Accessibility in a Post-Apartheid City: Comparison of Two Approaches for Accessibility Computations

Many authors argue that issues related to interpretability, lack of data availability, and limited applicability in terms of policy analysis have hindered a more widespread use of accessibility indicators. Aiming to address these aspects, this paper presents two accessibility computation approaches applied to Nelson Mandela Bay in South Africa. The first approach, a household-based accessibility indicator, is designed to account for the high diversity both among the South African society and in terms of settlement patterns. Besides OpenStreetMap (OSM) as its main data source, this indicator uses a census and a travel survey to create a synthetic population of the study area. Accessibilities are computed based on people's daily activity chains. The second approach, an econometric accessibility indicator, relies exclusively on OSM and computes the accessibility of a given location as the weighted sum over the utilities of all opportunities reachable from that location including the costs of overcoming the distance. Neither a synthetic population nor travel information is used. It is found that the econometric indicator, although associated with much lower input data requirements, yields the same quality of insights regarding the identification of areas with low levels of accessibility. It also possesses advantages in terms of interpretability and policy sensitivity. In particular, its exclusive reliance on standardized and freely available input data and its easy portability are a novelty that can support the more widespread application of accessibility measures

A people-centred view on paratransit in South Africa

Paratransit provides a valuable service offering as a flexible and substitutional mode between formal transit and private car. When it evolves to compete with more formal transit modes, efforts are made to formalise it. As in many developing countries, the South African government generally views paratransit as a necessary nuisance, emerging and evolving in the absence of more formal transit services. Our paper aims to contribute by providing a more comprehensive context for the South African case: how specific Apartheid laws contributed to the formation of the mode and how deregulation provided a fertile ground for its exponential growth. The industry has evolved into an informal yet well-organised system that dominates the local transit market. Contrary to the popular view that the industry is an amorphous whole, this paper aims to create a more people-centred view of an industry that is made up of individuals trying to carve an existence in a harsh economic environment. We show how, if approached correctly, paratransit is more likely part of the land use and transport solution, and not a problem as it is often perceived to be.The second author was funded through the Mobility Cultures in Megacities fellowship program, a joint initiative between the Technical University of Munich and the Institute for Mobility Research (ifmo), a research facility of the BMW Group.http://www.elsevier.com/locate/citieshj2014ai201

Testing self-perception theory with agent-based simulation

Paper presented at the 12th International Workshop on Agent-based Mobility, Traffic and Transportation Models, Methodologies and Applications (ABMTrans 2023) March 15-17, 2023, Leuven, Belgium.Conventional wisdom is that a person's attitude towards an issue dictates their behaviour. In contrast, self-perception theory accounts for how a person forms their attitude. In the context of this paper, the theory asserts that a person can, in the absence of prior experience, establish an attitude towards cycling based on observing their own, hopefully, positive experience. The adaptive agent-based model, MATSim, allows one to test the self-perception theory. The case study in Cape Town, South Africa, demonstrates that as much as 7.8% of people introduced to cycling will experience it as positive, opening the door for adoption.https://www.journals.elsevier.com/procedia-computer-sciencehj2023Industrial and Systems Engineerin

Applying min-max k postmen problems to the routing of security guards

The most essential and alluring characteristic of a security estate is the estate's ability to provide 24-h security to its residents, of which the continual patrolling of roads and paths is vital. The objective of this paper is to address the lack of sufficient patrol route design procedures by presenting a tabu search algorithm capable of generating multiple patrol routes for an estate's security guards. The paper shows that the problem of designing these routes can be modelled as an Arc Routing Problem, specifically as min-max k postmen problems. The algorithm is illustrated with a real problem instance from an estate in Gauteng, South Africa. The patrol routes generated by the algorithm provide a significant improvement in the even patrolling of the road network, and a more balanced work distribution among guards. The algorithm is also tested on several benchmark problems from literature.http://www.palgrave-journals.com/jors/index.htm

Generating intra and inter-provincial commercial vehicle activity chains

Modelling large-scale traffic flow systems at a disaggregate level can be data intensive as it requires extensive knowledge about the activities and activity chains of vehicles. This paper focuses on activity chain generation for commercial vehicles. We use a large sample of GPS records to extract a complex network and sample chain characteristics from. The paper makes a valuable contribution in both its methodology, and in its focus on intra and inter-provincial vehicle populations simultaneously. The simulated chains are validated in terms of vehicle kilometrekilometres travelled and its spatiotemporal accuracy, comparing favorably in both.South African National Roads Agency Limited (SANRAL) and South African National Research Foundation (NRF).http://www.journals.elsevier.com/procedia-social-and-behavioral-scienceshb201

An agent-based implementation of freight receiver and carrier collaboration with cost sharing

