Conference Publications

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3D physical model study for proposed remedial works to the Port of Richards Bay breakwaters
(2024-04) Wehlitz, Carl-Peter FV; Mabille, Eugene
The Port of Richards Bay is frequently subjected to extreme storm events where recorded wave heights can easily exceed five meters. Over the last two decades, these storms have caused significant damage to the port’s breakwaters. A 3D physical model study was commissioned with the objective to assess and verify the stability of four different strategies to repair and enhance the structural integrity of these structures. Results from this study showed that both breakwaters will ultimately fail if no major improvements to these structures are made. The repair options tested for the main breakwater included a comparison of two different toe designs, as well as comparing the performance of two different armour unit types. The outcome indicated that the repairs to the main breakwater will most likely entail a trenched toe design and an armour layer comprising of very large cubic-type blocks. While the repair options tested for the lee breakwater mostly entailed placing additional or larger armour units of the same type, it did allow the opportunity to optimise both the armour unit size and the coverage for an improved overall outcome.
3D Physical model study for the Haifa breakwater retrofit design
(2024-05) Wehlitz, Carl-Peter FV; Somlota, Lukhanyo L
Since the original designs were performed without current wave forecasting data that accounted for climate change and sea level rise, the Port of Haifa is becoming more frequently subjected to extreme storm events. These storms have caused major damage to the port’s main breakwater, and the rock used in the 1930 vintage portion of the structure has deteriorated. A 3D physical model study was commissioned with the objective to assess and verify the stability of a retrofit design proposed to enhance the structural integrity of the main breakwater. The design included major modifications to the structure, with the most prominent being a new armour layer. This would result in the widening of the breakwater, as well as raising the crest. Results from this study showed that a single-layer Cubipod armour layer would be sufficient to cope with the extreme conditions tested. A variation to the design was, however, required at two sections of the breakwater where World War II vintage historic fire command towers are located. This is because design restrictions prohibited any alterations to these towers and the adjacent crest areas. The variations included a milder seaward slope, as well as constructing a double-layer armour layer at these locations.
An examination into prospective research areas concerning the safety of learner transport, specifically focusing on intentional harm
(2024) Rathogwa, Mashudu
The focus of this presentation was to highlight potential strategies for addressing the current deficiencies in research and practical actions aimed at strengthening school security procedures.
An examination into prospective research areas concerning the safety of learner transport, specifically focusing on intentional harm (Conference Paper)
(2024) Rathogwa, Mashudu
In South Africa, as of 2018, the alarming statistic of one child being abducted every five hours highlights a pressing concern for the safety of school children. What compounds this issue is the stark inadequacy of school security procedures in place to thwart potential abductions. Criminal syndicates, notorious for their meticulous and thorough operations, often exploit schools by infiltrating them under the guise of concerned parents. Kidnappings and abductions cut across socioeconomic boundaries, impacting both the underprivileged and affluent segments of society. The motives of these kidnappers encompass physical violence, financial exploitation, and even the gravest outcome, murder. In response to this disturbing trend, this research aims to highlight the existing gaps in both the research and practical measures that can be taken to fortify school security protocols, ultimately ensuring the safety of learners against kidnappings and abductions.
Analytical techniques to quantify modifiers in bitumen for the South African asphalt pavement industry
(2021-07) Makhari, A; Hawes, Nomashaka BN; Mturi, George AJ; Ojijo, Vincent O
Modifying bitumen is currently a common practice in South Africa. The asphalt pavement industry has seen an increase in use of different types of modifiers in an attempt to improve or extend the properties of bitumen. Common modifiers used in South Africa include plastomers (e.g. ethylene vinyl acetate or EVA), elastomers (e.g. styrene-butadiene-styrene or SBS) and warm mix additives (e.g. waxes). Bitumens are already complex materials which can be represented mechanically and rheologically with mathematical models. Recently, the need to also characterise the in situ structural and chemistry effect of modifiers within bitumen has been appreciated, in order to determine their influence on modified bitumen performance. This paper explores the analysis of bitumen with various modifiers using Fourier Transform Infra-Red (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC). Special attention is paid to quantification of these modifiers in bitumen as a quality control and forensic investigative tool, due to the current asphalt failure challenges facing the industry. The aim is to accurately determine the extent of modification through analytical techniques as a monitoring tool for the better construction of asphalt pavement roads. The paper shows such analytical scientific techniques have the potential to quantify locally used modifiers in South African bitumen.
