Family of G/sup 2/ cubic transition curves

Walton & Meek (1996) obtained a fair G/sup 2/ cubic transition spiral curve joining a straight line and a circle. We derive a family of cubic transition spiral curves joining them. We not only simplify and extend their analysis but also provide more degrees of freedom with less restrictive shape control parameters. The idea of straight line to circle transition has been extended to straight line to straight line transition which is more flexible and comfortable for practical use.