Degree of curve on plan data: arc definition against chord definition
A plan labels a curve D = 3°30′00″ with Δ = 24°15′00″ but does not say which definition of degree of curve applies. Both radii are computed and the two sets of elements compared.
Apply· about 22 minutes by hand· 5 steps
Given
An old highway plan sheet labels a horizontal curve D = 3°30′00″, Δ = 24°15′00″.
The title block does not state whether the degree of curve is by the arc definition or the chord definition.
The alignment is stationed in 100 ft stations. All distances are US survey feet.
Arc definition: D is the central angle subtended by a 100 ft arc.
Chord definition: D is the central angle subtended by a 100 ft chord.
Required
The radius implied by each definition.
The full set of curve elements under each definition.
The size of the discrepancy, and whether it matters for this curve.
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