Engineering Surveying (LSGI2961)
Lecture 4
Control Survey
Dr Lawrence Lau
1
, Outline
Horizontal Control
1. Introduction
2. Traverse
▪ Types of Traverses
▪ Filed work
▪ Data Reduction
3. Traverse Computation
, Traverses
Data Reduction
➢ Simple calculations on measured values such as:
➢ horizontal angles from face-left and face-right angular measurements,
➢ angles between fore-sight and back-sight angular measurements,
➢ stadia readings,
➢ height differences from forward and backward height measurements, etc.
Error of Closure
➢ No measurement is perfect
➢ It is most unlikely that the raw traverse data will “close” exactly.
➢ If the error exceeds some specified or acceptable limit, the field
measurements will have to be repeated.
If the error of closure is acceptable, it is then necessary to adjust the
traverse so that it closes perfectly.
, Traverse Specifications
Uren and Price (1994)
Lecture 4
Control Survey
Dr Lawrence Lau
1
, Outline
Horizontal Control
1. Introduction
2. Traverse
▪ Types of Traverses
▪ Filed work
▪ Data Reduction
3. Traverse Computation
, Traverses
Data Reduction
➢ Simple calculations on measured values such as:
➢ horizontal angles from face-left and face-right angular measurements,
➢ angles between fore-sight and back-sight angular measurements,
➢ stadia readings,
➢ height differences from forward and backward height measurements, etc.
Error of Closure
➢ No measurement is perfect
➢ It is most unlikely that the raw traverse data will “close” exactly.
➢ If the error exceeds some specified or acceptable limit, the field
measurements will have to be repeated.
If the error of closure is acceptable, it is then necessary to adjust the
traverse so that it closes perfectly.
, Traverse Specifications
Uren and Price (1994)
