While the debate around monocentric versus polycentric urban structures persists, a growing number of traditionally monocentric cities are pursuing a transformation agenda towards the polycentric structure. The decisions of locating and prioritising the additional centres is often based on an accessibility score, leaving out other essential factors such as the spatial variations of labour density and agglomeration externalities. This paper conducts an empirical investigation on the suitability of accessibility measures in identifying, evaluating and prioritising metropolitan activity centres (ACs), and proposes an effective density-based measure for the purpose. The proposed effective job/labour density measure integrates both a proximity dimension and a scale/size dimension, and is therefore more comprehensive than the accessibility measure. The two measures (accessibility and effective density) are applied to a case study of strategic-level ACs in the metropolitan region of Perth, Western Australia, and ACs are ranked based on their separate accessibility and effective density scores. Generally, the ACs performed poorly under both measures, with many non-AC zones having much better accessibility and effective job/labour density scores (than those designated as ACs). Nevertheless, the results show that the two measures produce markedly different ranking/prioritisation outcomes, suggesting that studies or policies that merely rely on the accessibility measure to make AC prioritisation (or exclusion) decisions could be misleading. By virtue of being more comprehensive with an integration of proximity and scale dimensions, and the ability to estimate economic agglomeration, the proposed effective density measure is, argued to be better suited and more reliable than a mere accessibility score.

尽管围绕单中心城市结构与多中心城市结构的争论仍在继续，但越来越多的传统单中心城市正在追求向多中心结构的转型议程。确定其他中心的位置和优先级的决定通常基于可访问性得分，而没有考虑其他重要因素，例如劳动密度的空间变化和集聚外部性。本文就可访问性措施在识别，评估和优先考虑大城市活动中心（AC）方面的适用性进行了实证研究，并为此目的提出了一种有效的基于密度的措施。拟议的有效工作/劳动密度衡量标准综合了接近度维度和规模/规模维度，因此比可及性衡量标准更为全面。将这两个度量（可访问性和有效密度）应用于西澳大利亚州珀斯市区的战略级AC的案例研究，并且根据单独的可访问性和有效密度分数对AC进行排名。通常，在两种措施下，AC的表现均较差，许多非AC区域的可及性和有效的工作/劳动密度得分要好得多（比那些指定为AC的区域）。但是，结果表明，这两种措施产生的排名/优先级排序结果明显不同，这表明仅依靠可访问性措施做出AC优先级（或排除）决策的研究或政策可能会产生误导。凭借更广泛的功能以及对接近度和规模维度的集成以及估算经济集聚的能力，