Parabola - Sokkia im-101 Operator's Manual

25.5 Parabola

The coordinates of the center peg and width pegs on a parabola can be found from the coordinates of the
reference point and curve properties.
It is then possible to proceed with the setting-out of the center peg and width pegs
• Select a calculation menu depending on the section of the parabola to be calculated.
• Parabola is calculated by the following formula.
x 3
y = ----------- -
6RX

Abbreviations used in parabola calculation
BTC: Beginning of transition curve
BCC: Beginning of circular curve
ETC: End of transition curve
ECC: End of circular curve
Calculation using BTC Point as reference:
"BTCBCC Calculation 1"
AZ
Q
IP
Stationing
chainage
BTC
Offset
BP
Calculation using BCC as reference: "ECCETC Calculation"
AZ
ETC
ECC-ETC
Curve length
Q
Q Stationing Chainage
Stationing Chainage
ECC
BP
127
25. ROUTE SURVEYING