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Analysis of single-lane approaches at signalized intersections
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Book
this mode versus other modes of transportation can be highlighted in its minimal land use, minimal air and noise pollution, energy efficiency and conservation, safety, effective resource utilization, and moderate cost of service. This research was undertaken with the intent of developing more reliable methods for characterization, evaluation and prediction of rail transport activity and performance characteristics at the global level. Data to support this study were extracted from centralized sources such as the United Nations and the data banks of other national and international agencies. Various statistical methods such as descriptive analysis, correlation analysis, principal component analysis, cluster analysis, and regression analysis were utilized for processing and statistical investigation of a broad set of rail transport data as well as market and environmental data for nations with railroad systems. A representative set of rail transport performance measures was developed to satisfy the need for a comprehensive and objective characterization of railroad systems. These measures were examined in relation to the economic, geographic, demographic, other-transport-modes, and political attributes of nations. It was hypothesized that these nonrail attributes were most indicative of the potential market for rail transportation. The nations were groups on the basis of their 1980 performance characteristics. That distribution provides an insight into the existing status of world rail systems. Homogeneous groups of nations with similar market potential for rail transportation were developed. As a result, individual as well as comparative performance evaluations of peer group nations should produce unbiased and reasonable conclusions. Aggregate and disaggregate prediction models were developed based on stepwise multiple regression analysis. While the aggregate models estimate potential achievable performance on the global level, the disaggregate models provide estimations of the possible achievable rail transport target levels of performance for every group of nations.
Reviews consuming process of manual image evaluation are considered to be too high. To overcome these problems and to enable the use of all advantages of aerial observation, a method for automatic image evaluation was designed. This study presents methods for automatic calculation, representation, and analysis of all significant traffic parameters. In the study, the advantages and disadvantages of this type of observation are investigated. A specially developed system of transfer equations allows comparisons and combinations of local, instantaneous, “moving,” and time-space observations. Observations from a flying aircraft are shown to be a special and, in certain aspects expanded, form of the wellknown “Moving Observer.” In order to calculate unbiased traffic parameters, three distinct groups of parameters are defined. For each group, an algorithm is given to calculate its parameters. Thus, it is possible to practically calculate the most important traffic parameters. Using a program to estimate the time-space trajectory for all vehicles observed more than once, traffic conditions in areas not directly observed from the aircraft can be described. As a result, a data set becomes available that describes traffic behaviour of all vehicles in the most general form. Three-dimensional representation and further statistical evaluation of this traffic data offer a wide range of different applications. For instance, analysis of variance can be used to determine type and size of underlying influences on traffic parameters (both time-dependent and/or distance-dependent). Other methods can be used as appropriate. The results of several applications of the method confirm that unbiased, representative, and reliable traffic parameters can be calculated automatically from aerial (“moving”) observations. Thus, the advantages of this type of observation can be used to its full extent in practice.
Analysis of single-lane approaches at signalized intersections. Papayannoulis, Vassilios Nicolaos, Ph.D. Polytechnic University, 1989. 124 pp. Advisor: Roger P. Roess Order Number DA8922678
TRAFFIC ANALYSIS
Aerial observation of road traffic: Properties, calculation and application of traffic parameters. Becker, Udo J., Dr. Ing. Kurlsruhe University (West Germany), 1989. 166 pp. Supervisors: W. Leutzbach and H. P. Bahr. (In German; not available from University Microfilms, Inc.).
In certain applications, aerial observation of road traffic is advantageous compared to all other types of traffic observation. However, this technique is rarely used in practice as costs of the difficult and time-
During the planning process of new street developments, traffic engineers are sometimes required to trade off an increase in the predicted level-of-service (LOS) for a less expensive design. The decision is based on the ability of the existing methodologies to predict capacities and anticipated delays for the various street configurations. Therefore, it is critical to employ models that account for all the pertinent parameters. Research for capacity of left-turn lanes with permissive phasing has primarily focused on exclusive lanes, with very few references on the operation of a shared lane and practically none for a single-lane approach.
Book Reviews This research effort is focused on the analysis of the unique characteristics of single-lane operations at signalized intersections, the development of a leftturn equivalent model which provides the basis for a capacity analysis methodology. The analysis is founded on the concept of the queue clearance time and the principle that single-lane approaches should not be viewed individually but rather in tandem with the opposing approach. The parameters utilized in the predictive equations were based on information provided from individual cycles rather than 15minute periods. The proposed general procedure is a three-step process. The first step involves the calculation of the ideal queue clearance time from an exponential model, while the second step involves the introduction of the adjustment factors incorporated in the 1985 Highway Capacity Manual (HCM) for estimating prevailing queue clearance time. The third step involves the calculation of the left-turn equivalent, based on variables reflecting the relative friction of the subject approach. The predictive equations proved to be useful not only for a microscopic analysis, but for a macroscopic one as well. Furthermore, the methodology can be applied in both operational and design capacity analysis.
