a closed traverse to measure heights at 5libvolume4.xyz/.../reductionoflevellingtutorial1.pdf ·...

Leveling

Rise & Fall Method

A closed traverse to measure heights at 5.0m intervals is to be taken through the center of a large

residential block. There are two existing structures on site that will obscure the view to some of the

positions.

STEP 1

Set up the instrument where the benchmark can be viewed within correct parameters and a reasonable

number of sights can be viewed. This location is identified as L1.

STEP 2

Read a backsight to the benchmark that is on the kerb and gutter (1.575) and book this your field notes.

This is recorded as a backsight and establishes the height of the instrument above the benchmark.

The actual Reduced Level of the Bench Mark is also recorded.

STEP 3

Sight and Book all intermediate sights that can be viewed from station S1 to S4.

Surveyor______________________ Chainmen_________________________________

Instrument No___________________ Date__________________

Backsight

Intermediate

Sight Foresight Rise Fall

Reduced

Level Top Bottom Dist Remarks

1.575 47.195 1.817 1.377 44.000 BM

Booking Sheet



Backsight

Intermediate


Reduced


1.575 47.195 1.817 1.377 44.000 BM

1.250 Station 1

0.850 Station 2

1.330 Station 3

1.580 Station 4

Booking Sheet

STEP 4

The sight to S5 will be a change point so it will be recorded as a foresight. Note when moving the

instrument the change point at S5 will become a backsight for the new set up.

STEP 5

Move instrument to position L2 and read backsight to changepoint S5



Backsight

Intermediate


Reduced


1.575 47.195 1.817 1.377 44.000 BM

1.250 Station 1

0.850 Station 2

1.330 Station 3

1.580 Station 4

1.450 1.570 1.330 24.000 S5 (CP)

Booking Sheet



Backsight

Intermediate


Reduced


1.575 47.195 1.817 1.377 44.000 BM

1.250 Station 1

0.850 Station 2

1.330 Station 3

1.580 Station 4

1.450 1.570 1.330 24.000 S5 (CP)

2.550 2.680 2.420 26.000 S5 (CP)

Booking Sheet

STEP 6

Sight and Book all intermediate sights that can be viewed from station L6 to L10. At this point

all required observations required for the task have been taken. This is called an open traverse,

we need to close the survey to check for errors.

.

STEP 7

Take sight to S11 this will be a change point so it will be recorded as a foresight. Note when moving the

instrument the change point at S11 will become a backsight for the new set up.



Backsight

Intermediate


Reduced


1.575 47.195 1.597 1.553 44.000 BM

1.250 S1

0.850 S2

1.330 S3

1.580 S4

1.450 1.570 1.330 24.000 S5 (CP)

2.550 2.680 2.420 26.000 S5 (CP)

1.980 S6

1.760 S7

1.710 S8

1.840 S9

1.920 S10

3.250 S11 (CP)

Booking Sheet



Backsight

Intermediate


Reduced


1.575 47.195 1.597 1.553 44.000 BM

1.250 S1

0.850 S2

1.330 S3

1.580 S4

1.450 1.570 1.330 24.000 S5 (CP)

2.550 2.680 2.420 26.000 S5 (CP)

1.980 S6

1.760 S7

1.710 S8

1.840 S9

1.920 S10

Booking Sheet

STEP 8

Take backsight to Sll than close traverse with foresight to B.M.

