Triangulation surveying employs triangulation system which is a combination of interconnected triangles. The combination of set of triangles is called as triangulation system or triangulation figure.
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The classification of triangulation figures is performed based on the accuracy with which the length and the azimuth of a line of the triangulation are determined. The triangulation system opted can take different accuracies which is merely dependent on the extend and the purpose of the survey.
Sl.No |
Parameter |
Specification |
1 |
Average
Triangle Closure |
< 1 sec |
2 |
Maximum
Triangle Closure |
Not more
than 3 sec |
3 |
Length of
the Base Line |
5 to 15 km |
4 |
Length of
the sides of Triangle |
30 to 150
km |
5 |
Actual
Error of Base |
1 in
300,000 |
6 |
Probable
Error of Base |
1 in
1,000,000 |
7 |
Discrepancy
between two measures of the section |
10 mm sqrt (km) |
8 |
Probable
error of computed distance |
1 in 60,000
to 1 in 250,000 |
9 |
Probable
error in astronomic azimuth |
0.5 seconds |
Sl.No |
Parameter |
Specification |
1 |
Average
Triangle Closure |
3 sec |
2 |
Maximum
Triangle Closure |
8 sec |
3 |
Length of
the Base Line |
1.55 to 5 km |
4 |
Length of
the sides of Triangle |
8 to 65 km |
5 |
Actual
Error of Base |
1 in150,000 |
6 |
Probable
Error of Base |
1 in
500,000 |
7 |
Discrepancy
between two measures of the section |
20 mm sqrt(kms) |
8 |
Probable
error of computed distance |
1 in 20,000
to 1 in 50,000 |
9 |
Probable
error in astronomic azimuth |
2 seconds |
Sl.No |
Parameter |
Specification |
1 |
Average
Triangle Closure |
6sec |
2 |
Maximum
Triangle Closure |
12 sec |
3 |
Length of
the Base Line |
0.5 to 3 km |
4 |
Length of
the sides of Triangle |
1.5 to 10 km |
5 |
Actual
Error of Base |
1 in
75,000 |
6 |
Probable
Error of Base |
1 in
250,000 |
7 |
Discrepancy
between two measures of the section |
25 mm sqrt of kms |
8 |
Probable
error of computed distance |
1 in 50,000
to 1 in 20,000 |
9 |
Probable
error in astronomic azimuth |
5 |
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