Stake a circular curve by tangent offsets and by chord offsets
A 700 ft radius curve is laid out with a tape alone: first by rectangular offsets from the back tangent, then by successive offsets from the prolonged chord, with the approximate and exact formulas compared.
Apply· about 24 minutes by hand· 5 steps
Given
A simple circular curve with R = 700.00 ft and Δ = 22°00′00″, curving to the right.
Station of the PC = 18+40.00.
The site is flat and open. No total station is available; the curve is to be set with a tape and a right-angle prism.
Stakes are wanted at every full station and at the PT.
All distances are US survey feet.
Required
The arc length and the station of the PT.
A table of tangent distances and tangent offsets for each staked point, measured from the PC along the back tangent.
The equivalent chord-offset values for the alternative method.
A comparison of the exact tangent offset with the common approximation.
Work it through yourself before reading on - the solution below shows every step, so there is no way to skim it without giving the answer away.
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