Application of drones and image processing for bridge inspections in South Africa
(2021-07) Kemp, Lana; Roux, Michael P; Kemp, Mauritz J; Kock, R
In South Africa, visual inspections for all bridge structures are required every five years. A need was identified to establish if it would be practical to utilise technologies, such as drones and photogrammetry, to improve inspections and to reduce the cost of inspections. Drone and photogrammetry technologies are large components in the Fourth Industrial Revolution (4IR). For proof of concept, two bridges were inspected us-ing a drone. The drone inspection data captured for the two bridges was processed and point cloud models were created. These point cloud models were then used to estab-lish whether defects, identified on these bridges previously by way of regular TMH 19 visual assessments, could be identified from the point cloud models. The outcome of the study showed that it would be possible to use processed images from drone in-spections or other image capturing methods to inspect bridges and for monitoring pur-poses. The use of these technologies could improve the inspection methodology, not only of individual structures, but also of a network of structures as required by road au-thorities. Recommendations are made for future work.
Best practices in support of vulnerable road user protection in South Africa
(2023-07) Barnard, HC; Venter, Karien
Vulnerable road user fatalities continue to make up the bulk of road traffic related deaths in South Africa. Safe System-based measures aim to improve the safety of the road environment for all road users including vulnerable road users. Safe System-based measures are primary mitigation measures that focus on reducing the severity of accidents while supporting techniques and measures that focus on reducing the number of accidents. Road Restraint Systems (RRS) form a vital part of the road planning and design process in support of minimising the severity of accidents, including accidents involving vulnerable road users. The uptake of best practices relating to the provision of safe and forgiving roads that can mitigate the severity of injuries in South Africa, has been poor. This research paper considers the plight of vulnerable road users in the South African road environment and provides practical evidence/examples of existing scenarios where roadside risk for vulnerable road users such as non-motorised transport users can be addressed through the provision of correct and crash tested RRS that contribute to making the road environment inherently safe and more forgiving.
Bridge CNN defect prediction models using existing image data
(2022-11) Kemp, Lana; Roux, Michael P; Steyn, WJvdM
In South Africa, it is a requirement for all road agencies to conduct principal visual inspections of all bridge structures every five years. Smaller municipalities do not always have the necessary funds available for principal bridge inspections, resulting in either bridge inspections not being executed, or inspections being done by unqualified people. This paper intends to investigate the possibility of using existing bridge inventory and inspection image data to develop Convolutional Neural Network (CNN) models to predict and classify bridge defects autonomously. This research aims to improve the quality of bridge inspections and condition ratings assigned to defects to be more consistent and not reliant on human subjectivity. These models could ultimately be used for quality control in a Bridge Management System (BMS). The CSIR STRUMAN BMS contains inspection and inventory images captured during principal visual bridge inspections. As a proof-of-concept, bridge roadway joints were considered. 600 images of bridge roadway joints captured in the system were classified according to Defect and No Defect datasets. Different CNN classification models were developed to predict whether an image of a bridge roadway joint contained a defect or not. The image datasets were used to train, validate, and test the performance of the CNN models. The performance of the CNN models was evaluated using a Confusion Matrix and Classification report to select the best-performing model. In conclusion, the selected model was evaluated when introduced to new unseen images. The best performing CNN model utilised transfer learning and data augmentation to predict with 95% accuracy from images if a bridge roadway joint had a defect and with 65% accuracy if the bridge roadway joint had no defect.
Combining bio-based cementation with cement stabilisation for road construction
(2024-07) Smit, Michelle A; Rust, FC
The growing concerns over climate change and the move towards sustainable, costeffective road development have resulted in the development of bio-based construction methods. Microbial induced calcium carbonate precipitation (MICP) binds material through the formation of calcite bridges between soil grains. Current MICP treatment techniques, however, are not compatible with road construction processes. Due to this the Council for Scientific and Industrial Research (CSIR) has started investigating bio-stabiliser treatment techniques for road construction. The objective of this paper is to present Unconfinded compressive strength (UCS) results for a G8 material stabilised using in-situ bacteria present in the soil. After 10 days of cementation solution treatments a UCS dry result of 1.16MPa was achieved. No wet UCS results were, however, produced as all the samples disintegrated. The decision was made to supplement MICP with 0.7% cement. Not only did UCS wet results show a 100% increase compared with MICP only treated samples, but the UCS dry results were comparable to adding 2.5% cement to the G8 material. Partial replacement of cement with MICP during stabilisation could lead to an overall reduction in the amount of cement used in road construction without compromising strength, which will have a positive environmental and economic impact.
