Horizontal Curves
 Basic Properties Of
    Horizontal Curves
 Location Of Tangent
    Points
 Setting Out
 Offsets From The Tangent
 Offsets From The Chord
 Deflection Angles
 Deflection Distances
 Quartering
 Coordinates
 Transitions Curves

Setting Out - Deflection Distances

The method of establishing a curve using deflection distances is very similar to that of deflection angles.

Deflection distances are the offset from the tangent in the first instance and the produced chord in the subsequent instances. The first offset is calculated from the chord length and radius and is shown above. The second offset, also known as the 'Standard Offset' is twice this, and remains so for the remainder of the curve. These two distances can be cut as notches on a sighting board, which then eliminates the need to measure them in the field. This is a simple method of establishing the curve, and needs a low level of technology to perform.