M.Ing. (Transportation) / Consecutive green phases at signalized intersections are separated by an amber and sometimes all-red period to allow a safe changeover from flow in one direction to another. Al though this signal change interval consists of only a few seconds, existing practice in setting this signal change interval varies considerably. Research on this subj ect has focused on understanding how individual drivers react when they are confronted by a change signal. Identifying the factors that describe the need for different change intervals can most easily be determined by measuring the aggregated behaviour of motorists under conditions where these factors vary. Evidence suggests that the South African driver overseas counterpart regarding his attitude towards interval differs from his the signal change Field observations of drivers' aggregated behaviour when confronted by a change interval were made at 17 approaches to 9 different intersections. The linear relationship between the signal change interval and various factors which apparently have an influence on the need for such a period were determined. The regression models were also structured to allow evaluation of existing models such as the well-known ITE-formula. The results were evaluated statistically. It was not possible to calibrate the ITE-formula for South African conditions. The approach adopted here conforms to tiling designs that use a constant (for a specific approach) amber interval. This constant is probably a summation of the influence of all the factors which influence the need for a signal change interval. The use of the clearance time for a crossing, as the all-red period, is also ascertained.

Road safety is an aspect of major concern on road networks, not only on a local scale in South Africa, but also on a global scale. South Africa is experiencing an unacceptably high rate of fatal road traffic crashes and as a result has one of the highest per capita rate of road fatalities in the world. The Global Plan for the Decade of Action for Road Safety 2011 – 2020 was published in 2011 by the World Health Organisation (WHO) to guide and assist countries with the improvement of road safety. The management of vehicle speeds is one of numerous important interventions identified in the Global Plan. The technical and economic feasibility of using a specific Road safety is an aspect of major concern on road networks, not only on a local scale in South Africa, but also on a global scale. South Africa is experiencing an unacceptably high rate of fatal road traffic crashes and as a result has one of the highest per capita rate of road fatalities in the world. The Global Plan for the Decade of Action for Road Safety 2011 – 2020 was published in 2011 by the World Health Organisation (WHO) to guide and assist countries with the improvement of road safety. The management of vehicle speeds is one of numerous important interventions identified in the Global Plan. The technical and economic feasibility of using a specific technology, namely Vehicle Activated Signs (VAS), to contribute to the overall improvement of road safety on a national level in South Africa were investigated, with particular emphasis on the improvement of road safety through the reduction of fatal road traffic crashes. VAS are part of a range of measures that can be used to curb vehicle speeds, similar to conventional measures like speed cameras and traffic calming devices. VAS technology has seen limited use in South extrapolation of results from SCC’s VAS effectiveness study, and the application of these results to the South African road safety and road user statistics for the one year period March 2011 to March 2012. Key factors relating to speed and general driver obedience were also taken into consideration. It was established that the use of VAS would lead to a moderate reduction in the number of fatal road traffic crashes that occur annually, which in turn holds financial and socio-economic benefits for South Africa. A comparison of selected products available from two South African based electronic road sign manufacturing companies with conventional VAS was also carried out, focussing on product function, use and cost. It has been concluded that it would be technically and economically feasible to introduce VAS on the South African road network to improve the prevailing road safety situation.

M.Ing. / Another method is suggested in this paper to decide on the method of control at intersections. A computer program has been developed to simulate traffic on a macroscopic basis to obtain cost for delay, fuel consumption, accidents, maintenance, oil consumption and capital investment. The total cost per vehicle proved that the existing criteria are conservative in so far they warrant traffic signs earlier than necessary ...

This study documents and analyses the first established record of taxi hand signs and their respective destinations in South Africa. It demonstrates how taxi hand signification developed into a useful language over time, out of a desperate need for transport amongst black, multi-cultural and multi-lingual people living in South Africa. Its central objective is to recognise taxi hand signs as metaphors for processes of history in pre- and post-apartheid South Africa. This is a study that crosses disciplinary boundaries and marries fine art, anthropology and philosophy in exploring new meanings and understandings of taxi hand signs. In this way, it demonstrates the extent to which art informs other disciplines in extraordinary ways, adding to the value of inter-disciplinary research. The research indicates that taxi signs are part of an evolving, well-functioning, gestural language for sighted commuters. It goes further to probe the question of how blind commuters might have access to the signs, thereby enhancing their independence and movement. The study responds to this question through the design of a new, tactile shape-language of taxi hand signs for blind people. Qualitative research techniques were employed throughout the three phases of the research, namely: preliminary research, research design, and social and fine art responses. The methodologies utilised in the phases were sampling, semistructured interviews and participant observation. These were each employed at specific times to meet specific needs of different phases. I, along with some coresearchers, applied these in taxi ranks, taxi associations and on the streets of Gauteng. The methods used attest to the fact that when new knowledge was sought with key informants in the taxi industry, the different methodologies could be used to verify and corroborate the informants’ information, which in turn become the keystones of knowledge distribution in the thesis. With limited documentation on the emergence of taxi hand signs in the industry, the informants furnished unexplored background information, which I have interpreted in my artworks, films, books, stamps, maps and the blind shape-language. 16 The anthropological research also probed the function of signification through literary criticism. This involved an investigation of the components of the process of signification into its constituent parts in order to conceptualise and contextualise taxi hand signing and its particular relations and narrative content within the greater field of gestural signification. The response of art and artists to anthropological, historical and current approaches was also explored, again to provide context to my art that evolved out of the research. These involved conceptual and graphic art interpretations probing movement, time, space and signification, which led to an art exhibition at the Wits Art Museum (henceforth referred to as WAM) from 12 June to 14 July 2013. Taxi hand signs are continually evolving as new destinations and narratives arise. Together with the art responses document, this thesis records and promotes the established body of the current taxi hand signs, destinations and narratives, for both sighted and blind people, by providing written, visual and sensory evidence of a cultural phenomenon that was previously uncharted.

This thesis presents the results of an investigation into traffic operations and driver behaviour at traffic circles under South African conditions. The scarcity of local traffic circles necessitated the development of a simulation program (TRACSIM) to assist in the research process. This microscopic program for single lane circles is based on event updates and was calibrated and validated based on local data. Because the acceptance of gaps is such a vital part of the operation of a traffic circle, it was examined in detail. Specific attention was given to the possible use of a gap acceptance model based on variables other than time. Since the gap acceptance process also depends on the gap distribution in the circulating stream, the effect of the origin-destination pattern was also investigated. Two existing analysis techniques are evaluated and verified for local conditions, improving them where possible. Generally these techniques under-estimate traffic delay at local circles. Observations indicate a difference between the acceptance of gaps/lags in the entering and circulating stream of conflicting traffic as well as a difference between critical gaps and critical lags. The mean observed critical gaps/lags are larger than in other countries, which indicates that delays at local circles will be greater. Gap/lag acceptance based on critical distances rather than critical times was applied successfully in the simulation program TRACSIM. A method is proposed to estimate critical distances from the geometric layout of the circle. Critical gaps are not fixed, but should vary with at least the conflicting flows. The investigation of the effect of unbalanced flows on delay, showed that the variability in drivers' critical gaps is more a function of delay than of conflicting flow. Entry delays increase because of an increase in conflicting flows or because of an unfavourable imbalance of conflicting flows. In both instances the drivers' critical gaps will decrease. A variable critical gap model only based on conflicting flows will show no change in the drivers' critical gaps if the conflicting volumes remain constant, even though the actual average delay might increase because of an unfavourable imbalance in conflicting flows. / Thesis (Ph.D.)-University of Natal, Durban, 1997.