Community perspectives as an essential element of resilience thinking: Resilience from a view of inequality
(2020-12) Dlamini, Sifiso B; Meyer, Isabella A
Resilience is a popular concept in development studies, particularly in research and development on how Information and Communication Technologies (ICTs) can be used to improve livelihoods. As much as the primary focus is on using ICTs to deliver services in sectors that operate in resource constrained environments, the question of inequality remains a key consideration. One of the challenges that faces the future of the ICT-related development of communities is the perspectives and perceptions of researchers on communities, particularly in developing countries with remote rural areas. Taking a resilience view on community without addressing the question of inequality leads to biased resilience strategies in the rural communities of developing countries. This paper presents thinking from an ongoing research study that aims to develop a resilience framework and guidelines for the introduction and use of mobile technologies in South African rural schools.
Conceptualising a benefit assessment framework for the South African National Roads Agency Ltd SOC research and development programme
(2021-09) Rust, FC; Sono, P; Van Dijk, G G; Fourie, H; Smit, Michelle A
In low-income countries Research and Development funding is limited and has to be invested with a view of optimum return, both economic return but also “softer” benefits such as human resource development. The assessment of these benefits is therefore important for the long-term sustainability of research and development programmes. Outputs from research and development in roads and transport are often not hard products aimed for the consumer market, but also include new design methods and techniques to enhance the performance of the transport system that cannot be easily quantified with benefit cost analysis alone. The article discusses the development of a framework for the monitoring of the performance of the South African National Roads Agency Research & Development Programme. The framework consists of a Balanced Score Card and a proposed set of indicators that address benefit throughout the innovation value chain.
Creating pathways to impact: Investing in supply chain and logistics capacity development in Africa
(2023-03) Grobbelaar, S; Meyer, Isabella A; Van Eeden, J; Vandaele, N; Van Wassenhove, L; Besiou, M; Decouterre, C; Rafter, S; Nolting, C; Dondofema, Richmore A
African logistics and supply chain management capabilities are essential to the performance of the continent's commercial and humanitarian supply chains. This study reviewed the challenges for researchers and practitioners in advancing logistics and supply chain performance through developing appropriate capabilities. A literature review and landscape mapping were followed by semi-structured interviews with 45 stakeholders from industry bodies, academia, funding bodies, consultants, specialists, and academics, confirming the capability and opportunity gaps in the current landscape. A meta-framework for sustainable institutional capacity development was constructed based on the empirical data that was gathered, and supply chain capacity development recommendations were proposed.
Design approach for the access channel of Port Victoria, Seychelles
(2024-04) Terblanche, L; Rossouw, M; Troch, Christophe NA
Existing spatial and infrastructural limitations of Port Victoria and its potential effect on Seychelles' economy have made the expansion of the port essential for future development. To accommodate postPanamax container vessels and fuel tankers with static drafts of up to 14 m, the port basin and access channel must be expanded and deepened. The design approach for the new access channel comprised: an assessment of the existing vertical and horizontal channel dimensions; a conceptual design, based on empirical channel design guidelines; and a detailed probabilistic assessment using ship motion and navigation simulation models. Fast-time navigation simulations were conducted and supplemented with real-time simulations. The navigation simulation data were statistically analysed to confirm the alignment and horizontal dimensions of the access channel. The vertical dimensions of the channel were determined by a vertical response analysis of the design vessel to ensure sufficient under-keel clearance while transiting the channel. The use of modelling and simulation proved to be valuable in refining the dimensions necessary for the safe navigation and manoeuvring of the proposed design vessels. These dimensions informed the dredging requirements for the project.
Developing a truck rollover risk calculator for South Africa
(2022-07) Ferreira, A; De Saxe, C; Steenkamp, Anton J; Nordengen, P
The Static Rollover Threshold (SRT) is an important metric for characterising a heavy vehicle’s inherent stability and risk of rollover. Current methods of assessing SRT include a tilt-table test and multi-body dynamics simulation which can be costly, time-consuming and often require significant technical expertise or technical vehicle data not normally accessible to the public. Simplified calculation methods exist, but a remaining challenge exists to reduce the required level of user expertise and input data to make the assessment useable by, for example, fleet insurers who would have an interest in SRT information. In this paper we investigate the use of simplified calculations prescribed by the New Zealand Land Transport Rule (NZLTR) and UNECE 111 as the basis for the development of a user-friendly SRT calculator. The calculation results were validated against a multi-body dynamics model using TruckSIM for the case of a rigid truck for a range of vehicle suspension and mass properties. The NZLTR and ‘interpolated’ UNECE 111 methods resulted in the smallest errors compared with TruckSIM, averaging 6-7% in absolute error over the 16 scenarios assessed. Maximum errors occurred when the ratio between drive axle and steer axle roll stiffness was at its highest (at a ratio of 4.7:1). The UNECE 111 method was then used as the basis for a Python-based SRT calculator tool. The tool demonstrates how pre-loaded technical vehicle data and logic can be used to minimise the required user expertise and hence make SRT calculation feasible by non-technical users in the fleet insurance industry in South Africa.
