Spiral Length Design

Abstract

In the literature, the length of a clothoid spiral usually is determined by three equations. These equations do not lead to the same length. As a result, all equations are applied and the maximum length is chosen. Of these three equations, two are based on actual and unbalanced superelevation with speed. These two equations are theoretically inaccurate. Thus, after selecting a spiral length, designers need to check the length against comfort criteria, even though these two equations are based on the same comfort criteria. Then, the length is adjusted. In fact, all parameters, such as jerk (