The invention relates to a ''two points''
line element method for road
route plane alignment design, and belongs to the technical field of road
route plane alignment design curve methods. The ''two points''
line element method is characterized by comprising six basic
line element types of a straight tangent, a circular curve, a forward / backward
complete type convolute curve, and a forward / backward incomplete type convolute curve, and comprising eight basic parameters of a coordinate, a tangential clearance angle and a
radius which are relevant with a starting point of the line element, a coordinate, a tangential clearance angle and a
radius which are relevant with an end point of the line element, a line element
deflection angle and a line element length. Four typical independent parameters are a coordinate of the starting point, a tangential clearance angle of the starting point, a
radius of the starting point and a coordinate of the end point. During the process of line element designing, three parameters relevant with the starting point are known, so that a person only needs to set the coordinate of the end point, then the only six basic line element type element curve can be determined, just like that a straight line is only determined by two points. The ''two points'' line element method disclosed by the invention has the effects and benefits that the only six basic line element type element curve can be determined through the two points; the line element end point position, the line element shape and the
route alignment are easy to control, the control of coordinate positions to the line element is emphasized, and conforming to the custom of route design and
coordinate control of construction paying-off is realized.