Development of a geospatial database of MBT ranks: LoS categorisation of facilities in Gauteng
(2024-07) Mhlanga, Shaun L; Akinnusi, O; Bosilong, Keolebogile K; Malandela, Gcina; Malope, Retang K
The transformation of local and township economies has been identified as one of the critical areas for the government's medium-term socio-economic developmental aspirations in Gauteng. Further, recent Gauteng household travel surveys have acknowledged the significant role of Minibus Taxis (MBT) in commuting most commuters daily and account for a substantial proportion of peak traffic demand. This paper contributes to the evaluation and categorization of public transport facilities research by advancing the development of a weighted decision tool that can assist urban and transport planning authorities to better identify and prioritize areas for improvement and maximize investment when upgrading the quality and level of service provided to MBT commuters. The focus of this paper is based on a) the development of MBT facilities GIS database based on primary data collection; and b) the synthesis of academic research on public transport facility evaluation, and Gauteng draft policy guidelines on MBT and bus facilities to facilitate analytical and functional categorisation of MBT ranks based on prescribed level of service. Evaluation and categorization of MBT facilities (ranks) can assist the prospective guideline policy of developing ranks to become economic hubs that can support innovative solutions to creating jobs, modernization, and formalization of the broader township economy.
Difficulties monitoring short-term ageing in thin surfacing layers using asphalt concrete
(2024-07-20) O'Connell, Johannes S; VdM Steyn, WJ; Maina, J
Ageing has a profound effect on pavement performance, especially regarding cracking. Due to budgetary constraints, South Africa has pioneered the use of thin asphalt concrete layers. The research described in this paper is based on a short-term ageing study in South Africa, using data generated over a period of 6 years. During this time, polymer modified asphalt binders were increasingly employed in road construction, and rheological analyses from the dynamic shear rheometer were increasingly used to characterize asphalt binders. This study compared the complex shear modulus to the softening point as an ageing index property used to monitor the extent of short-term ageing of the recovered asphalt binder from newly laid asphalt concrete. The asphalt binder properties from 20 constructions sites were evaluated, whereby the recovered binder from the site shortly after construction was evaluated against the asphalt binder properties obtained in the laboratory after the rolling thin film oven treatment. The results indicate that the recovery process leads to a deterioration in the repeatability for the complex shear moduli obtained from recovered asphalt binders. The lower repeatability prevents meaningful conclusions from being made. Furthermore, the work shows that although the Rolling Thin Film Oven Test may be a good predictor of short-term ageing when using softening point as an ageing index property, it is only valid for unmodified asphalt binders in South Africa.
Driver perception of fluorescent yellow green signage
(2024-10) Marole, Busisiwe C; Bosilong, Keolebogile KJ; Mongae, Tshegofatso; Cheure, Namatirai; Venter, Karien
The Safe System Approach (SSA), to which South Africa is a signatory, is the premise of the South African National Road Safety Strategy (SANRSS) that aims to significantly reduce the number of road traffic fatalities and severe injuries. It recognizes that human error is inevitable and seeks to minimize the consequences of mistakes by designing roads, environments, vehicles, and traffic systems that are more forgiving. Road signs play a critical role in ensuring the safety of both motorists and pedestrians on roadways. International evidence points to the fact that among the various colours used for road signage, “fluorescent yellow green (FY/G)" or "safety yellow," stands out as a colour that commands attention. FY/G signs has emerged as an effective and attention-grabbing colour to highlight hazardous locations and conditions. FY/G is vibrant and highly visible appearance, especially in adverse weather conditions and low-light situations. However, it is currently not part of the South African Road Traffic Signs Manual (SARTSM), which is the guiding regulation for the application of road signs in South Africa. A pilot study was undertaken for South Africa, to measure the perception of FY/G for South African drivers. This extended abstract provides feedback regarding the preliminary findings in support of the use of FYS signage as part of the South African road environment.
