No description available.

No description available.

No description available.

No description available.

Traffic congestion is increasingly becoming a severe problem in many large cities around the world. The problem is more complex in developing countries where cities are growing at a much faster rate than those in the developed world. Advanced Traffic Management Systems (ATMS) are one of the Intelligent Transport Systems (ITS) technologies that have been recommended and used as a tool to ease congestion problems in many large cities in the developing world. However, it is unknown how specific local conditions commonly observed in these cities, such as poor lane discipline and complex road user interactions, affect the performance of these systems. GETRAM (Generic Environment for Traffic Analysis and Modeling) was used in this research as a tool to develop microscopic traffic simulation models for the city of Bandung in Indonesia. The field data in this research, comprising throughputs, queue lengths and travel times, were collected during peak and off peak periods from all 90 signalised intersections connected to SCATS (Sydney Co-ordinated Adaptive Traffic System). This field data is believed to comprise one of the largest sets of “real world” data available for the development and validation of microscopic traffic simulation models. Two data sets were collected for this research: the first was used to develop and calibrate the simulation model and the second was used for validation. A number of statistical tests were used to determine the adequacy of the model in replicating traffic conditions. The results of statistical tests clearly showed that all of the calibrated and validated models reproduced field conditions with an acceptable degree of confidence. Therefore, the models were accepted as accurate and valid replications of the “real world”. The validated models were then used to evaluate the performance of SCATS which was implemented in Bandung in June 1997 as a pilot project. The results of comparative evaluation of the models under SCATS and under the Fixed Time control (without SCATS) demonstrated that SCATS did not necessarily always produce better results than the Fixed Time control. Furthermore, the performance of SCATS was strongly influenced by specific local conditions in the city. The multiple regression method was used to investigate the relationship between the traffic performance measures and significant basic variables. Based on this analysis, the main findings were: first, throughput was found to increase at intersections with higher v/c (volume to capacity) ratios. Second, throughput was found to decrease at intersections with higher numbers of phases and movements, longer widths of leg intersections, and farther distances to adjacent intersections. Third, queue length was found to increase at intersections with higher numbers of phases and movements. Based on the above findings, a number of improvements were recommended to enhance the performance of SCATS. This research also used traffic simulation to evaluate the impacts of these recommended improvements in increasing the performance of SCATS. The main findings from this evaluation were: first, restricted number of phases and movements at selected intersections substantially increased the traffic flow (78%) and decreased the queue length (by 55 to 67%) at the intersection. Second, making leg intersections wider—without physically building additional road capacity but by changing the stream with higher road hierarchy and higher v/c ratio from a two-way road into a one-way road—has a great impact on enhancing the performance of SCATS. Traffic flows were found to increase between 7 and 106%, and queue lengths were found to markedly decrease between 77 and 100% at all the suggested intersections. Third, the application of SCATS at intersections which are not closely spaced was not effective. Therefore, it is recommended that intersections which are not closely spaced remain under the Fixed Time control. The results and findings from this study provide road authorities in developing countries with an appreciation and enhanced understanding of the factors that influence the performance of traffic management systems in cities with similar characteristics to those in Bandung. These findings will also assist traffic engineers determine the best practices for the implementation of advanced traffic control systems in their cities.

No description available.

No description available.

Traffic congestion is increasingly becoming a severe problem in many large cities around the world. The problem is more complex in developing countries where cities are growing at a much faster rate than those in the developed world. Advanced Traffic Management Systems (ATMS) are one of the Intelligent Transport Systems (ITS) technologies that have been recommended and used as a tool to ease congestion problems in many large cities in the developing world. However, it is unknown how specific local conditions commonly observed in these cities, such as poor lane discipline and complex road user interactions, affect the performance of these systems. GETRAM (Generic Environment for Traffic Analysis and Modeling) was used in this research as a tool to develop microscopic traffic simulation models for the city of Bandung in Indonesia. The field data in this research, comprising throughputs, queue lengths and travel times, were collected during peak and off peak periods from all 90 signalised intersections connected to SCATS (Sydney Co-ordinated Adaptive Traffic System). This field data is believed to comprise one of the largest sets of “real world” data available for the development and validation of microscopic traffic simulation models. Two data sets were collected for this research: the first was used to develop and calibrate the simulation model and the second was used for validation. A number of statistical tests were used to determine the adequacy of the model in replicating traffic conditions. The results of statistical tests clearly showed that all of the calibrated and validated models reproduced field conditions with an acceptable degree of confidence. Therefore, the models were accepted as accurate and valid replications of the “real world”. The validated models were then used to evaluate the performance of SCATS which was implemented in Bandung in June 1997 as a pilot project. The results of comparative evaluation of the models under SCATS and under the Fixed Time control (without SCATS) demonstrated that SCATS did not necessarily always produce better results than the Fixed Time control. Furthermore, the performance of SCATS was strongly influenced by specific local conditions in the city. The multiple regression method was used to investigate the relationship between the traffic performance measures and significant basic variables. Based on this analysis, the main findings were: first, throughput was found to increase at intersections with higher v/c (volume to capacity) ratios. Second, throughput was found to decrease at intersections with higher numbers of phases and movements, longer widths of leg intersections, and farther distances to adjacent intersections. Third, queue length was found to increase at intersections with higher numbers of phases and movements. Based on the above findings, a number of improvements were recommended to enhance the performance of SCATS. This research also used traffic simulation to evaluate the impacts of these recommended improvements in increasing the performance of SCATS. The main findings from this evaluation were: first, restricted number of phases and movements at selected intersections substantially increased the traffic flow (78%) and decreased the queue length (by 55 to 67%) at the intersection. Second, making leg intersections wider—without physically building additional road capacity but by changing the stream with higher road hierarchy and higher v/c ratio from a two-way road into a one-way road—has a great impact on enhancing the performance of SCATS. Traffic flows were found to increase between 7 and 106%, and queue lengths were found to markedly decrease between 77 and 100% at all the suggested intersections. Third, the application of SCATS at intersections which are not closely spaced was not effective. Therefore, it is recommended that intersections which are not closely spaced remain under the Fixed Time control. The results and findings from this study provide road authorities in developing countries with an appreciation and enhanced understanding of the factors that influence the performance of traffic management systems in cities with similar characteristics to those in Bandung. These findings will also assist traffic engineers determine the best practices for the implementation of advanced traffic control systems in their cities.

