Network Analysis for Walkability Based on Activity Distribution through UNA Tools (Case Study: Central Area of Tehran)

Nowadays, encouraging people to walk in the urban streets is not possible without considering attractive activities for pedestrians. Analyzing activities in the urban networks needs to determine complex parallel spatial relationships between different buildings, public spaces, and routes that connect them. In this way, urban designers and planners have started to use network- based models which analysis numerous relationships in urban space and allow the experts to use that information in urban decision making.
In this way the Urban Network Analysis Toolbox (UNA) – an open-source and free plug-in for ArcGIS – provides abilities for calculating parameters of accessibility in the road network. This solution can be used for evaluating pedestrian paths based on around activities of the network. UNA toolbox, models the built environment using three basic elements: edges, representing paths along which travelers can navigate; nodes, representing the intersections where two or more edges intersect; and buildings, representing the locations where traffic from streets enters into indoor environments or vice versa. Buildings can be replaced by any other point locations on the network.
This paper tries to calculate and visualize the centrality indicator of activities in the road segments, in the central area of Tehran. The Centrality Tools of ArcGIS toolbox can be used to compute five types of graph analysis measures on spatial networks: Reach; Gravity; closeness; betweenness and straightness. Respect to the literature reviews, activities of a street as a public space, influence on walkability. Theoretical framework of this research was focused on space syntax theory and develop the concept which emphasized structure of network integration can be influenced on activity distribution.
Therefore, in the first step, based on theoretical framework, the point of interest layer, which is generated by Tehran Municipality, was applied to select 50 layers of the retail activities and public interests, which are more attractive for pedestrians. Then the UNA toolbox was run to calculate the centrality indicator of each activity point. Then, generated value of each point was assigned spatially to the nearest road segment.  Finally, value for centrality of activities of each road segments were calculated, and the score of each road was determined. Finally, roads based on total centrality score classified and visualized with mapping in ArcGIS.The results show that there are lots of roads in central districts of Tehran that have connected paths with high centrality of attraction activities for pedestrians. For example, in this case-study, ValiAsre street,enghelab street, and Jomhoury street have the most scores in centrality indicator. Also with Changing some land uses, new connected and integrated paths could be generated which can enhance walking interests. For example, Imam-Khomeini Street has much potential to transform to attractive path for walkability with changing some activities, especially the segment between 30Tir Street and HasanAbad. From the technical implications, findings of this research shows that applying this approach provides better recognition of the high potential urban networks to enhance livability and can be used to designing and planning livable-oriented spaces, especially for regeneration the central business districts and deteriorated areas.