Compound curve: tangent distances and stationing from the main PI
Two arcs of different radius meet at a point of compound curvature. The vertex triangle gives the two tangent distances back to the main PI, and the alignment is stationed through both arcs.
Analyze· about 30 minutes by hand· 5 steps
Given
A compound curve to the right made of two arcs meeting at a PCC.
First arc: R₁ = 800.00 ft, Δ₁ = 18°30′00″.
Second arc: R₂ = 1150.00 ft, Δ₂ = 26°10′00″.
The total deflection between the back and forward tangents is Δ = Δ₁ + Δ₂ = 44°40′00″.
Station of the main PI, where the back and forward tangents intersect, = 52+30.55.
All distances are US survey feet.
Required
The elements of each arc.
The distance from the main PI back to the PC and ahead to the PT.
Stations of the PC, the PCC and the PT.
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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