EXERCISE-4: LEVELING USING AUTO LEVEL (LAB REPORT)
KEYWORDS: Auto level, staff, Fall and rise method, method of collimation, error adjustment
ABSTRACT:
This report contains a brief explanation for the laboratory exercise levelling using auto level. Before using auto level, we need to know
about errors and procedures to use it. This report contains procedure and calculation methods to safely use auto level.
1. INTRODUCTION: Station Point Back Fore Height of R.L.(m) Remarks
Sight Sight instrument
The level instrument is set up on a tripod and, depending on the type,
either roughly or accurately set to a levelled condition using foot screws
(levelling screws). The operator looks through the eyepiece of the 1 CP1 1.182 129.591 128.409 BM1
telescope while an assistant holds a tape measure or graduated staff 2 CP2 1.354 1.554 129.391 128.037
vertical at the point under measurement. The instrument and staff are 3 CP3 1.362 1.358 129.395 128.033
used to gather and/or transfer elevations (levels) during site surveys or 4 CP4 1.348 1.315 129.428 128.080
building construction. Measurement generally starts from a benchmark 5 CP5 1.401 1.388 129.441 128.040
with known height determined by a previous survey, or an arbitrary 6 CP6 1.436 1.379 129.498 128.062
point with an assumed height.
7 CP7 1.090 128.408
∑ 8.083 8.084
2. OBJECTIVE: Table 1
The main objective of this lab exercise is to carry out leveling operation
Arithmetical Check:
using Automatic level and familiarize with the operation of the
instrument.
∑BS -∑FS =∑Rise -∑Fall = Last R.L. - First R.L
3. THEORY:
ð 8.083 – 8.084 = 0.415-0.416 = 128.408.128.409
A typical optical level consists of a tripod, a bubble or circular level ð -0.001 = -0.001 = -0.001 (verified).
and a telescope with a magnifying glass, and it is generally used in
combination with a marked stadia rod. The crosshairs establish the Hence, the levelling is acceptable.
level point on a targeted area, with one long horizontal line marking
the horizontal plane, and the stadia marks allow for the calculation of
distances.an automatic level allow the user to make rough adjustments Table 2
by moving the level’s components until the bubble level or circular 6.2 Height of collimation method:
level is in alignment. Arithmetical Check:
∑BS -∑FS =∑Last R.L. - First R.L
3.1 Errors sources for an auto level:
Back Fore
Auto levels can be more prone to human error than their more Station Point Fall Rise R.L.(m) Remarks
sight sight
complex cousins.
1 CP1 1.182 128.409 BM1
2 CP2 1.354 1.554 0.372 128.037
4. Equipment needed: 3 CP3 1.362 1.358 0.004 128.033
4 CP4 1.348 1.315 0.047 128.080
Nikon/Leica Automatic level, staff 5 CP5 1.401 1.388 0.040 128.040
6 CP6 1.436 1.379 0.022 128.062
5. Procedure: 7 CP7 1.090 0.346 128.408
∑ 8.083 8.084 0.416 0.415
5.1 Setting up the instrument:
ð 8.083 – 8.084 = 128.408.128.409
• Setup and level the instrument. ð -0.001 = -0.001 (verified).
• Take the first reading (back sight) by putting staff on the known
RL (near GI lab) Hence, the levelling is acceptable.
• Carryout fly leveling operation and calculate RL of some fixed
features (Electric Poles and Markings on Ground) using two
methods given above. 7. Adjusted data (Error distribution):
• Take the last reading (foresight) and close on the same point near
GI lab. Correction = (128.408 – 128.409)/6
• Enter observations in the leveling field book by two methods
= -0.001/6
6. Observations and Calculations: = -0.00017 m
6.1 Rise and fall method:
Adjust Adjusted
Back Fore ment R.L
Station Point Fall Rise R.L.(m) Remarks
sight sight
1 CP1 1.182 128.409 +0.0000 128.409 BM1
2 CP2 1.354 1.554 0.372 128.037 +0.00017 128.037
3 CP3 1.362 1.358 0.004 128.033 +0.00034 128.033
4 CP4 1.348 1.315 0.047 128.080 +0.00051 128.081
5 CP5 1.401 1.388 0.040 128.040 +0.00068 128.041
6 CP6 1.436 1.379 0.022 128.062 +0.00085 128.063
7 CP7 1.090 0.346 128.408 +0.00102 128.409
∑ 8.083 8.084 0.416 0.415
Table 3: Rise and Fall method(adjusted)
Station Point Back Fore Height of R.L.(m) Adjust Adjusted Remarks
Sight Sight instrument ment R.L
1 CP1 1.182 129.591 128.409 +0.0000 128.409 BM1
2 CP2 1.354 1.554 129.391 128.037 +0.00017 128.037
3 CP3 1.362 1.358 129.395 128.033 +0.00034 128.033
4 CP4 1.348 1.315 129.428 128.080 +0.00051 128.081
5 CP5 1.401 1.388 129.441 128.040 +0.00068 128.041
6 CP6 1.436 1.379 129.498 128.062 +0.00085 128.063
7 CP7 1.090 128.408 +0.00102 128.409
∑ 8.083 8.084
Table 4: Height of collimation method(adjusted)
