Introdcution and Purpose of Fly Leveling
Introdcution and Purpose of Fly Leveling
Introdcution and Purpose of Fly Leveling
Fly levelling is a very approximate form of levelling in which sights are taken as large
as possible. In this method a line of levels is run to determine approximately reduced levels
of the points carried out with more rapidly and less precision. It is a levelling that is done to
connect benchmark to the starting point of the survey line. In this levelling only back sight
and fore sight readings are taken and auto level is moved strictly on the line joining
benchmark and starting point of survey line.[ CITATION Gau13 \l 17417 ]
If the work site is away from the benchmark, surveyor starts the work with a back
sight on the benchmark by setting instrument at a convenient point. Then he proceeds towards
the site by taking fore sights and back sights on a number of change points till he establishes
a temporary benchmark in the site. Rest of the levelling work is carried out in the site. At the
end of the work again levelling is carried out by taking a set of convenient change points till
the bench work is reached. This type of levelling in which only back sight and fore sights are
taken, is called fly levelling, the purpose being to connect a benchmark with a temporary
benchmark or vice versa. Thus the difference between fly levelling and differential levelling
is only in the purpose of levelling.[ CITATION JAS15 \l 17417 ]
Fly levelling performed when work site is very far away from the bench mark. The
surveyor starts by taking back sight at bench mark and proceed towards worksite till the finds
a suitable place for temporary BM. All works are done with respect to temporary BM. At the
end of the day the surveyors comes back to original bench mark.[CITATION Rah09 \l
17417 ]
References
Gaurav.H.Tandon, 2013. slideshare. [Online]
Available at: https://www.slideshare.net/gauravhtandon1/levelling-26905390
[Accessed 1 july 2017].