Analysis of traffic spatial shift resulting from optimal signal timing and special generators. Dikun, Suyono, Ph.D. The University of Wisconsin-Mu&son, 1988. 241 pp. Supervisor: Robert L. Smith, Jr. Order Number DA8903274 Traffic spatial shift as a result of traffic signal optimization in an urban corridor was investigated based on both the existing condition and potential future conditions with higher travel demand. The impacts of this spatial shift on the optimal signal timing, and vice versa, was analyzed through an iterative application of a traffic signal optimization model and a traffic diversion model. TRANSYT7F was used to optimize the signal system in the corridor network and to estimate overall traffic performance, including route travel times. A simple traffic diversion model developed from a logit choice model was chosen to represent the aggregate response of travelers to the choice situation. An algorithm for the interaction of TRANSYT7F and the diversion model was developed so that traffic equilibrium can be reached quickly. The initial optimization of signal timing created differences in travel time on alternative routes of 5 %6%. The iterative application of the traffic diversion model followed by simulation of the new flow conditions with TRANSYT-7F resulted in changes in link flow levels of l %-3 %. The new traffic flow conditions at equilibrium, however, did not significantly
45
affect the overall network measures of effectiveness (MOEs). Subsequent reoptimization of the signal timing based on the new link flow levels followed by traffic diversion to reach equilibrium resulted in only a 1% reduction in the performance index (PI) after the third optimization. Incremental expansion of the base outbound flows by 10X-30% was used to model the potential impacts of special generators on signal timing and spatial shift. In contrast to the base flow simulation, the performance of the network with the higher flows declined (higher PI) by 2%-8% in reaching equilibrium. Subsequent reoptimization resulted in improvements in the PI at equilibrium of up to 5 % . For the highly limited range of network, traffic signal, and flow conditions examined in this research, a reoptimization may be warranted if the travel time differences exceed 15 % in both directions.
Computerization of heuristic-based decisionmaking problems in transportation engineering. Faghri, Ardeshir, Ph.D. University of Virginia, 1989. 292 pp. Order Number DA9002842 This study investigates the potential applications of knowledge-based expert systems in transportation engineering. The three major topics covered are: (i) A description of the fundamental concepts of knowledge-based expert systems and how they relate to transportation engineering. The general differences between expert systems and conventional computer programs are summarized, and the process of transferring knowledge from human experts to computers is described. The architecture of knowledge-based expert systems is shown to separate the knowledge of the problem domain (knowledge base) from general problem solving (inference engine). Different approaches to each of these tasks are described and recent applications to several transportation engineering problems are presented. (ii) The selection of appropriate representation techniques for different classes of transportation engineering problems. Three of the most commonly used techniques for representing knowledge in the knowledge base of knowledge-based expert systems are described; and the highlights, shortcomings, and applications of each technique are explained. This section focuses on an examination of the significance of the means of representing the knowledge base in the development of knowledge-based expert systems, with special reference to five classes of transportation engineering problems-planning, operations and control, design, construction and maintenance, and management and finance. Under each class, one or two transportation and traffic problems suitable for knowledge-based expert systems development are briefly described, and the most suitable representation technique(s) for their development is recommended. (iii) A descrip-
Book
this mode versus other modes of transportation can be highlighted in its minimal land use, minimal air and noise pollution, energy efficiency and conservation, safety, effective resource utilization, and moderate cost of service. This research was undertaken with the intent of developing more reliable methods for characterization, evaluation and prediction of rail transport activity and performance characteristics at the global level. Data to support this study were extracted from centralized sources such as the United Nations and the data banks of other national and international agencies. Various statistical methods such as descriptive analysis, correlation analysis, principal component analysis, cluster analysis, and regression analysis were utilized for processing and statistical investigation of a broad set of rail transport data as well as market and environmental data for nations with railroad systems. A representative set of rail transport performance measures was developed to satisfy the need for a comprehensive and objective characterization of railroad systems. These measures were examined in relation to the economic, geographic, demographic, other-transport-modes, and political attributes of nations. It was hypothesized that these nonrail attributes were most indicative of the potential market for rail transportation. The nations were groups on the basis of their 1980 performance characteristics. That distribution provides an insight into the existing status of world rail systems. Homogeneous groups of nations with similar market potential for rail transportation were developed. As a result, individual as well as comparative performance evaluations of peer group nations should produce unbiased and reasonable conclusions. Aggregate and disaggregate prediction models were developed based on stepwise multiple regression analysis. While the aggregate models estimate potential achievable performance on the global level, the disaggregate models provide estimations of the possible achievable rail transport target levels of performance for every group of nations.
