Difficulties in Leveling
Leveling is a process of surveying which involves measuring the relative heights of different objects on or below the earth’s surface. While it is an important part of surveying, it can be difficult due to various ground conditions, natural formations, and structural parts that can interfere with the process. The surveyor and staff must be prepared to face these difficulties in order to effectively complete the job.
Methods to Overcome Difficulties
In order to overcome the difficulties encountered during leveling, there are some methods that can be used by the surveyor and staff. These methods can help to ensure that the survey is completed successfully and on time. These methods may include the use of special equipment, techniques, and strategies to accurately measure the undulations of the ground. Additionally, surveyors should be familiar with the local terrain and conditions in order to best anticipate any difficulties that may arise.
Different Situations Those Makes Leveling Difficult
Some situations making leveling difficult are:
- When the staff is close to the instrument
- Leveling across a large lake
- Leveling across a river
- Leveling a cross a solid wall
- Bench mark lies above line of collimation
- Leveling along steep slope
- Leveling across depression or rising ground
When the Staff is Close to the Instrument
HOW TO PLACE THE STAFF CLOSE TO THE INSTRUMENT
Sometimes it is necessary to place the staff very near to the instrument for leveling. This can cause the instrument to lose its focus and become blur, making it difficult to note down the exact staff reading.
SOLVING THE PROBLEM OF STAFF PLACEMENT
This problem can be solved by using white paper. Holding the staff vertical and slowly moving the white paper up and down in front of it, the paper edge can be observed through the telescope. The line of collimation should meet the edge of white paper, and the staff reading at that point should be noted.
Leveling Across a Large Lake
Fixing Pegs
In order to level across a large pond or lake, two pegs must be fixed at the banks of the pond. The top surface of the peg should be visible or coincide with the water surface.
Measuring the RL
Using a level, the Reduced Level (RL) measurement of the first peg point can be taken by taking a foresight (FS). It is then assumed that the RL of the second peg point is the same as the first peg point.
Taking the Back Sight Reading
The level is then shifted to the other bank side and a back sight (BS) reading is taken from the second peg point. This completes the leveling process across the pond.
Leveling Across a River
- Introduction to River Leveling
River leveling is a method used to measure the difference in water levels between two banks of a river. Unlike in ponds or lakes, water levels in a river are constantly changing, making it impossible to measure the levels of the two banks accurately. This is where reciprocal leveling comes in. - Understanding Reciprocal Leveling
Reciprocal leveling is a technique used to measure the true difference in water levels between two banks of a river. In this method, two pegs are fixed at two different banks and the relative level (RL) of the first peg is taken in the usual manner. Then, the RL of the second peg is measured by obtaining the true difference in levels between the two pegs. - Benefits of River Leveling
River leveling is a useful technique that helps to accurately measure the water levels at two banks of a river. This information can be used to aid in a variety of activities such as flood control, navigation, and irrigation. Additionally, river leveling can also be used to help determine the volume of water flow in a river.
Leveling Across a Solid Wall
How to Measure RL of Points on a Solid Wall
When leveling a solid wall, it is difficult to measure the RL of the points in that wall’s position. To address this issue, two pegs are driven on both sides of the wall, just touching the wall. To find the height of the instrument, it is important to focus on any bench mark or Champion point. After that, the staff reading on one side of the wall should be noted down. Using the staff, measure the height of the wall. This data can then be used to calculate the RL of every point. The same process should also be applied to the other side of the wall.
Benchmark lies Above Line of Collimation
How to Take Fore-sight Reading Using Level?
When the bench mark lies above the line of collimation, such as on the bottom of bridge girder, lower surface of culvert etc., the fore-sight reading of point A can be taken first using a level positioned at O.
Steps Involved in Taking Back-sight Reading
To take back-sight reading, the staff is held at the benchmark (under the girder) in inverted position from the girder. The back-sight reading is then noted from the inverted staff and it is noted with a negative sign along with the annotation “staff held inverted” in the remarks column.
Leveling Along Steep Slope
Resolving Challenges in Leveling Along Steep Slopes
Leveling along steep slopes in hilly regions can be challenging, as it can be difficult to obtain consistent back sight and foresight readings. To address this issue, a zigzag pattern of instrument positioning can be used. The back sight and foresight readings should be kept equal while positioning the instrument in the zigzag path. This method can be applied to both positive and negative steep slopes, and the reduced level (RL) of each point can then be calculated.
Leveling Across Depression or Rising Ground
Rising Ground
When leveling a high-rise ground, the instrument must not be kept at the peak position. Instead, the instrument should be fixed in a position such that the line of collimation passes through the apex point of the high-rise ground.
Depressed Ground
If a depressed ground is encountered while leveling, the instrument should be positioned at one side of the depression and the staff should be placed at the other side.
