser adjustments if needed.
6. Take accurate measurements by marking the points where the level indicates alignment, and use these marks as reference throughout your project.
7. For proper alignment, adjust the rail or surface until the level consistently indicates a level position or desired alignment.
8. Use clamps or supports to secure the rail or surface in place once you have achieved the correct alignment.
9. Regularly check the level throughout your project to ensure the accuracy is maintained.
Remember, practice and experience will refine your skills in effectively using a level and rail.