Spiral Curve - Sokkia CX-62 Operator's Manual

25.4 Spiral Curve

The coordinates of the center peg and width pegs on a spiral (clothoid curve) 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 spiral to be
calculated.
• Clothoid curve is calculated by the following formula.
2
A =RL
Calculation using KA Point as reference: "KAKE Calculation 1"
AZ
Q
IP
Stationing
chainage
KA
Offset
BP
Calculation using arbitrary point between KA1 and KE1 as reference:
"KAKE Calculation 2"
AZ
Q
Q Curve length
P
Offset
KA - P Curve length
KA
KA point (P1)
IP point (P2)
Clothoid parameter A
Follow-up distance (DL)
Route width (BL)
Reference point (P1)
Point on line tangential to P1 (P2)
Clothoid parameter A
KA to P1 curve length (L)
P1 to target point (QR, QL)
Cure length (DL1, DL2)
Route width (BL)
170
25. ROUTE SURVEYING