Enhancing safe mobility using inclusive intelligent infrastructure management system
(2024-07) Abejide, Samuel O; Adedeji, JA
In the dynamic realm of urbanization, smart city development, particularly in relation to transportation infrastructure, is gaining momentum. This study addresses a gap in the current strategies by emphasizing effective management over mere expansion. Managing infrastructure systems is essential given the increasing trend of tech-driven transportation and the vehicle-to-capacity ratio. To maximize the current infrastructure in East London, South Africa, the Inclusive Intelligent Infrastructure Management System (IIIMS) is the suggested solution. For more sophisticated transportation system design, the project combines data-driven approaches with intelligent transportation systems (ITS). Demand management, predictive maintenance, route optimization, and real-time data collection are important components of this approach. By offering information on traffic patterns, hotspots for congestion, and possible conflicts, these initiatives support well-informed decision-making for capacity expansion. Focusing on Oxford Street, a congested area in East London, this research employs the smart city wheel and the 15-minute smart city concept. The IIIMS loop incorporates adaptive hypotheses for safe mobility principles in a specific spatial and temporal context. By examining the elements of an inclusive intelligent transportation system, this study considers telematic technologies, data-driven traffic management, and safe mobility principles. Hypotheses related to private vehicle access, worker safety, citizen well-being, and urbanized infrastructure management are discussed, offering solutions for safe mobility. The proposed framework includes an operational level-of-service (LOS) lane change modification for Oxford Street, promoting flow and reducing congestion. Recommendations should focus on competitive measures for delay-time management, congestion patterns, and hotspot identification, contributing to smart city discourse and emphasizing inclusive intelligent infrastructure management for safe mobility and urban transportation competitiveness.
Evaluating the efficacy of laboratory ageing of asphalt mix binders as a prediction for field ageing
(2023-10) O'Connell, Johannes S; Maina, J; Bredenhann, SJ; Marais, H; Komba, J
A Performance-grade Binder Specification (SATS 3208) for South Africa was finalised after CAPSA 2015 and launched at CAPSA 2019. A key feature of the performance-graded binder specification is the regulation of binder performance after long-term ageing, which is simulated in the laboratory using the pressure ageing vessel (PAV). This paper reports how this simulated long-term ageing relates to the ageing of binders in continuously-graded asphalt surfacing mixes in the field. Samples of asphalt surfacing mixes were obtained from ten sites in Gauteng, South Africa, which were constructed 5 to 30 years ago and selected based on the availability of the original binders. An ageing profile was developed for the original binders by characterising their rheology in the original state, after rolling thin film oven (RTFO) ageing and pressure ageing vessel (PAV) ageing after 20 hours, 40 hours and 80 hours. The ageing profiles were compared to the corresponding recovered binders. Rheological parameters used for comparison were Softening Point and Flexural Creep Stiffness / m-Value from the Bending Beam Rheometer (BBR) test.
Evaluation of interlayer bond strength for C55 emulsion prime bituminous binders with aggregates
(2024) Abejide, Samuel O; Pitso, Reatile I
The use of an environmentally and green friendly product for improved interlayer bond strength in recent times has gained interest in the construction industry. This study investigates the performance of the C55 Emulsion Prime when compared with the conventional MC30 prime in enhancing interlayer bond strength and overall adhesion potency with aggregate particles. The C55 Emulsion Prime is a bituminous-based binder designed to penetrate aggregate layers creating a cohesive bond that improves structural integrity and adhesion potency of the binder with aggregates. Through a series of laboratory tests conducted on the two samples, the study provides detailed results on the penetration depth, interlayer bond strength and application under wet conditions. The test results indicated that the C55 emulsion prime significantly enhanced interlayer bond strength with the G1 dolerite aggregate with notable improvement to moisturized or wet surfaces. The C55 Emulsion Prime demonstrates superior interlayer bond strength compared to MC30 Cutback Bitumen Prime in wet regions or when dry aggregate condition is not feasible. The C55 Emulsion prime has a rapid curing rate within 60mins of application to a wet surface making it an efficient protective layer over granular surfaces to adhere and form a good bond strength property with the asphalt layer. This superiority is evident in both the direct shear test, rolling bottle tests, penetration power test and Zeta Potential test making C55 Emulsion Prime a more reliable choice for enhancing pavement performance in accordance with environmental friendliness and climate change sequences. Furthermore, the adhesive strength of the emulsions can be determined by identifying the isoelectric point (IEP). IEP is the pH condition where the surface charge = 0 mV. The IEP of C55 is approximately at pH 4.1. The IEP of the MC30 has been extrapolated to be approximately at pH 2.1. Material where the IEP is at higher pH form the strongest bond because they have a high proton acceptability. It can be predicted that the C55 forms a stronger bond with the aggregate when compared to MC30.

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