Freight transport stakeholders can benefit from collaborative planning. Unfortunately, appropriate decision and planning support tools are lacking. Consequently, freight stakeholders remain unaware of collaboration opportunities and the potential benefit of those coalitions. This paper focuses on implementing collaboration between urban freight receivers and carriers. Collaboration takes the form of cost-sharing among coalition members when receivers are willing to extend their time windows. Rigorous experiments confirm the behavioural sensitivity of the model. A realistically-sized case study in the City of Cape Town, South Africa, demonstrates the usability of the agent-based simulation model. The case study considers the impact of collaboration on after-hour deliveries. Results indicate that delivery cost reduces significantly (nearly 30%) when carriers and receivers are willing to collaborate and adopt after-hour deliveries - the carrier’s fleet composition changes to favour fewer but larger vehicles.https://www.sciencedirect.com/journal/transportation-research-interdisciplinary-perspectivespm2022Industrial and Systems Engineerin

Real driving emissions data : Isuzu FTR850 AMT

RDE is becoming a necessary element of the emissions certification of automotive vehicles. Real Driving Emissions (RDE) helps to ensure that the regular operation of a car, or heavy vehicle, is still within the acceptable emissions standards while driving under normal conditions. RDE is monitored by connecting a Portable Emissions Measurement System (PEMS) to the exhaust of the tested vehicle, which measures the pollutant concentrations as the car or truck drives along a standardised route. The data described in this paper is the raw, detailed PEMS records of a heavy goods vehicle, recorded at a rate of 1Hz, over multiple trips on an urban route in South Africa. The data includes the pollutant concentrations of CO, CO2, NO and NO2, ambient conditions, and vehicle diagnostics collected from different sensors mounted to the vehicle during the field tests. We performed no additional analysis on the data. The value of the data is in allowing researchers to (a) develop and test machine learning algorithms that predict the instantaneous pollutant concentrations or (b) studying the variance of pollutant concentrations that occurs under typical driving conditionshttps://www.journals.elsevier.com/data-in-brief/dm2022Industrial and Systems Engineerin

Heterogeneous Tolls and Values of Time in Multi-agent Transport Simulation

In evolutionary algorithms, agents' genotypes are often generated by more or less random mutation, followed by selection based on the fitness of their phenotypes. This paper shows that elements of this principle can be applied in multi-agent transport simulations, in the sense that a router, when faced with complex interactions between heterogeneous toll levels and heterogeneous values of time, can resort to some amount of randomness rather than being able to compute the exact best solution in every situation. The computational illustrations are based on a real world case study in the province of Gauteng, South Africa

Towards a simulation of minibuses in South Africa

After private cars, minibus taxis are the most common transport mode in South Africa. Especially for low-income citizens living in townships, minibus services are often the only possibility for mobility. Despite the great importance of the mode, there is very little knowledge of routes, fares, and the number of minibuses. Hence, it is difficult to simulate and to understand the influence of this mode on other modes and on transport planning in general.. is article presents the development of the first "close-to-reality" minibus supply model based on demand and street network only The approach adopts the survival-of-the-fittest principle, using a co-evolutionary algorithm that is integrated into a microscopic multi-agent simulation framework The successful application of the approach to a large-scale, real-world scenario in the Nelson Mandela Bay Area Municipality in South Africa shows that it is able to identify the main minibus corridors as well as to find robust service coverage in lower-demand areas The resulting minibus supply model can then be used for planning purposes (e.g., to investigate aspects of strategic, operational, or regulatory changes)

Using multi-source GPS data to characterize multiday driving patterns and fuel use in a large city region

The paper describes the use of GPS data obtained from both commercial and project-specific sources to examine the travel behavior and fuel consumption patterns of drivers over a three-day period in Gauteng Province, South Africa. Data for commercial (truck and light delivery vehicle) traffic are obtained from a commercial fleet management provider, which continuously tracks the movements of 42,000 vehicles. Data for private car users come from a panel of 720 drivers, whose multiday driving activity is tracked using mobile passive GPS loggers. We analyze and compare the driving behavior of the two driver populations in terms of total distance travelled, spatial patterns (e.g. the amount of travel on different road types) and temporal variations (e.g. variations across time of day and across multiple days). The detailed nature of GPS data also permits the estimation of fuel consumption at a very disaggregate level (by link and time of day), and the identification of differences between user groups, which have significant implications for transport and energy policy. We introduce a new indicator, the recovery ratio, to assess the relationship of fuel use to distance travelled on different classes of roads, to help identify equity distortions across user groups. Lastly, we comment on research needs related to the collection and integration of GPS data from multiple sources for model calibration and program evaluation.South African National Roads Agency Ltd. (SANRAL)http://trb.metapress.com/content/0361-1981/hb201