Masters Degrees (Civil Engineering)

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Application of real-time traffic adaptive signal control on the R44 arterial, stellenbosch
(Stellenbosch : Stellenbosch University, 2019-12) Mohr, Wilko Stefan; Bruwer, Megan; Andersen, Johann; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
ENGLISH ABSTRACT: The ever increasing level of traffic congestion experienced within and surrounding the town of Stellenbosch, South Africa, has been one of concern for many years. A large volume of commuter traffic creates a major influx of vehicles into and through the town during the morning peak traffic hour and, vice versa, a large outflow during the afternoon peak hour. These extensive traffic volumes exceed the provided capacity, thus creating an imbalance relating to the capacity vs demand ratio. This in turn leads to extended travel times, increased vehicle delay and a general inconvenience to the typical road user. Considering this and understanding that congestion has a negative effect on the individual road user as well as on the economy in general, this research project investigates the potential feasibility of using a Traffic-Adaptive Signal Control (TASC) system to optimise and manage the flow of vehicles through a series of signalised intersections. Such a system relies on real-time traffic data input and a representative traffic model which simulates and tests several signalisation options and, based on the objective function of the optimisation method, results in a more suitable allocation of green-time shares within the network. This, in essence, optimises the flow of traffic on individual intersection level while at the same time coordinating the traffic flow on a network level. The main objective of this research project, therefore, was to evaluate the applicability of a TASC system on the R44 arterial surrounding Stellenbosch in order to address the question of how applicable and effective TASC is in a developing world environment as a means to alleviate transport related problems on a traffic corridor. PTV Epics and Balance, proven to be successful in developed world application, is one such TASC system and was used within this study to address the research question. In order to realise useful results, a calibrated and validated simulation environment had to be created. Modelling was firstly done within PTV Visum to create an underlying macroscopic model of Stellenbosch in general, after which another PTV Visum subnetwork model of the R44-specific study area was generated. The final model, a PTV Vissim microscopic model, represented the evaluative environment within which detailed results could be obtained for a number of different scenarios. These scenarios where firstly aimed at identifying whether the TASC system would bring any improvements at all and secondly under which level of TASC control, inclusive of different vehicle detection options, the best results were obtained. Different levels of TASC control refer to exclusive local optimisation, exclusive global coordination or a combination of both. Detection options included a suboptimal layout of the existing inductive loop detectors as well as more consistent TrafiCam x-stream virtual loop Results comparison over a range of traffic flow parameters showed that the TASC system did indeed enhance the traffic flow. This was most notably found to be true under condition of the consistent camera detection and, predominantly, by using combined local and global TASC control. Based on the findings, this study recommends, with further study and continued expansion, the implementation of the TASC system on the R44 arterial, Stellenbosch.
The economic evaluation of a bicycle-sharing scheme for school and university destined commuter traffic in Stellenbosch, South Africa that is proposed as a sustainable mode of transport to relieve traffic congestion: A case study for the R44 inbound traffic from Somerset West
(Stellenbosch : Stellenbosch University, 2016-03) Ter Huurne, Dominique Andrea; Andersen, Johann; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
