Intro to Leveling
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Transcript of Intro to Leveling
Introduction to Leveling – Hydro Training 2009
Intro to Leveling
Leveling
Introduction to Leveling – Hydro Training 2009
• To determine elevation with respect to an imaginary level surface (geoid)
• Leveling allows you to tie the depths acquired with the sonar to the geoid
Why do we level?
Introduction to Leveling – Hydro Training 2009
Leveling
Introduction to Leveling – Hydro Training 2009
Equipment
Level – An instrument used for measuring vertical distances
Introduction to Leveling – Hydro Training 2009
Compensated level
Introduction to Leveling – Hydro Training 2009
Level rod
A long brightly painted rod, accurately calibrated in metric units (or feet and inches), used for obtaining elevations and stadia measurements of distance in mapping with a major surveying instrument.
Introduction to Leveling – Hydro Training 2009
Leveling terminology
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2
3
0
1
2
3
0
BM A BM B
Backsight - reading on a rod that is held on a point whose elevation has been previously determined
Foresight - reading on a rod that is held at a point whose elevation is to be determined
Introduction to Leveling – Hydro Training 2009
Leveling terminology cont.
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2
3
0
1
2
3
0
BM A
BM B
Turning point - a temporary point whose elevation is determined by additions and subtractions of backsights and foresights respectively.
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2
3
0
Introduction to Leveling – Hydro Training 2009
Leveling terminology cont.
Bust – Error is outside of tolerance for comparison of the forward run to the backward run
Blunder – Gross error caused by human mistake
Thread Interval- Difference between upper thread and middle thread, lower thread and middle thread
Thread error- Inaccurate reading of rod resulting in greater than 2mm difference between thread interval
Introduction to Leveling – Hydro Training 2009
SAMPLE ROD READING
TOP THREAD = MIDDLE THREAD = BOTTOM THREAD =
Note: Tread interval from top to middle = 45 and middle to bottom = 43. Ideally, the thread intervals should be equal, however this seldom occurs in the field. Thread intervals for 3rd order levels should match within 2 therefore, this would be an acceptable reading.
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11
09
08
104810030960
093708920848
116211181072
Introduction to Leveling – Hydro Training 2009
Importance of balancing
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0
BM
Distance X
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2
3
0
BM
Distance Y
Distance X
3 – 3 = 0
Introduction to Leveling – Hydro Training 2009
Bird’s eye view of a standard level run
+3
+2+5
-4+2
+5-5
-2+4
-5
-2-3
SPUR
SPUR
Forward RunBackward Run
Introduction to Leveling – Hydro Training 2009
Forward RunBackward Run
Bird’s eye view of a “RAINIER” level run
+3
+2+5
-4+2
+5-5
-2+4
-5
-2-3
SPUR
SPUR
Introduction to Leveling – Hydro Training 2009
Sample Level Run
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0
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0
BS FS
BM A
TP
Distance X1
Distance X1
_2 2
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3
0
Distance X2
BS
Distance X2
FS_1 3
Difference in Elevation = -2 m
TP
Distance X3
Distance YUNBALANCED
Distance X3
Distance X3
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2
3
0
BS FS_2 1
Difference in Elevation = +1 m
BM B
What is the difference in elevation between BM A and BM B?The difference in elevation = 0 + (-2) + 1 = -1 m
BM B is 1 m below BM A
Introduction to Leveling – Hydro Training 2009
Error
Introduction to Leveling – Hydro Training 2009
Parallax
Introduction to Leveling – Hydro Training 2009
Collimation
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0
Collimation – the accuracy of the alignment of the optics of the level. Poor collimation will result in gross errors and possibly a bust.
Introduction to Leveling – Hydro Training 2009
Allow instruments to acclimate to
ambient temperature for at least 10 minutes!!
Kukkamaki setup
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10m 10m 20m20m
Introduction to Leveling – Hydro Training 2009
Paper Kukkamaki - Collimation Check
Kukkamaki
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3rd 1
10 m 10 m
ROD 1 ROD 2SET UP 1
BS 1 FS 1
ROD 1 ROD 2
20 m20 m
SET UP 2
BS 2 FS 2
KUKKAMAKI COURSE & SET UPS
= Differenceh = HeightBS = BacksightFS = ForesightC = Collimation Error
Instrument SN: Rod SN: Party Chief: Observer: Recorder: Rod Person:
C = ( h1 - h2 ) - 0.2 mm 20 m
BS1 - FS1 = h1BS2 - FS2 = h2where
sum 3
mmBS1
2
sum 3
mmBS2
sum 3
mmFS1
sum 3
mmFS2
Introduction to Leveling – Hydro Training 2009
2 1929
No 9 196
Kahului 161 5680 1 1
11/24/98
1
2
172416541583
4961 mm162815531480
4661 mm9622 mm
7071
7573
141 mm
+ 148 mm289 mm
1653.7
+ 1553.7
3207.4 mm
162015481477
4645 mm164915691490
4708 mm+ +9353 mmBS FS
BS - FS = 9.622 m- 9.353 m
0.269 m 3
0.08966 m
1548.3
+ 1569.3
3117.6 mm
3.2074 m- 3.1176 m
0.08980 m
check
7271
8079
143 mm
+ 159 mm302 mm
0.289 m + 0.302 m 0.591 m x 333196.803 m 1000 0.196 km
Stadia
Difference < 30
Difference < 2
Tip for Quick Mean
1) Sum all thread readings in BS column.2) Sum all thread readings in FS column.3) BS - FS4) Divide by 35) Convert to meters
DE Computation
Distance Computation
1) Sum all THREAD INTERVALS.2) Multiply by the Instruments Stadia.3) Convert to Km.
0.0897 m- 0.0907 m 0.0010 m 0.20 km
Always use smallest distance
- (FORWARD RUN + BACKWARD RUN)
1 = + 0.3 mm2 = + 0.7 mm
Top Interval > Bottom Interval, then add to Middle HairTop Interval < Bottom Interval, then subtract from Middle Hair
:
Introduction to Leveling – Hydro Training 2009
1692161215324836 mm1562148914174468 mm1664165916534976 mm
14280.0 mm
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11
+
+
1668159215184778 mm1612154214714625 mm1722171617115149 mm
+
+ 14552.0 mm
BS - FS = 14.280 m - 14.552 m 0.272 m 3- 0.09067 m
1612.0 mm
+ 1489.3 mm
+ 1658.7 mm
4760.0 mm
1592.7 mm
+ 1541.7 mm
+ 1716.3 mm
4850.7 mm
4.7600- 4.8507- 0.0907 m
check
8080
7372
56
160 mm
+ 145 mm
+ 11 mm 316 mm
7674
7071
65
150 mm
+ 141 mm
+ 11 mm 302 mm
0.316 m + 0.302 m 0.618 m x 333205.784 m 1000 0.205 km
Stadia
Introduction to Leveling – Hydro Training 2009
Newiz
Paper leveling made easy!
Introduction to Leveling – Hydro Training 2009
Run