Space syntax analysis

As stated earlier, the use of space syntax analysis in this study is both multi-scalar and diachronic, being used to analyse both the growth and development of the city over the 65 years of its post-Partition history as well as to investigate the changing definitions, scales and relationships of Muhajir spaces in the city.

Through the subtractive process described above, a series of axial maps were developed documenting the growth and development of the city from 1949 to 2009. An axial map is a representation of a spatial network where intersecting axial lines - the longest and fewest lines of visibility and permeability in an urban grid - are drawn through all the spaces of the network. Using DepthMap

77 software, these axial models were converted into segment maps where axial lines are broken down into segments, a segment being a length of line from one intersection to the next, and a segment analysis was then run on these systems.

This analysis includes a number of space syntax measures, the most relevant to this study are Integration, Choice and step depth. Integration is the relative depth of each line segment from each other segment in the system within a prescribed radius. In simpler terms, it is the spatial accessibility of the segment, the more accessible the segment the higher the integration value and the lower the spatial depth. Choice (similar to mathematical Betweenness) is the potential of a segment to lie on the shortest and simplest path between all pairs of spaces in a system within a prescribed radius. Hence it is the ‘through movement’ potential of a space. Due to this, Choice often picks up the major through routes or thoroughfares in a spatial network, a feature that was frequently used in this research. The mathematical values attributed to each line segment for these measures are assigned, for the purposes of graphical representation, a colour within a spectrum from red to blue where high accessibility or integration appears as red whilst highly segregated lines appear as blue (for an example of this colour range see Fig. 3.04). In the context of this study, normalised Integration and Choice measures were used as this made it possible to compare results across spatial systems of varying size and scale.

Step Depth calculates the shortest route from the selected segment to all other segments in the spatial network in terms of angular deflection of the segment – or turnings away from - where a 90 degree angular change is equal to 1. The weighting used in this measure is cumulative and therefore greater the angular change or greater the number of turnings away from the point of origin, higher the step depth value.

Space syntax analysis was used to investigate the transformation of the city;

normalised Integration (NAIN) at radius ‘n’ (Rn) – the maximum scale of the city - was used to analyse the changing accessibility of various areas of the city over time as it grew and similarly normalised Choice (NACH), again at Rn, was used to analyse the change in the city’s superstructure. At the scale of the settlement, space syntax analysis has been used to investigate the accessibility

78 and segregation of various sub-clusters within the settlement. For this purpose normalized Integration at smaller radii ranging from 250m to 3000m¹⁶ depending upon the density of the spatial structure and integration of the settlement within the structure of the city, was used. In this case, the average values of street segments in each sub-cluster within the individual settlements were compared with the average value of street segments in the settlement itself.

Fig. 3.04. Segment analysis, (NAIN Rn) showing city-wide accessibility in Karachi, 1949.

Similarly, normalised Choice (NACH) was used to investigate whether communal institutions were located on street segments with high through movement potential thereby beginning to address the relationship between spatial location and the social role various communal institutions play within their community. A similar process of analysis was applied to the location and occurrence of graffiti and political propaganda to assess which political player was occupying spaces with the potential for the greatest footfall.

16 In space syntax methodology network distances upto 800m are regularly used to analyse the local scale where 800m is considered a ‘walkable’ distance in that this is approximately a 10 minute walk. Similarly, 3000-5000m is considered to be the largest radii for which the spatial network can be considered without the impact of an edge effect (Vaughan, Dhanani and Griffiths, 2013). This range of values is regularly used in space syntax analysis.

79 Whilst the cluster analysis provided a means of identifying probable Muhajir majority areas and centres, by relating the location of the urban communal elements to the space syntax model of the city, it was also possible to study the relationship of the societal role of the type of communal institution with the spatial configuration of both the city and the settlement. This process allowed for the examination of the relevance of catchment areas, territorial demarcation, proximity and density of features and inter-feature relationships for the communal institutions studied; Barelvi mosques, Shi’a imambargahs, MQM Sector and Unit offices, the local shopping street and chai-khanas. Hence this form of analysis enabled an objective spatial analysis of Muhajir space whereby underlying patterns of occupation, proximity, spatial configuration of settlements and functional distribution of land-uses were identified and explored in an attempt to describe the relationship between society and space.