Job accessibility in Gauteng: measuring and visualizing location-based travel time

Abstract

Accessibility is an important indicator to measure spatial interaction and equity involving urban land-use activities and transportation systems. Transport plays a fundamental role in accessibility by influencing spatial choices and enabling communities to participate in social and economic activities with ease. Therefore, inadequate accessibility could potentially contribute to social and economic exclusion, longer commuting time, as well as spatial mismatch problems. The transport sector in South Africa suffers from the legacy of apartheid spatial planning and as a result, most of the residential and major urban areas are disconnected in terms of accessibility. Measuring job accessibility, in particular, can assist to measure spatial inequality between locations where jobs are and where people reside. The aim of this study was to model travel-time accessibility for Gauteng inhabitants from places of residence to places of work. The computation of the job accessibility measure was implemented in GIS.

GIS applications offer a variety of tools to measure and assess spatial accessibility. The analysis used the gravity measure approach to calculate accessibility and the implementation of the methodology was GIS-based. This study used Origin-Destination (OD) Cost Matrix analysis in Network Analyst tools, Proximity Analysis, and interpolation methods to achieve the study aim. The research study made use of the residential location data, population data, transportation routes data, and economic activity (as a proxy for job opportunities) data, and referred to previous accessibility studies for common accessibility standards as input data to analyse travel-time accessibility within Gauteng. The study made use of geospatial visualization techniques such as hexagon tessellations, and dasymetric maps to visually present the accessibility findings.

The major findings of the research revealed that travel-time accessibility within the study area differs based on the type of transportation mode, the availability of transport infrastructure, and places of work. The results based on travel-time to places of work using two modes of transportation modes (public and private), revealed that car users had adequate access to road network transport infrastructure and as a result had better advantage compared to those that rely on rail transportation in terms of the travel-time radius. Accessibility using the road network (private) gives a far wider access to places of work in the City of Johannesburg, City of Ekurhuleni, Emfuleni, Lesedi and Merafong City as compared to accessibility using rail network (public). The results from the location-based measure (gravity-based equation) revealed that areas with high job accessibility scores using a car are mostly located in the inner parts of the study area with a few located on the outskirts. Furthermore, the main municipalities with a higher percentage of places of work that can accessed within 30 minutes using a car are City of Johannesburg (100%), City of Ekurhuleni (100%), Emfuleni (100%), Lesedi (100%), Merafong City (100%), and Rand West City (100%), followed and the City of Tshwane (99%), Midvaal (99%), and Mogale City (99%). Moreover, accessibility to places of work using rail revealed that the City of Johannesburg (100%), City of Ekurhuleni (100%), and the Rand West City (100%) had a higher percentage of places of work located within 45 minutes.

In conclusion, the study found that more residential areas could access places of work within 30 minutes using a car with a few residential areas outside the 30 minutes catchment areas. Whereas the results from using a rail revealed a relatively high number of residential areas considered inaccessible (areas located beyond the 45 minutes threshold). Furthermore, the results revealed that there were limited places of work and accessible transport infrastructure in some municipalities such as the Emfuleni local municipality which resulted in poor job accessibility. The study recommends expanding the scope of the study area beyond a local municipality, metro and district level, to consider accessibility to places of work located outside the provincial borders of Gauteng when measuring travel-time to obtain an accurate picture of accessibility to places of work at a higher level as commuters and job seekers are not restricted to provincial boundaries. It also recommends considering data related to the influence in travel behaviour such as socioeconomic and demographic characteristics. Lastly, it encourages exploring other data that could provide a holistic overview of accessibility to places of work in Gauteng including multiple public transportation modes (i.e., buses, minibus taxis), and accessibility to a various job classes not considered in this study.