Organisms and other living things grow as fractals, helping to maximize space-filling ability and transmit flow efficiently. In recent years, many studies on fractals have been carried out, mostly at a geometric level, although little work has been done on fractal properties at a structural level. In fact, the capacity of geographical objects, especially road networks, is dependent not only on the geometric distribution described by a geometric fractal dimension but also on the level of structural complexity as described by a structural fractal dimension. Past studies on a structural fractal dimension are limited to a single scale and a single representation. Because different representations could lead to different results in fractal analysis, this study aims to examine the structural fractality of urban road networks by different representations. The road networks of the 100 most populous cities in the United States were examined by three commonly used topological representations. The following results were established: Despite differences in representation, structural fractality always exists; structural fractal dimensions in stroke-based representation are obviously larger than those in segment-based representation; and scale has no obvious effects on structural fractality. These results could deepen our understanding of how urban road networks evolve.

有机物和其他生物以分形的形式生长，从而有助于最大化空间填充能力并有效地传输流量。近年来，已经进行了许多关于分形的研究，尽管在结构层面对分形特性的研究很少。实际上，地理对象（尤其是道路网络）的承载能力不仅取决于以几何分形维数描述的几何分布，而且还取决于以结构分形维数描述的结构复杂程度。过去有关结构分形维数的研究仅限于单一比例和单一表示形式。由于不同的表示形式可能导致分形分析产生不同的结果，因此本研究旨在通过不同的表示形式来检验城市道路网络的结构分形性。通过三种常用的拓扑表示法检查了美国100个人口最多的城市的道路网络。建立了以下结果：尽管表示存在差异，但结构分形始终存在；基于笔划的表示形式的结构分形维数明显大于基于段的表示形式的分形维数。尺度对结构分形没有明显影响。这些结果可以加深我们对城市道路网络发展方式的理解。基于笔划的表示形式的结构分形维数明显大于基于段的表示形式的分形维数。尺度对结构分形没有明显影响。这些结果可以加深我们对城市道路网络发展方式的理解。基于笔划的表示形式的结构分形维数明显大于基于段的表示形式的分形维数。尺度对结构分形没有明显影响。这些结果可以加深我们对城市道路网络发展方式的理解。