(1) line should be made visually can naturally induce the driver's line of sight, and should maintain visual continuity.
(2) avoid plane and vertical section and a cross section limit of composite design.
(3) the horizontal and vertical alignments should correspond to each other, specification size balancing continuity and balanced with the adjacent section of the technical indicators and continuous.
(4) the limited conditions of selection of plane and vertical section of the close or when the maximum and minimum values and combinations thereof, should be considered before and after topographic technical specifications the use of influence on the actual operation speed.
(5) the cross slope and the slope be combined properly, and should be conducive to the pavement, drainage and road safety.