Three types of fractal dimensions were presented to characterize the spatial structure of transport networks. The geographical meanings of these dimensions were illuminated and the methods of the determination of them were illustrated. The three fractal dimensions can be expressed as follows. 1 Length radius dimension: it is always defined by the expressionL(r)∝r D L where r is radial distance, L(r) is total length of communication lines in the area of π r 2 , and D L is the frac...