How steep is that street?: Mapping ‘real’ pedestrian catchments by adding elevation to street networks

Objective: This paper develops a way of incorporating steepness into ‘ped-shed’ analyses to provide a more realistic view of urban walkability. The methodology is tested on the street network in Milton, north Glasgow, but presented such that it could be applied more widely. Method: Elevation data is added to existing and proposed street networks in Milton which enables a calculation of average walking speed per segment to be made taking into account steepness. The networks are then run through ArcGIS’s Network Analysis extension, using time (adjusted for uphill and downhill slope) as impedance. Results: ‘Real’ walkable 10-minute roundtrip catchments around neighbourhood centres are compared with 2D catchments, for existing and proposed street networks. As expected, the ‘real’ ‘ped-shed’ is smaller than the 2D ‘ped-shed’ for both networks, although the walkability of the more connected, proposed street network is less affected by steepness, most likely as a result of greater choice in route selection. Discussion: This research builds on existing established practice in walkability analysis, incorporating the often-overlooked steepness variable as a key statistical element of the walking experience. It also prompts a discussion on other factors which may affect walkability and could be included in a more sophisticated walkability index.