ENGLISH ABSTRACT: The traffic congestion problem in the university town of Stellenbosch, South Africa is felt by a prodigious share of its residents and commuters on a daily basis. A quantification of the status quo verified that there are simply too many vehicles on the extended Stellenbosch road network at specific hours of the day (i.e. the demand surpasses its capacity), and that long-term growth cannot be withstood. The greater part of intersections on the main roads operate at a Level of Service F, and in most instances, all probable alternative routes to a driver do not bestow any significant gain in terms of travel time and / or delay. The Stellenbosch Municipality is one of the fastest growing municipalities in the country, and peak-period traffic congestion will spread over a longer time span if capacity problems remain unresolved. Within this context, this research project proposes bicycle-sharing as a congestion-relief measure that is believed to be ‘smarter’ and more sustainable than the standard roadway capacity expansion actions. This project is an economic evaluation of a theoretical bicycle-sharing scheme for school and university destined commuter traffic in the town of Stellenbosch, with the traffic congestion along the R44 from the Somerset West direction selected as the case study. By definition, bicycle-sharing is a nonmotorised mode of transportation (NMT) for short-distance, point-to-point trips in which bicycles are made available to users on a ‘sharing’ basis. The Stellenbosch Municipality is making progress in the development of the NMT network in Stellenbosch, but whilst the efforts, no doubt, have the potential to reduce traffic congestion, they neglect the many road users with out-of-town origins and destinations. The results of an electronic questionnaire distributed to Stellenbosch school-learner parents and Stellenbosch University (SU) students and staff, in fact, revealed that the main barrier preventing these road users from making use of active transportation is that the travelling distance is too long. The proposed bicycle-sharing scheme, which is to be operated from Drop-and-Go zones (scholars) and Park-and-Rides (SU students and staff), extends NMT to these commuters. The primary objective of this research was to evaluate the economic viability of the scheme. The secondary objectives were (1) to determine the first-order benefit and cost estimates of the scheme in the form of a Net Present Value, Benefit-Cost Ratio and First Year Rate of Return, and (2) to conceptually design a premier bicycle-sharing scheme for Stellenbosch and its school and university destined distance-travellers, so as to attain high, but still realistic, values for the economic parameters. The benefits were divided into direct benefits to the users, and indirect benefits to society and the authorities. The research design comprised (1) survey-based research to identify the number of potential users per road-user group (scholars, SU students and SU staff) and their barriers to cycling, and (2) evaluative research to appraise the costs (capital, launch and implementation, as well as operating and maintenance costs), benefits (mobility, health, safety and environmental improvements) and revenue potential. The conceptual design for which the economic evaluations were performed, proposes an automatic system for which the smartphone is to be the key component. The bicycle-sharing alternative and a geometric-improvement alternative (capacity enhancement at the R44 / Van Reede intersection) were tested against the null alternative: a continuation of the existing conditions with no money invested for upgrades. Various scenarios were analysed for the bicycle-sharing alternative, relating to scheme size, ridership, fare structure and operational model modifications. A traffic demand model, i.e. a simulation, was created as part of the evaluative research (using self-conducted traffic volume counts as the input), which determined the vehicle miles travelled, vehicle hours travelled and mean system speed for each alternative and scenario. These parameters served as the input to the vehicle-operating-cost, travel-time and CO2-emission travel-cost (and eventual travel-costsaving) equations. Probe data was used to calibrate the model. For the three road-user groups scholars, SU students and SU staff, 358, 490 and 241 potential bicycleusers were identified according to specified criteria, respectively. On the whole, it can be confidently stated that bicycle-sharing is an economically viable affair for the study area. First year rates of return ranging from 0.23 to 0.88 were determined for the scheme that was believed to have a total service life of 15 years, and benefit-cost ratios between 1.38 and 9.98 were computed for the future bicycle-share users. Whilst the geometric-improvement alternative was found to be economically viable, many of the appraised bicycle-sharing scenarios were learnt to be more so. At a time and place where the resources for a state-of-the-art public transit system are absent, bicycle-sharing is hence considered to be the front-runner in terms of congestion-relief measures. Championing the scheme is vital for its success, and the importance of it may, by no means, be underestimated. Further research should look into the benefits that are achievable on other Stellenbosch arterials, and hence determine to which extent bicycle-sharing can relieve traffic congestion on the wider Stellenbosch road network.
