Topcon ES-101 - 25.4 Spiral Curve

25. ROUTE SURVEYING
172
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.
A
2
=RL
Calculation using KA Point as reference: "KA®KE Calculation 1"
Calculation using arbitrary point between KA1 and KE1 as reference:
"KAKE Calculation 2"
25.4 Spiral Curve
KA
IP
Q
BP
Offset
Stationing
chainage
AZ
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)
Q
Offset
KA
P
AZ
KA - P Curve length
Q Curve length