TWO PEG TESTTWO PEG TEST

Mohd Effendi Daud (Dr. Sc)B.Surv (UTM, Malaysia) Msc (UTM, Malaysia), Dr.Sc, (Nagoya Univ., Japan)

(Geomatic Division)Faculty of Civil & Environmental Engineering,

Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor, MALAYSIA.Phone : +6074537363; +60197853740; Fax : +6074537060

E-mail : effendi@uthm.edu.my Web: http://www.fkass.uthm.edu.my/

Peg Test is a surveying operation carried out todetermine if the leveling bubble and telescope line-ofsight are parallel

The height difference m = S1-S2

L = 40m

If the instrument is the same distance from bothstaff positions, the errors are equal and cancel out

Now move the instrument outside the pegs

The height difference m’ = S1’ - S2’

If m=m’ then the instrument is OK!If NOT then the errors is e=(S1-S2)-(S1’-S2’)/L mm/m(Then error is called collimation error)

FIELDWORK 2-1o Each group will be required to perform a peg test to

check the instrument.o Record the results of the peg test in fieldbook.o Place two pegs about L = 40m apart.o Set up instrument midway between the two pegs.o Read staff on each peg, and calculate height difference.o Move instrument about L/10 = 4m beyond one of the

pegs.o Read staff on each peg again, and calculate height

difference

Collimation Error --> e = difference in the differences Acceptable error: 1mm per 20m