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

1

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.

1

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.

1

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.

10

11

09

08

104810030960

093708920848

116211181072

Introduction to Leveling – Hydro Training 2009

Importance of balancing

1

2

3

0

BM

Distance X

1

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

1

2

3

0

1

2

3

0

BS FS

BM A

TP

Distance X1

Distance X1

_2 2

1

2

3

0

Distance X2

BS

Distance X2

FS_1 3

Difference in Elevation = -2 m

TP

Distance X3

Distance YUNBALANCED

Distance X3

Distance X3

1

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

1

2

3

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

1

2

3

0

1

2

3

0

10m 10m 20m20m

Introduction to Leveling – Hydro Training 2009

Paper Kukkamaki - Collimation Check

Kukkamaki

1

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

9

10

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