Exploratory evaluation of road network hierarchy in small-sized cities: Evidence from 20 Greek cities

Abstract

The purpose of this paper is to explore the road network hierarchy in small-sized cities. Specifically, this study develops a mixed-evaluation method via the adoption of various criteria (readability, existence of rings roads, arteriality, multimodality, etc.), thus ending in the categorization of the studied cities (car-oriented or sustainable modes oriented). In this context, 20 cities scattered in the Greek territory are examined (30,000-100,000 inhabitants). The data, which are mainly secondary, are derived from OpenStreetMap (OSM) and Google Maps platforms as well as other sources (transport providers etc.).The results show that the road network hierarchy differs across cities significantly. For instance, neighboring cities show similar scores, either high or low, thus forming several micro-clusters dispersed in the Greek territory. Furthermore, cities with primary national significance tend to have lower scores, signifying considerable deficiencies related to sustainability issues. In general, cities proved to be rather strong in arteriality and in supporting public transport in major arterials. Additionally, ring roads (either outer or inner) that can contribute to deterring through traffic are encountered in the 50% of cities. However, the studied cities found to be inadequate in terms of facilitating active movement in major corridors, and therefore multimodality is undermined. Moreover, albeit the ring roads existence, the majority of cities still see primary arterials passing through their central areas, thus creating traffic barriers in the urban fabric. Last, the disproportionate percentage of the Main Road network does not form a simple pattern, capable of being understood by the multiple road users. The aforementioned remarks highlight that road network hierarchy in Greece, mainly have emerged rather than been defined with discrete criteria.It is shown that the present research reveals critical issues related to the re-definition of road network hierarchy towards a better level of mobility for all. Therefore, it could function as a preliminary evaluation guideline for the road hierarchy in small-sized cities, contributing significantly to supporting sustainable mobility and eventually creating more human-oriented cities.