Conference Proceedings (Civil Engineering)

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    A study to measure the accuracy of speed data reported by floating car data in rural areas
    (Stellenbosch : Stellenbosch University, 2023-03) Kiautha, Antony Mugambi; Bruwer, Megan; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: Intelligent Transportation Systems (ITS) technologies are becoming routine worldwide, offering newer methods of obtaining traffic data. Recently, on-board vehicle navigation devices have offered Global Positioning System (GPS) data spanning an entire road network referred to as Floating Car Data (FCD). The accuracy of FCD is critical to evaluate traffic information and inform stakeholders involved in transportation planning in different regions. This study was conducted to measure the accuracy of speed data reported by commercial FCD in rural areas. The study compared benchmark speed data and TomTom historical speeds on 12 rural routes and 7 urban routes in the Western Cape in South Africa. The benchmark data was provided by the Western Cape Department of Transport, collected through loop inductance. Data collected was analysed for weekdays (Monday to Friday) in the month of February 2019 and aggregated over 1-hour time intervals. This was done to give a true representation of traffic patterns and analyse traffic patterns before the COVID-19 pandemic. To evaluate accuracy, probe penetration rate, signed error bias (SEB), average absolute (AASE) and signed error were determined. The minimum probe penetration rate considered for accuracy measurements was 4% and the maximum allowable errors for SEB, AASE and signed error were ±7.5 km/hr, ±10 km/hr and ±10 % respectively. The SEB and AASE accuracy measures showed that FCD reported speeds were consistently lower in the urban areas while some routes in the rural areas recorded higher FCD speed estimate than the benchmark data. Probe penetration rates for both urban and rural areas indicated that a high probe penetration rate is not directly proportional to a high level of speed data accuracy. This study is relevant because evaluation of commercial FCD accuracy has not been examined in rural areas and it is an informative research to assist in improving the transportation industry across the globe and especially in developing countries.
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    Auditory intelligent speed adaptation for long–distance informal public transport in South Africa
    (IEEE, 2016-04) Ebot Eno Akpa, N. A.; Booysen, Marthinus J.; Sinclair, M.
    ENGLISH ABSTRACT: Informal transport refers to the collective passenger road transport industry with little or no regulatory control of its operations, usually characterised by unplanned and ad-hoc service delivery. The notoriously dangerous informal transport industry in South Africa – dominated by minibus taxis – has been shown to disregard the posted speed limit on long-distance trips. Not only do they frequently exceed the differentiated speed limit imposed on minibus taxis, but also the speed limit imposed on normal passenger vehicles. This paper evaluates the impact of an auditory Intelligent Speed Adaptation (ISA) intervention, applied at various intensity levels, on the speeding behaviour of this seemingly intransigent mode of transport. The experiment evaluates the behaviour on the R61 between Beaufort West and Aberdeen. We evaluate the speeding distributions, speeding frequencies, speed percentiles, mean speeds, and the statistical relevance of key metrics. We find that the auditory intervention has a clear impact on speeding behaviour, both when applied at an audible level that can be drowned out by a radio, and even greater impact at a loud level. The impact on speeding is significant, with speeding frequency (both time and distance) reducing by over 20 percentage points.
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    A quantitative measure of congestion in Stellenbosch using probe data
    (2014-12) Ter Huurne, Dominique; Andersen, Johann
    ENGLISH ABSTRACT: This paper aims to quantify and evaluate congestion in Stellenbosch, a historic university town located approximately 50 kilometres east of Cape Town, South Africa, using probe data. It is known that Stellenbosch experiences traffic congestion, but the scientific extent of this congestion has not been fully determined, as the present volume counts alone are not a sufficient form of assessment. Its residents complain about congestion suffered in town and express frustration. This, along with the fourth annual TomTom South African Traffic Index publication, which revealed that Cape Town (with a congestion index of 27%) is the most congested city in South Africa, instigated this study. Literature bares that the level of service concept (LOS) defined in the Highway Capacity Manual (HCM) has been widely used as a basis for congestion measures, although travel-time-based measures are suggested to satisfy the need for congestion information best. Travel time is well understood by both the general public and professional community, but the collection of travel time, travel speed, travel rate and travel delay data is historically deemed somewhat more complex and onerous than traffic volume counting procedures, and together with limited financial resources has restrained its application. The methodology applied in this study comprises the utilisation of TomTom Traffic Stats Portal that contains historic travel-time-based data from TomTom in-vehicle navigation systems and supporting devices. The platform and associated configuration is state-of-the-art and brings new light to travel-time-based congestion measures. The data was statistically analysed over various date and time periods, and standard congestion index concepts were applied. Congestion measures were considered along the major arterials leading into and out of Stellenbosch, as well as on part of its central road network. This paper shows that Stellenbosch evidently faces increased levels of congestion. Travel times on the inbound arterials are on the rise, and in-town traffic is becoming unsustainable.
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    Performance measurement trends in the implementation of Intelligent Transportation Systems (ITS) within the South African transportation environment
    (2014-12) Struwig, C. B.; Andersen, S. J.
    ENGLISH ABSTRACT: Over the past decade, the South African transportation environment has actively started to adapt a technology-driven setting. Intelligent Transportation Systems (ITS) applications such as Advanced Traffic Management Systems (ATMS) and Advanced Public Transportation Systems (APTS) have since been promoted and developed. These ITS deployments have brought about new areas for consideration. If the sustainability of the newly developed systems is to be ensured, sufficient attention needs to be given to the managing of their inherent technology-related aspects. These aspects are currently, to varying degrees, being measured and monitored. However, little thought is given to ITS performance management in the conceptualization- and planning phase of ITS projects. As a result, the monitoring is mostly done by a modular- and possibly inconsistent performance measurement approach. Moreover, in the absence of a set of widely accepted performance measures and transferable methodologies, it is very difficult for the local industry to objectively assess the effects of their specific applications with regard to the implementation of policies and technologies. The aim of this paper is thus to define a common evaluation framework for the monitoring and managing of the newly developed systems and to present guidelines as to its application. The aforementioned is accomplished by elucidating the need for managing performance measurement and by providing a review on the current ITS measurement trends and movements in the South African transportation environment. Ultimately, a major evolution in the nation’s transportation environment - in the form of an ITS performance management regime - may be stimulated.