A method for family of $G^2$ planar cubic B\'ezier spiral
transition from straight line to circle is discussed in this
paper. This method is then extended to a pair of spirals between
two straight lines or two circles. We derive a family of cubic
transition spiral curves joining them. Due to flexibility and wide
range of shape control parameters, our method can be easily
applied for practical applications like high way designing,
blending in CAD, consumer products such as ping-pong paddles,
rounding corners, or designing a smooth path that avoids
obstacles.