69 research outputs found

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

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    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

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    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

    The survivability of cycling in a co-evolutionary agent-based model

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    DATA AVAILABILITY : The datasets generated and analysed during the current study are not publicly available because they constitute an excerpt of research in progress but are available from the corresponding author upon reasonable request.Many cities plan to grow cycling as a prominent mode to improve accessibility and environmental and financial sustainability. However, relatively few cities have made meaningful headway in this direction. Policymakers would be more inclined to implement the necessary interventions when they have certainty about potential demand, especially knowing where it is located in space. This paper introduces an approach to estimating potential cycling demand using agent-based modelling to determine who may benefit from switching from their current modes to cycling. People benefit when they obtain a similar or higher travel utility score when cycling between their daily activities than when using their existing modes. The model is based on individual mode selection, that all activities in the trip chain are included and can include detailed road and cycle network elements. The co-evolutionary mechanisms within the agent-based simulation allow us to test the potential for cycling relative to the performance of other modes on the network. The case for Cape Town, South Africa, shows that about 32% of those that travel would benefit from cycling based on their utility score. Understanding that travel time benefits are not the only criteria for mode selection, we apply a rejection sampling algorithm based on demographic factors to demonstrate that a more realistic, or pragmatic, cycling potential for Cape Town is in the region of 8%. The results also show that more than 46% of the observed pragmatic demand for cycling is concentrated in an area covering less than 7% of the study area. This has practical implications for policymakers to target interventions both in space and towards specific demographic market segments.https://link.springer.com/journal/11116hj2024Industrial and Systems EngineeringSDG-09: Industry, innovation and infrastructureSDG-11:Sustainable cities and communitie

    Testing self-perception theory with agent-based simulation

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    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

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    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

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    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

    Impact of road grade on the risk profile of driver behavior

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    Data generated from telemetry devices, such as acceleration and speed, are used in a variety of industries to determine the risk profile of a driver. This paper considers the addition of road gradient as a contextual variable to a driving behavior model to determine specifically if the risk of a driver is influenced by different road grades. This behavioral risk is demonstrated by comparing the performance of heavy vehicle drivers with and without the addition of road grade as a variable. This is done by using accelerometer data of 48 heavy goods vehicles over an entire month, and appending elevation data from digital elevation model (DEM) data, specifically that of the Shuttle Radar Topography Mission (SRTM), to the vehicles’ GPS traces. The elevation values are used to calculate road grade values which are then categorized in five grade levels. The results show that there is a clear influence of gradient on the behavior of the drivers studied. There is also evidence that steeper sections on a road can cause a change in an individual’s performance when compared with the group.The Waste RDI Roadmap, funded by the Department of Science and Innovation.https://journals.sagepub.com/home/trrhj2024Industrial and Systems EngineeringSDG-09: Industry, innovation and infrastructur

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

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    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

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    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

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    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
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