Doctoral Degrees (Logistics)

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Browsing Doctoral Degrees (Logistics) by browse.metadata.advisor "Krygsman, Stephan"

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    Designing travel behaviour change interventions: a spatiotemporal perspective
    (Stellenbosch : Stellenbosch University, 2017-12) Van Dijk, Justin Tycho; Krygsman, Stephan; Nel, Hannelie; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Logistics. Logistics.
    ENGLISH SUMMARY : Against the background of unprecedented growth in private vehicle ownership and the entrenchment of the private car in everyday life, the past decades have seen a growing and ongoing academic and policy debate on how to encourage individuals to change to more sustainable ways of travelling; for instance, with voluntary travel behaviour change (VTBC) interventions. VTBC interventions aim to alter travel behaviour by providing information. In recent years, a large body of research has focused on the evaluation of the effectiveness of these programmes. However, no consensus has been reached on the question of whether a broad implementation of VTBC programmes is effective in stimulating people to use more sustainable ways of travelling. This dissertation argues that location-aware technologies, particularly GPSenabled smartphones, could potentially augment the research on VTBC interventions. Smartphones can not only source data (such as place and time of travel or activity) but can also provide individuals with real-time information, feedback, and suggestions for alternative behaviour or travel options.. However, between sourcing the data and relaying feedback to individual commuters, significant research is required on how to obtain, clean, and interpret the data, as well as on how to account for individual spatiotemporal accessibility. GPS data need to be collected and analysed systematically; especially in the context of evaluating the effectiveness of VTBC interventions in which effect sizes are known to be small and inconspicuous. As such, the translation of raw GPS trajectories into activity episodes and the best estimation of a travelled route are pivotal. Methods of activity recognition were explored with advanced machine learning algorithms, and two approaches for identifying travelled routes were proposed. Furthermore, it was demonstrated how spatiotemporal measurements could aid the design of VTBC interventions. Attention was drawn to the time-geographical concepts of activity spaces and potential path areas. Based on the examination of GPS tracks with different two-dimensional operationalisations of activity spaces, it was found that the density of opportunities within an activity space is related to the size of the activity space: larger activity spaces have lower densities of opportunities than smaller activity spaces. This may suggest that individuals who have a low opportunity density are less likely to respond to external stimuli and/or awareness programmes than individuals who have a high opportunity density. In turn, potential path areas were used to establish to what extent individuals have different spatiotemporal opportunities that will enable behavioural change in travel and activity. The findings indicate that location-aware technologies hold great potential to supplement transport geographical-research. Moreover, the results show that the incorporation of spatiotemporal measurements is crucial to consider for the design, implementation, and evaluation of VTBC interventions. The added value of seemingly new technologies, such as GPS, is that they can be easily integrated into a larger spatiotemporal framework of analysis. However, one has to be careful not to consider GPS as a panacea, because GPS data and technology also have some drawbacks. Careful consideration should go into application development, sample selection, site selection, and data imputation.
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    The impact of transport accessibility and spatial equity on employment outcomes
    (Stellenbosch : Stellenbosch University, 2024-03) Van der Merwe, Jacomina Magdalena; Krygsman, Stephan; Woolard, Ingrid, 1970-; Papps, Kerry; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Logistics.
    ENGLISH SUMMARY: Addressing unemployment and income inequalities in transport and land-use policies is important, particularly in South Africa, which is currently experiencing one of the highest unemployment rates and income inequality in the world. South Africa has also seen a rise in the number of discouraged job seekers, which accounted for 14% of the labour force in 2021. These are individuals who want to work but have become too discouraged to actively search for employment. The primary aim of this research is to understand how transport, measured by accessibility and general transport cost components, such as commuting cost and travel time, affects the labour market in South Africa. It highlights the horizontal and vertical spatial equity impacts and the differentiated impact on different income groups. Previous research has proven the impact of a spatial mismatch on the probability of an individual becoming employed and the link between transport accessibility and employment status, but it ignores its impact on an employee’s decision to remain in employment, as well as the decision to stop searching for a job. This research first highlights the unequal distribution of accessibility across space and different income groups in the City of Cape Town. Using unique tax administrative data together with TomTom road network and speeds data, the research shows that the impact of congestion has a greater effect on access to job opportunities for residents of low-income locations compared to those from high-income locations. This reinforces spatial inequality. The research further focuses on the notion of job seekers becoming discourage and the impact of transport cost on their decision not to search for employment. Third, the research provides evidence that longer commuting distances between an employee’s residence and work location reduce employment duration for lower-income employees. The converse it true for higher income individuals. This shows a positive relationship between commuting distance and employment duration. The differentiated impact that transport has on the labour market for different income groups can be incorporated in transport and land-use policy and planning that aim to improve employment and equity outcomes. Last, the impact of land-use policy on accessibility is investigated in a case study, should affordable housing be provided closer to the two main employment hubs in the City of Cape Town. This could address vertical spatial equity, as measured by accessibility to employment in the city.
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    Road infrastructure improvement for efficient utilisation of the agricultural potential : a case study of Morogoro, Tanzania
    (Stellenbosch : Stellenbosch University, 2018-03) Fungo, Emmanuel; Krygsman, Stephan; Nel, Johanna H.; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Logistics. Logistics.
    ENGLISH SUMMARY : The Morogoro region in Tanzania is endowed with diverse sources of water, fertile land and a good climate, suitable for crop cultivation. Only 29 percent of the arable area, however, is used for agricultural purposes. Inadequate and poor rural transport is partly to blame for the underutilisation of the agricultural potential. Rural transport provides assurance for the supply of the agricultural inputs and facilitates for the delivery of the farm outputs to the markets. Improved rural road infrastructure and transport services stimulate the increase in agricultural production through lowering of the transport price of farm inputs and outputs. Little is known, however, about the extent of agricultural production improvement following the road improvement. The conventional road economic evaluation tools such as Highway Development and Management (HDM-4) and Roads Economic Decision (RED) do not address this issue. These tools concentrate on the direct road user cost savings. Due to the low volume of traffic on rural roads, these savings are not substantial. However, rural road improvement and improved accessibility may result in a substantial impact on price and production of agricultural products. This research illustrates the impact of the road condition and trip distance on the transport price and transport cost of agricultural products. The research also establishes the relationship between transport price and agricultural production. Using the data collected from transport operators and road agencies, statistical relationships between transport price, trip distance and transport cost were established. The results show that transport price per ton-km decreases as the trip distance increases, reflecting factors such as economies of distance. However, the very high transport price over short distances can be attributed to the poor condition of rural roads and low vehicle utilisation. Transport price decreases with transport cost, indicating a competitive transport market. Longer distance trips are expected following rural road improvement, resulting in higher vehicle utilisation. Competition within the transport market is also expected to increase. Furthermore, the Tanzania National Panel Survey (NPS) data of 2012/13 was used to establish the relationship between transport price, access to the market and crop yield. Reduction of the transport price shows a positive impact on crop yield with an elasticity of -0.291. It was also found that farmers who have access to the bigger markets are associated with higher crop yield. When comparing agricultural benefits and road user cost savings for the low volume rural road, the results show that agricultural benefits were roughly three times higher than the road user cost savings. Finally, the research developed a low volume rural road economic appraisal framework which takes into account agricultural benefits, the effect of the trip distance as well as the effect of transport price.