Using Archaeological Road Data to Evaluate Limits of Topography on Road Location: Roman Roads in the Near East as a Test Case

The article presents a new methodological approach to understanding (post-dicting) the location of ancient roads based on an inductive topographic analysis of existing road remains. The research is focused on the analysis of a spatially highly precise dataset of Roman roads in the Near East, using selected topographic variables (maximum slope, topographic position index, vector ruggedness measure). The identified limits of the topographic variables are used to create an isotropic (direction-independent) model of ‘natural corridors of movement’ using an 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 overlap between the modelled corridors and Roman roads is around ~ 25%, suggesting that the selected topographic variables and slope categories have limited explanatory power in understanding the layout of the Roman road network as a whole. The performance of the isotropic model is compared to four selected slope-based anisotropic functions (Tobler, Naismith, Herzog, Llobera-Sluckin). It is shown that the isotropic model incorporating a limited number of topographic variables better explains the location of Roman roads than the selected functions. It is argued that these results suggest that additional anthropic, cultural variables have a stronger influence on the layout of the Roman road network, and an alternative approach on how to incorporate topographic and anthropic variables is proposed.