Economic evaluation of a fully integrated intelligent transportation system in Stellenbosch using the tops-bc tool
(Stellenbosch : Stellenbosch University, 2017-03) Dany, Olish Akas; Andersen, Johann; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
ENGLISH ABSTRACT: Transportation plays a fundamental part in the social and economic functioning of a society, since it permits the movement of individuals and products to their destination. A reliable transportation system significantly affects the economic vitality of a nation and its capacity to make use of its natural assets. Cities have considerably improved their transportation system in order to ensure the availability of transport facilities. Transport issues, specifically, traffic congestion and road safety cannot be solved by the construction of new road infrastructure, which in themselves have high time and cost implications. For this reason, various components of Intelligent Transportation Systems (ITS) are considered as innovative alternative solutions. The objective of ITS is to improve road traffic conditions using modern technology, which empowers transportation management and operations to ensure road safety and efficiency using existing road infrastructure. ITS may not totally eradicate traffic congestion in Stellenbosch, but provide a fundamental parts that can yield more operational effectiveness from the current transportation network. It is a challenge to estimate the impacts of the ITS applied to the Stellenbosch transportation networks, because benefits from ITS deployments in the greater South Africa are poorly studied and understood as these technologies are still fairly new. Stellenbosch currently has no formalised public transport system. The informal minibus taxi services mainly cater for the low-income residential areas and farm workers. Like various urban communities in South Africa, Stellenbosch still battles with the remnants of apartheid's spatial arranging structures and racial isolation, which created spatial disparities of access for various races. Poor communities exist on the edges of the urban areas and force them into long commutes to work and school, while pedestrian facilities and/or public transport are inadequate. Stellenbosch also caters for the mobility of a large student population, tourists and business entities, resulting in major traffic congestion problems. The objective of this study is to provide an understanding of suitable ITS applications for Stellenbosch, by quantifying the benefits and costs that will result from the deployment of specific components of integrated ITS and operational strategies in Stellenbosch. There are different procedures to determine Benefit-Cost (B/C) ratios, but this thesis makes use of the Tool for Operations Benefit/Cost (TOPS-BC) that was developed by the Federal Highway Administration (FHWA) of the United States of America (USA). TOPS-BC is a spreadsheet-based tool intended to help practitioners in evaluating the advantages of operations or ventures. The B/C evaluation in this thesis compared ITS operations and deployment scenarios to a more conventional scenario that contain no ITS operation and deployment. TOPS-BC was intended to assess the particular benefits and costs of ITS deployments based on observed, real–world benefits and costs. It was used to gauge benefits, incorporating changes in travel time, travel time reliability, number and severity of accidents, vehicle emissions, fuel usage, and other essential measures. The ITS facilities that constitute the Stellenbosch ITS deployment were identified from information provided by the local Stellenbosch Municipality Transportation and Planning Department. Data was extracted from the Stellenbosch mobility study, which was carried out in 2010. To achieve the research objective two scenarios were tested. Firstly, to estimate the ITS deployment benefits in Stellenbosch, the following ITS operational strategies were analysed with TOPS-BC:  Arterial Traffic Management System  Parking Management System which is an application of En-Route Multimodal Traveller Information System Secondly, the construction of the Stellenbosch Western Scenic Bypass was proposed as a traditional transportation strategy. This was evaluated and compared with abovementioned ITS operations strategies. The overall B/C results indicate that the deployment of the proposed ITS strategies of the Stellenbosch Arterial Management System and the Stellenbosch Parking Management System yielded higher B/C ratio, compared to that of Stellenbosch Western Scenic Bypass. Based on the assumptions of the research, it will be more beneficial for Stellenbosch Municipality to deploy these ITS strategies, than to have a roadway bypassing Stellenbosch.