STEP 9

Total Backsights column and Tally Foresight column



Backsight

Intermediate


Reduced


1.575 47.195 1.597 1.553 44.000 BM

1.250 S1

0.850 S2

1.330 S3

1.580 S4

1.450 1.570 1.330 24.000 S5 (CP)

2.550 2.680 2.420 26.000 S5 (CP)

1.980 S6

1.760 S7

1.710 S8

1.840 S9

1.920 S10

3.250 3.400 3.100 30.000 S11 (CP)

1.831 2.021 1.641 38.000 S11 (CP)

1.258 1.418 1.098 32.000 BM



Backsight

Intermediate


Reduced


1.575 47.195 1.597 1.553 44.000 BM

1.250 S1

0.850 S2

1.330 S3

1.580 S4

1.450 1.570 1.330 24.000 S5 (CP)

2.550 2.680 2.420 26.000 S5 (CP)

1.980 S6

1.760 S7

1.710 S8

1.840 S9

1.920 S10

3.250 3.400 3.100 30.000 S11 (CP)

1.831 2.021 1.641 38.000 S11 (CP)

1.258 1.418 1.098 32.000 BM

5.956 5.958 194.000

Booking Sheet

As the survey is a closed the Backsights should equal the foresights. Due to errors and limitations of the

instruments there may be a discrepancy this is called a misclose. To determine misclose

Backsight 5.956 –

Foresight 5.958

-0.002mm Note always remember to take foresight from backsight and note negatives

In this case as there is only a -2mm misclose(Foresight is Larger than Backsight. The allowable misclose

12 x SQRT (0.194)= +/- 5.2mm therefore results are OK

STEP 10

The next step is to determine the rises and falls and book them in the appropriate column. When a sight

has lesser elevation than the previous sight, it will be classified as a “Rise”. When a sight has a greater

elevation than the previous sight, it will be classified as a “Fall”.

The Rise & Fall columns are then totaled. The misclose should be the same as the previous result (-2mm)



Backsight

Intermediate


Reduced


1.575 47.195 1.597 1.553 44.000 BM

1.250 0.325 S1

0.850 0.400 S2

1.330 -0.480 S3

1.580 -0.250 S4

1.450 0.130 1.570 1.330 24.000 S5 (CP)

2.550 2.680 2.420 26.000 S5 (CP)

1.980 0.570 S6

1.760 0.220 S7

1.710 0.050 S8

1.840 -0.130 S9

1.920 -0.080 S10

3.250 -1.330 3.400 3.100 30.000 S11 (CP)

1.831 2.021 1.641 38.000 S11 (CP)

1.258 0.573 1.418 1.098 32.000 BM

5.956 5.958 2.268 -2.270 194.000

Booking Sheet

STEP 11

The Reduced Levels are now calculated by adding the rises and subtracting the falls. Each measurement is

either added or subtracted from the previous Reduced Level starting at the known benchmark.

The Final Calculated Reduced Level should match the previous calculations

Starting Bench Mark 47.195 (Known) +

Misclose - 0.002

Ending R.L. 47.193

Therefore we would be reasonably confident that this traverse is accurate within the required parameters.



Backsight

Intermediate


Reduced


1.575 47.195 1.597 1.553 44.000 BM

1.250 0.325 47.520 S1

0.850 0.400 47.920 S2

1.330 -0.480 47.440 S3

1.580 -0.250 47.190 S4

1.450 0.130 47.320 1.570 1.330 24.000 S5 (CP)

2.550 2.680 2.420 26.000 S5 (CP)

1.980 0.570 47.890 S6

1.760 0.220 48.110 S7

1.710 0.050 48.160 S8

1.840 -0.130 48.030 S9

1.920 -0.080 47.950 S10

3.250 -1.330 46.620 3.400 3.100 30.000 S11 (CP)

1.831 2.021 1.641 38.000 S11 (CP)

1.258 0.573 47.193 1.418 1.098 32.000 BM

5.956 5.958 2.268 -2.270 -0.002 194.000

Booking Sheet

Traverse Exercise No 2



Backsight

Intermediate


Reduced


Booking Sheet

Traverse Exercise 3



Backsight

Intermediate


Reduced


Booking Sheet

Other references

Good graphical display of Rise & Fall Leveling

http://www.sli.unimelb.edu.au/planesurvey/prot/topic/top04-04-03.html

a closed traverse to measure heights at 5libvolume4.xyz/.../reductionoflevellingtutorial1.pdf ·...

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