Abstract: The research is intent to study on how to determinate the ascription of the planar crossway section and the relative technology for define and expend its semantic mode when look the urban road as one certain spatial occupancy.The research starts at a series of the study on the road structure and relationship between roads in the crossway section and the spatial configuration of crossway.Then the article proposes use close-line to simulate road redline when visualizing selected heterogeneous road.The article also provides necessary solutions on the logistic model and data structure for that.