Investigating the sustainability of the freeway management system and feasibility of implementing a connected vehicle environment in the Western Cape : conceptual design of a connected vehicle environment in Cape Town
(Stellenbosch : Stellenbosch University, 2017-03) Kriel, Aadil; Andersen, Johann; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
ENGLISH ABSTRACT: Please refer to full text for abstract
Pre-signal study at an at-grade intersection with separate right-turn phase
(Stellenbosch : Stellenbosch University, 2015-03) Tang, Hao; Andersen, Johann; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
ENGLISH ABSTRACT: Capacity waste happens when right-turn vehicles have right-of-way during a separate right-turn phase and lanes (e.g., through lanes) of the same approach of the intersection cannot discharge vehicles during that green phase. Right-turn traffic consumes the capacity which otherwise could be provided to through traffic movements at an at-grade signalized intersection. Therefore, it is widely considered that it would lower intersection capacity and increase total delay (Lin, Machemehl, Lee & Herman, 1984). The pre-signal strategy proposed in this research is specifically designed to improve this problem. The following aspects of this strategy were studied in this research, - Capacity benefits of this strategy, - Relationships between the capacity and the length of sorting area (the area between the two signals), - Signal timing of both main signal and pre-signal, - Clearance time of the sorting area, - Main signal phasing options - Signal coordination between the main signal and the pre-signal, - Utilization of the sorting area, and - Pre-signal strategy performance in a simulated environment. The results of this study showed that right-turn movement benefits significantly from this pre-signal strategy. For example, right-turn capacity can be doubled if a presignal is installed on one through lane of an approach with one right-turn lane. It was also found, the maximum approach capacity benefit is not affected significantly by the length of the sorting area for a given green period. The optimal green time and the available pre-signal green time for right-turn movement were also derived in this research. Different main signal phasing options were studied and compared. Phasing options which fit the proposed pre-signal strategy were found. Recommended values for right-turn green time of both signals were given based on different lengths of sorting area. The case study, which compared the performance of some critical movements at the intersection with and without the proposed pre-signal system, confirms the results concluded in this study. A potential problem with this strategy when applied at a real intersection is that it may confuse drivers. Drivers need to be educated and will need time to get familiar with this signal control method.
Validation of TomTom historical average speeds on freeway segments in Gauteng, South Africa
(Stellenbosch : Stellenbosch University, 2017-03) Gwara, Batsirai; Andersen, Johann; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
ENGLISH ABSTRACT: Traditional methods of traffic data collection, such as inductive loops and road sensors, continue to be the main source of traffic data. The advancement in technology and vehicle tracking methods has proved to be the impetus behind the emerging of alternative and innovative sources of traffic data, such as ITS data sources. ITS sources, such as vehicle probes, are becoming increasingly important due to their low cost and the vast amounts of traffic data produced. However, traffic data from ITS sources raise new concerns about data quality. The quality of probe data in South Africa and other developing countries is unknown. This study sets out to investigate the quality of TomTom historical average speeds on selected freeway segments in South Africa. The study compared TomTom historical speed estimates and reference speeds on six directional segments on the N1 and R21 freeways. The reference data used was Automatic Number Plate Recognition (ANPR) data, a component of Open Road Tolling (ORT) in Gauteng. A freeway segment is the road section between two toll gantries. All 15-minute and 1-hour intervals between 05:00 and 20:00 during the weekdays (Monday – Friday) in February 2015 were grouped and aggregated. The quality measures evaluated were accuracy, completeness, validity, coverage and accessibility. To evaluate accuracy, three error quantities were determined, namely signed error, average absolute speed error (AASE) and speed error bias (SEB). The allowable errors for the signed error, AASE and SEB were ±10 %, 10 km/h and ±7.5 km/h, respectively. TomTom speeds were highly consistent with the reference speeds. The error quantities for the combined freeway segments were less than the allowable errors. The signed errors and AASE for all the six individual freeway segments were also less than the allowable errors. In five of the six sections, the SEB was less than the allowable error. There were no significant differences between the error quantities derived from 15-minute and 1-hour interval speeds for the combined and individual freeway segments. On the other hand, validity was dependent on the selected measure. TomTom speeds were of very high quality based on the signed error and AASE, whereas the same data was of moderate quality based on the SEB. Although the TomTom speeds were within the specified accuracy thresholds, the speed estimates were generally lower than the reference speeds throughout the analysis period. TomTom estimates were better at low speeds and the quality of TomTom estimates declined with an increase in speed. It is possible that the low TomTom speed estimates were due to a sample that was not a true representation of the traffic stream. Importantly, it is possible to enhance the accuracy of TomTom speed estimates by using certain percentile speeds instead of average speeds.

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