If R is the radius of the main curve, θ the angle of deflection, S the shift and L the length of the transition curve, then, total tangent length of the curve, is

• (R - S) tan θ/2 - L/2
• (R + S) tan θ/2 - L/2
• (R + S) tan θ/2 + L/2
• (R - S) tan θ/2 + L/2
• (R - S) cos θ/2 + L/2