The future traffic is an important target in traffic planning and road building. It is an indispensable term for determining road grade, cross-section, type of structure and road standard.

Reasonable type of road cross section could ensure the smooth vehicle flow, at the same time, it could reduce the pollution of traffic to environment through reasonable greening arrangement.

Especially calculating procedures for circle curve by cross-section and transition cur-ve of the road have been expressed and derived in detail.