Traffic signs are ubiquitous in the road environment, and are a crucial and cost-effective means of ensuring traffic safety. In Queensland, Australia, a class of temporary traffic signs is used for roadwork applications, and has recently been expanded to include Multiple-Message Signs: a novel, and as yet empirically untested system, which presents numerous advantages in terms of flexibility and economy. However, potential Human Factors problems surround aspects of the design of multiple message signs. In particular, the efficiency with which information is communication may be compromised relative to single message signs. The project involved a series of laboratory studies focussing on the behavioural requirements of temporary roadworks signs, beginning with the improvement of response characteristics of a sign used to communicate lane-closure. In the first empirical study, a proposed redesign of the Lane-Status sign based on principles of warning communication was found to be more effective than the original sign. The same sign was then examined in the context of multiple-message presentation, and significant cost s with respect to the speed and accuracy of responses relative to single-message presentation were found. A subsequent study investigated multiple-message presentation of speed limit information, which is more familiar and widely encountered than lane-closure information. Similar costs for multiple-message presentation were found. However, there were data to suggest that the additional information in multiple-message signs, if used correctly, may offer drivers and additional incentive to reduce speed. The next two studies were concerned with the effects of presentation, content type (e.g., speed-limit, symbolic and text-based) and visual clutter on recognition and visual search for traffic signs. The presentation of information via multiple message signs was compared with spatially distributed single message signs, with information matched with respect to message length and sign content. Overall advantages for multiple message presentation were found for recognition, which were particularly robust for speed limit information. The results for visual search indicated some benefits to multiple message presentation, but were less decisive than those for recognition. The final two studies investigated the possibility of improving response characteristics of single-message signs with sequential, rather then individual presentation. The role of the temporal interval between successive sign presentations was explored, which has implications for the feasibility of sequential presentation in practice. In addition, the nature of sign pairs presented in sequence – identical, or of the same meaning – was found to be important. Generally, benefits to sequential presentation diminished with increases in the temporal separation interval. In terms of practical implications, the viability of introducing the proposed design changes to the Lane Status sign is discussed. The results pertaining to multiple-message sign are evaluated in the context of published design guidelines, and theoretical and practical issues surrounding sequential sign presentation are reviewed. Finally, possibilities for future research, in part based on the limitations of the current work, are expounded.

Traffic signs are ubiquitous in the road environment, and are a crucial and cost-effective means of ensuring traffic safety. In Queensland, Australia, a class of temporary traffic signs is used for roadwork applications, and has recently been expanded to include Multiple-Message Signs: a novel, and as yet empirically untested system, which presents numerous advantages in terms of flexibility and economy. However, potential Human Factors problems surround aspects of the design of multiple message signs. In particular, the efficiency with which information is communication may be compromised relative to single message signs. The project involved a series of laboratory studies focussing on the behavioural requirements of temporary roadworks signs, beginning with the improvement of response characteristics of a sign used to communicate lane-closure. In the first empirical study, a proposed redesign of the Lane-Status sign based on principles of warning communication was found to be more effective than the original sign. The same sign was then examined in the context of multiple-message presentation, and significant cost s with respect to the speed and accuracy of responses relative to single-message presentation were found. A subsequent study investigated multiple-message presentation of speed limit information, which is more familiar and widely encountered than lane-closure information. Similar costs for multiple-message presentation were found. However, there were data to suggest that the additional information in multiple-message signs, if used correctly, may offer drivers and additional incentive to reduce speed. The next two studies were concerned with the effects of presentation, content type (e.g., speed-limit, symbolic and text-based) and visual clutter on recognition and visual search for traffic signs. The presentation of information via multiple message signs was compared with spatially distributed single message signs, with information matched with respect to message length and sign content. Overall advantages for multiple message presentation were found for recognition, which were particularly robust for speed limit information. The results for visual search indicated some benefits to multiple message presentation, but were less decisive than those for recognition. The final two studies investigated the possibility of improving response characteristics of single-message signs with sequential, rather then individual presentation. The role of the temporal interval between successive sign presentations was explored, which has implications for the feasibility of sequential presentation in practice. In addition, the nature of sign pairs presented in sequence – identical, or of the same meaning – was found to be important. Generally, benefits to sequential presentation diminished with increases in the temporal separation interval. In terms of practical implications, the viability of introducing the proposed design changes to the Lane Status sign is discussed. The results pertaining to multiple-message sign are evaluated in the context of published design guidelines, and theoretical and practical issues surrounding sequential sign presentation are reviewed. Finally, possibilities for future research, in part based on the limitations of the current work, are expounded.