Abstract: Asymmetric clothoid curve is a constituent element of highway or railway horizontal alignment. Based on asymmetric clothoid curve equation and the principal point calculation with formula, using AutoLISP programming language nested in the AutoCAD, drawing of asymmetrical clothoid curve is achieved accurately. According to the characteristics of asymmetric clothoid curve, the drawing method is to draw clothoid curve first and then circular curve, thus too many conversions of user coordinate system can be avoided to make the drawing method more universal. The practice shows that the accuracy and efficiency of drawing can meet the requirement of application.

Key words: computer application, asymmetric clothoid curve, drawing curves, highway or railway horizontal alignment