The use of spatial separation in the measurement of transportation accessibility

In a recent article, Allen et al. (1993) [Transpn Res. 27B, 439-449] introduce what they call a new transportation accessibility measure. The present paper raises some questions about the history of the measure and its novelty. It is argued that accessibility indices have a longer history than the authors suggest and that the proposed index of accessibility, being the average distance among a set of locations, is neither new, nor worthy of the claims made for it. In addition, some questions are raised about the associated empirical results.