Browsing by browse.metadata.cluster "Built Environment"

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    Development of a new asphalt mix design manual for South Africa
    (2015-08) Anochie-Boateng, J; O’Connell, JS; Verhaeghe, BMJ; Myburgh, P
    A need existed to update the South African design methods for asphalt mixes, particularly in the light of current developments in the country such as the revision of the South African Road Design System (SARDS), and the increasing demand for, and the use of products such as high modulus asphalt mixes with reclaimed asphalt and slags, warm mix, and cold mix as alternative mixes to conventional hot-mix asphalt. Generally, there is a worldwide shift from empirical-based asphalt mix design approach towards performance-related design approaches, due to advances in asphalt technology, increased volumes of heavy vehicles on roads, and there is also a demand for higher performance mixes, and a need to review the current criteria for asphalt layers in contract specifications. This paper presents the development of a new asphalt design manual. The paper presents key highlights such as (a) the performance grade binder selection methodology in which the binder is selected based on loading and environmental conditions, as a replacement of the traditional penetration grade binder selection method, (b) the move from aggregate grading bands (as per the current South African Committee of Transport Officials specifications) towards the use of control points to select the design aggregate grading, and (c) the three levels of asphalt mix designs proposed for the manual. The manual however, requires validation through additional laboratory testing before it can be used with confidence by industry.
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    The influence of ballast fouling on track settlement
    (2018-07) Rampersad, Ashiel; George, Theresa B; Mokoena, Refiloe; Mgangira, Martin B; Gräbe, PJ
    The contamination of railway ballast (referred to as ballast fouling) is commonly caused by ballast particle degradation, external debris fouling due to surface spillage and clay fouling due to subgrade pumping. Intrusion of these fines in the ballast layer can impede rapid drainage which is necessary for good track performance. There is little research relating both fouled ballast and track settlement in a South African context. This paper discusses the effect of coal contaminated ballast on track settlement by use of a large scale “box test” apparatus. A series of tests was conducted on ballast aggregate, typically used on heavy haul railway lines in South Africa, with varying percentages of coal dust material (0, 8.4, 16.9, 25.3 and 33.8 % by weight of aggregate). Testing was conducted at 10 Hz for 100 000 cycles with a moisture content of 5.0 %. Results indicated an increase in settlement of between 11.7 and 40.2 % per 10 % increase in coal dust contamination. It is envisaged that this research will aid the South African railway industry in identifying the critical levels of coal fouling which will hence contribute towards reducing maintenance costs as well as improving railway safety and network reliability.
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    Is open source GIS feasible in military operations? Evaluation by applying a USE case
    (Faculty of Military Science (Military Academy) University of Stellenbosch, 2020-02) Henrico, S; Coetzee, S; Cooper, Antony K
    The study of terrain and all its related elements and facets are of crucial importance to the military. Lodi, Smit, and Ayirebi agreed with this statement and added that the importance of terrain was recognised by military leaders more than two thousand years ago. Military operations can occur at any of the three levels of war: tactical, operational and strategic and can be a combat operation or a military operation other than war (MOOTW). Information about the geography empowers a military commander to plan and execute a mission successfully. As technology developed and evolved, geographic information systems (GIS) have come to play a major role in this. Today, a military operation without the use of GIS is unthinkable. In a developing country like the South Africa, however, licenses for proprietary GIS software, vendor-exclusive training and the bureaucracy of the procurement cycle add to the time and costs of a mission. The question arises whether open source software is a feasible alternative. Since the South African National Defence Force was initially trained in the use of proprietary software and it therefore became a strong habit, the perception now exits that FOSSGIS products are neither mature enough nor user-friendly enough to be used in military operations. This study evaluates the use of an open source desktop GIS product, QGIS, in a use case for a military operation “other than war” (MOOTW). QGIS outputs were compared to those produced in ArcGIS, a proprietary desktop GIS product widely used in military operations. The user-friendliness of the two products as well as pricing was also compared. Results show that the QGIS outputs provide the operational commander with equivalent information to successfully plan and execute a mission. This implies that open source GIS is suitable for military operations, especially those with limited budgets and at short notice, such as in the case of disaster relief.