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TIME-SERIES ANALYSIS OF ACCESSIBILITY IN THE CITY OF JOHANNESBURG. N Lionjanga and C Venter SATC 2017. Contents. Introduction Research objectives Literature review Methodology Results Conclusions and recommendations. 1. Introduction.
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TIME-SERIES ANALYSIS OF ACCESSIBILITY IN THE CITY OF JOHANNESBURG N Lionjanga and C Venter SATC 2017
Contents • Introduction • Research objectives • Literature review • Methodology • Results • Conclusions and recommendations
1. Introduction • The study is based on three townships in the City of Johannesburg: • Public Transport challenges: • Poor accessibility • Poor mobility • High public transport costs • Improving accessibility is a policy objective: • White Paper on National Transport Policy • National Development Plan • Measuring accessibility over time provides a potential tool to assess policy performance.
2. Research objectives • Through a case study of origins in Alexandra, Soweto and Orange Farm for the years 2009, 2011 and 2013, the objectives of the research are: • To measure the time-series developments of accessibility to jobs from selected origins in the CoJ. • To measure the effects of BRT implementation on the accessibility to jobs from Soweto.
3. Literature review: Accessibility • Accessibility describes the ease or difficulty of reaching a desired destination or opportunity from a particular location. • Accessibility describes the ease or difficulty of reaching a destination or opportunity from a particular location. • Accessibility describes the ease or difficulty of reaching a destination or opportunityfrom a particular location.
3. Literature review: Access Envelope Technique • Developed by UP and HSRC in 2014. • Implemented using a Geographic Information System (GIS). • Access measure: Net Wage After Commute (NWAC).
4. Methodology Input data: • Spatial distribution of jobs • Average potential wage levels • Public transport routes • Walking times • Waiting times • Public transport fares • Speed of public transport modes Figure 1: Spatial distribution of jobs in the CoJ. Source: Gauteng Transport Model job location data.
4. Methodology • Public transport modes and associated fares. Figure 2: 2009 Public transport fares
4. Methodology • Public transport modes and associated fares. Rea Vaya 2011 fares: Feeder: R4.50 Trunk: R8.50 Feeder+Trunk: R12.00 Figure 3: 2011 Public transport fares
4. Methodology • BRT flat fare structure. Figure 3: 2011 Public transport fares
4. Methodology • Public transport modes and associated fares. Figure 4: 2013 Public transport fares
4. Methodology • The access envelope methodology selects the closest mode or combination of modes to maximise the NWAC for each commuter trip. • Maximising the NWAC: • Trade-off of travel time and travel costs. • Typically the lowest cost mode (including walking). • Beyond travel time budget: higher cost but faster modes may be used to minimise travel time penalties.
4. Methodology • Typical NWAC surface. Figure 5: NWAC surface Soweto 2009
4. Methodology • Summary measures allow for comparison over time and across origins. 1. Number of jobs accessible with NWAC > R85/day 2. Number of jobs accessible within 60 minutes of travel time 3. Average NWAC of the closest 200,000 jobs
5. Results • Alexandra NWAC surface. 2009: NWAC > R85: 2,856,172 TT< 60min: 2,147,933 Avg NWAC: R114.00 2013: NWAC > R85: 3,057,583 TT< 60min: 2,054,566 Avg NWAC: R137.00 Figure 6: Alexandra 2009 Figure 7: Alexandra 2013
5. Results • Orange Farm NWAC surface. Orange Farm 2009: NWAC > R85: 566,693 TT< 60min: 90,954 Avg NWAC: R82.00 Alexandra 2009: NWAC > R85: 2,856,172 TT< 60min: 2,147,933 Avg NWAC: R114.00 Figure 6: Alexandra 2009 Figure 8: Orange Farm 2009
5. Results • Orange Farm NWAC surface. 2009: NWAC > R85: 566,693 TT< 60min: 90,954 Avg NWAC: R82.00 2013: NWAC > R85: 1,520,253 TT< 60min: 77,942 Avg NWAC: R95.00 Figure 8: Orange Farm 2009 Figure 9: Orange Farm 2013
5. Results • Soweto: The effect of Rea Vaya Phase 1A. 2011: NWAC > R85: 2,389,384 TT< 60min: 742,800 Avg NWAC: R124.00 2013: NWAC > R85: 2,669,232 TT< 60min: 946,634 Avg NWAC: R133.00 27% Figure 10: TT surface Soweto 2011 Figure 11: TT surface Soweto 2013
5. Results • Distribution of accessibility within townships. Figure 12: Accessibility distribution
6. Conclusions • Affordability of public transport services plays a critical role in changing accessibility patterns over time. • The marginal benefits of improving accessibility from regions with high accessibility are low. • The BRT contributed to improving accessibility levels. • The change in the BRT fare structure from 2011 to 2013 contributed to improving accessibility levels offered by the BRT. • The township with high accessibility had a more uniform or equitable distribution of accessibility throughout the township.
6. Recommendations for further research • Increase the reasonable NWAC of R85/day from one analysis year to the next. • Study the effects of job location and availability on accessibility by adjusting the number of jobs on the surface. • Incorporate forced transfer points along public transport routes: minibus taxi routes. • Calibrate the access envelope technique to verify its use as a land use and transport planning tool.
Acknowledgements • The SATC for their financial support. • Willem Badenhorst and Johan du Toit from Mapable in assisting with software development.