Unit 7.1. Horizontal Curves Flashcards
The point at which the alignment changes from straight to circular is known as the ___.
BC (beginning of curve)
The ___ is located distance T (subtangent) from the PI (point of tangent intersection).
BC (beginning of curve)
The BC is located distance ___ from the ___.
T (subtangent)
PI (point of tangent intersection)
The ___ is dependent on the central angle and the value of R (radius).
length of circular curve (L)
The length of circular curve (L) is dependent on the ___ and the value of ___.
central angle
R (radius)
The point at which the alignment changes from circular back to tangent is known as the ___.
EC (end of curve)
Since the curve is symmetrical about the PI, the EC is also located distance T from the PI.
From geometry we recall that the radius of a circle is perpendicular to the tangent at the point of tangency.
Therefore, the radius is perpendicular to the back tangent at the BC and to the forward tangent at the EC. The terms “BC” and “EC” are also referred to by some agencies as PC (point of curve) and PT (point of tangency), and by others as TC (tangent to curve) and CT (curve to tangent).
A ___ consists of two (or more) circular curves between two main tangents joined at point of compound curve (PCC).
compound curve
A compound curve consists of two (or more) circular curves between two main tangents joined at ___.
point of compound curve (PCC)
Curve at PC is designated as ___ and curve at PT is designated as ___.
1 (R1, L1, T1, etc)
2 (R2, L2, T2, etc)
Curve at ___ is designated as 1 (R1, L1, T1, etc) and curve at ___ is designated as 2 (R2, L2, T2, etc).
PC
PT
___, though pleasing to the eye, would bring discomfort to motorists running at design speed. The instant change in direction at the PRC brought some safety problems
Reversed curve
are being used with great success on park roads, formal paths, waterway channels, and the like.
reversed curves
