1.6  On-site Inspection of Surveying Instruments

On-site inspection to check that all the surveying instruments work normally has been conducted at each observation station prior to the commencement of the survey in 1999.

 

1.6.1  On-site inspection of TS

(1)     On-site inspection of the range measurement

          On-site inspection of the range measurement has been conducted by applying 3-point method using the external geodetic survey monuments (short pillars).

(Refer to Figure 4.)

 

 

 

 

 

 


 

Figure 4  Drawing to explain the concept applied for on-site inspection of the range measurement (3-point method)

 

Compared to NET2B, the discrepancy was found to be quite significantly large with TC2002. The reason for this large discrepancy was that the reflection sheet used exclusively for NET2B could not be applied for observation using TC2002 and therefore, the inspection had to be conducted, using the reflection mirror (APS34) manufactured by Sokkia. According to explanation from Sokkia, the precision of their reflection mirror (APS34) may be affected slightly when it is used to measure a range that is closer than 30m.

 


Table 10  Results of the on-site inspection of the range measurement

station

Name of equip-ment

S/N

(a)

s (m)

(b)

a-b (m)

(c)

c+d (m)

(a) – (c)

Mean (m)

(a) – (c)

Maximum discrepancy

(mm)

Inspection date

Koganei

NET2B

31481

29.5935

29.5950

29.5934

29.5940

1.6

10/13

NET2B

31788

29.5947

29.5946

29.5945

29.5946

0.2

10/13

TC2002

359698

29.5959

29.5955

29.5974

29.5963

1.9

11/17

Kashima

NET2B

31481

24.5286

24.5282

24.5284

24.5284

0.4

10/23

NET2B

31788

24.5285

24.5275

24.5285

24.5282

1.0

10/22

TC2002

359698

24.5289

24.5289

24.5311

24.5296

2.1

10/22

Miura

NET2B

31481

47.9554

47.9557

47.9559

47.9557

0.3

11/12

NET2B

31788

47.9557

47.9551

47.9566

47.9558

1.5

11/12

TC2002

359698

47.9569

47.9552

47.9577

47.9566

2.5

11/12

Tateyama

NET2B

31481

8.3884

8.3880

8.3878

8.3881

0.6

11/09

NET2B

31788

8.3886

8.3882

8.3891

8.3886

0.9

11/09

TC2002

359698

8.3888

8.3879

8.3902

8.3890

2.3

11/09

 

(2)     On-site inspection of the angle measurement

          On-site inspection of the angle measurement has been conducted by (1) setting TS at the short pillars; (2) collimating other short pillars or long pillars with this TS; (3) measuring the angle of the same target with several other TSfs (refer to Figure 5) and (4) comparing the measured values to confirm the performance of the angle measurement.

 

 

 

 

 

 

 

 

 


Figure 5      Drawing to explain the concept applied for on-site inspection of the angle measurement

 

Table 11  Results of the on-site inspection of the goniometric system

Observation station

Name of equipment

S/N

Horizontal angle

(deg. e g)

Vertical angle1

(deg. e g)

Vertical angle 2

(deg. e g)

Inspection date

Koganei

NET2B

31481

268.1804

-0.0454

2.1650

10/13

NET2B

31788

268.1808

-0.0457

2.1650

10/13

TC2002

359698

-

-

-

11/16

Kashima

NET2B

31481

303.3518

-0.0459

-0.0630

10/23

NET2B

31788

303.3521

-0.0501

-0.0635

10/22

TC2002

359698

303.3520

-0.0503

-0.0638

10/22

Miura

NET2B

31481

59.5740

-0.0324

-0.0857

11/12

NET2B

31788

59.5743

-0.0324

-0.0856

11/12

TC2002

359698

59.5742

-0.0329

-0.0906

11/12

Tateyama

NET2B

31481

258.1232

-0.1646

-0.1949

11/09

NET2B

31788

258.1223

-0.1647

-0.1952

11/09

TC2002

359698

258.1243

-0.1705

-0.2010

11/09

 

1)      At Tateyama station, the discrepancy of the measurement of horizontal angle was found to be quite significantly large. The reason for this large discrepancy was because the target was only 8m away. The actual discrepancy is equivalent to only 0.7mm in distance and can therefore be considered to be within the tolerable range of measurement error.

