Using archaeological road data to evaluate limits of topography on road location: Roman roads in the Near East as a test case

Abstract The article presents a new methodological approach to understand (post-dict) the location of ancient roads based on inductive topographical analysis of existing road remains. The research is focused on analysis of spatially highly detailed dataset of Roman roads in the Near East, using selected topographical variables (maximum slope, topographic position index, vector ruggedness measure local). The identified limits of the topographic variables are used to create an isotropic slope-independent model of ‘natural corridors of movement’ using adapted ‘from everywhere to everywhere’ (FETE) method. The modelled movement corridors are then overlaid by the known Roman road network in the Near East and their overlap is calculated. The performance of the proposed isotropic model in predicting the course of the Roman roads is compared with four slope-based functions on selected Roman roads, using normalized path deviation index. The overlap between the modelled corridors and Roman roads on different scales is around 20%, suggesting that the selected topographic variables have limited explanatory power in understanding the layout of the individual roads and the Roman road network as a whole. At the same time, the isotropic model performs better in predicting course of Roman roads compared to selected cost functions, which means that the identified topographical limits are meaningful. It is argued that additional anthropic variables have stronger influence on the layout of the Roman road network and a way forward how to incorporate topographic and anthropic variables is proposed.