 

2)      At Koganei station, on-site inspection using TC2002 was not possible because the permission to enter the rooftop of Seiyu Storesf s where azimuth marker was established, was restricted to a very limited amount of time. Therefore, this inspection was conducted at Miura station one day before the survey was scheduled to start at Koganei station (November 16th).

 

3)      As a result of the on-site inspection of TC2002 for use in Koganei station that was conducted at Miura station, the discrepancy of horizontal angle was found to be 1 second.

 

 


1.6.2  On-site inspection of GPS

On-site inspection of GPS was conducted by setting a temporary base line randomly at a location where the sky was open above and comparing the range of the base line measured by GPS and TS. To secure the accuracy of the inspection, the measurements were compared after switching over the position of the antenna of GPS and the position of the reflection sheet and TS to prevent their positions from deviating (refer to Figure 6).

 

 

 

 

 

 

 

 

 

 

 

 


Figure 6  Drawing to explain the concept applied for the on-site inspection of GPS


Table 12  Results of the on-site inspection of GPS

Observation station

Name of equipment

S/N

Base line 1

(m)

Base line 2

(m)

Base line 3

(m)

Base line 4

(m)

Base line 5

(m)

Inspec-tion date

Koganei

GPS

1741, 1746, 6732

62.2393

46.4643

60.2012

-

-

10/13

NET2B

31788

62.2410

46.4631

60.2012

-

-

Discrepancy (mm)

-1.7

1.2

0.0

-

-

Kashima

GPS

1693, 1741, 1746, 6732

34.4697

43.0530

24.3169

20.6703

24.2735

10/19

NET2B

31788

34.4687

43.0529

24.3194

20.6706

24.2726

Discrepancy (mm)

1.0

0.1

-2.5

-0.3

0.9

Miura

GPS

1693, 1746, 6732

44.0392

32.3560

43.3745

-

-

11/05

NET2B

31788

44.0368

32.3559

43.3759

-

-

Discrepancy (mm)

2.4

0.1

-1.4

-

-

Tateyama

GPS

1693, 1746, 6732

15.8045

18.8596

-

-

-

11/08

NET2B

31788

15.8055

18.8630

-

-

-

Discrepancy (mm)

-1.0

-3.4

-

-

-

 

The discrepancy of all the base lines that have been inspected was less than 3.4mm when compared with TS measurements. Therefore, the surveying instruments of GPS were all confirmed to be meeting the specifications of required standard performance.

 

 


1.6.3  On-site inspection of the level

On-site inspection of the level has been conducted by checking the flat-levelness of the collimation line of the level and the compensator (automatic correction unit) respectively through the application of pile driving check method (refer to Figure 7).

1)      Pile driving check method applied here was a method of checking and adjusting the flat-levelness of the collimation line of the level by applying the principle that the deviation of the collimation line increases proportionately as the distance between the level and staff gets farther away.

 

 

 

 

 

 

 

 

 


Figure 7  Drawing to explain the concept of pile driving check method

 

2)      Compensator functional check method applied here was a method to compare the observation value gained from a level that has been adjusted to be placed at a position where the bubble is at the center and the observation values gained from a level that has been adjusted to be placed at a position where the bubble is deviated extremely to crosswise/lengthwise directions. 

 

 

 

 

 

 

 

 


Figure 8  Drawing to explain the concept of compensator functional check method

 

Table 13  Results of the on-site inspection of the level

Observation station

Name of equipment : S/N

Pile driving check (mm)

Compensator functional check (mm)

Inspection date

Koganei

DiNi11        :  100312

0.13

Crosswise

0.01

10/18

Invar staff    :  12562,12564

Lengthwise

0.01

Kashima

DiNi11        :  100312

0.01

Crosswise

0.13

10/23

Invar staff    :  12562,12564

Lengthwise

0.02

Miura

DiNi11        :  100312

0.11

Crosswise

0.15

11/18

Invar staff    :  12562,12564

Lengthwise

0.09

Tateyama

DiNi11        :  100312

0.04

Crosswise

0.06

11/09

Invar staff    :  12562,12564

Lengthwise

0.01

 

(a)  The result of the pile driving check showed evidently that the levels used for this survey all meet the standard specifications required for first class leveling.

 

(b)  The result of the compensator functional check showed evidently that the compensators used for this survey all function normally.