Reviews consuming process of manual image evaluation are considered to be too high. To overcome these problems and to enable the use of all advantages of aerial observation, a method for automatic image evaluation was designed. This study presents methods for automatic calculation, representation, and analysis of all significant traffic parameters. In the study, the advantages and disadvantages of this type of observation are investigated. A specially developed system of transfer equations allows comparisons and combinations of local, instantaneous, “moving,” and time-space observations. Observations from a flying aircraft are shown to be a special and, in certain aspects expanded, form of the wellknown “Moving Observer.” In order to calculate unbiased traffic parameters, three distinct groups of parameters are defined. For each group, an algorithm is given to calculate its parameters. Thus, it is possible to practically calculate the most important traffic parameters. Using a program to estimate the time-space trajectory for all vehicles observed more than once, traffic conditions in areas not directly observed from the aircraft can be described. As a result, a data set becomes available that describes traffic behaviour of all vehicles in the most general form. Three-dimensional representation and further statistical evaluation of this traffic data offer a wide range of different applications. For instance, analysis of variance can be used to determine type and size of underlying influences on traffic parameters (both time-dependent and/or distance-dependent). Other methods can be used as appropriate. The results of several applications of the method confirm that unbiased, representative, and reliable traffic parameters can be calculated automatically from aerial (“moving”) observations. Thus, the advantages of this type of observation can be used to its full extent in practice.
Analysis of single-lane approaches at signalized intersections. Papayannoulis, Vassilios Nicolaos, Ph.D. Polytechnic University, 1989. 124 pp. Advisor: Roger P. Roess Order Number DA8922678
TRAFFIC ANALYSIS
Aerial observation of road traffic: Properties, calculation and application of traffic parameters. Becker, Udo J., Dr. Ing. Kurlsruhe University (West Germany), 1989. 166 pp. Supervisors: W. Leutzbach and H. P. Bahr. (In German; not available from University Microfilms, Inc.).
In certain applications, aerial observation of road traffic is advantageous compared to all other types of traffic observation. However, this technique is rarely used in practice as costs of the difficult and time-
During the planning process of new street developments, traffic engineers are sometimes required to trade off an increase in the predicted level-of-service (LOS) for a less expensive design. The decision is based on the ability of the existing methodologies to predict capacities and anticipated delays for the various street configurations. Therefore, it is critical to employ models that account for all the pertinent parameters. Research for capacity of left-turn lanes with permissive phasing has primarily focused on exclusive lanes, with very few references on the operation of a shared lane and practically none for a single-lane approach.
Book Reviews This research effort is focused on the analysis of the unique characteristics of single-lane operations at signalized intersections, the development of a leftturn equivalent model which provides the basis for a capacity analysis methodology. The analysis is founded on the concept of the queue clearance time and the principle that single-lane approaches should not be viewed individually but rather in tandem with the opposing approach. The parameters utilized in the predictive equations were based on information provided from individual cycles rather than 15minute periods. The proposed general procedure is a three-step process. The first step involves the calculation of the ideal queue clearance time from an exponential model, while the second step involves the introduction of the adjustment factors incorporated in the 1985 Highway Capacity Manual (HCM) for estimating prevailing queue clearance time. The third step involves the calculation of the left-turn equivalent, based on variables reflecting the relative friction of the subject approach. The predictive equations proved to be useful not only for a microscopic analysis, but for a macroscopic one as well. Furthermore, the methodology can be applied in both operational and design capacity analysis.
Analysis of traffic spatial shift resulting from optimal signal timing and special generators. Dikun, Suyono, Ph.D. The University of Wisconsin-Mu&son, 1988. 241 pp. Supervisor: Robert L. Smith, Jr. Order Number DA8903274 Traffic spatial shift as a result of traffic signal optimization in an urban corridor was investigated based on both the existing condition and potential future conditions with higher travel demand. The impacts of this spatial shift on the optimal signal timing, and vice versa, was analyzed through an iterative application of a traffic signal optimization model and a traffic diversion model. TRANSYT7F was used to optimize the signal system in the corridor network and to estimate overall traffic performance, including route travel times. A simple traffic diversion model developed from a logit choice model was chosen to represent the aggregate response of travelers to the choice situation. An algorithm for the interaction of TRANSYT7F and the diversion model was developed so that traffic equilibrium can be reached quickly. The initial optimization of signal timing created differences in travel time on alternative routes of 5 %6%. The iterative application of the traffic diversion model followed by simulation of the new flow conditions with TRANSYT-7F resulted in changes in link flow levels of l %-3 %. The new traffic flow conditions at equilibrium, however, did not significantly
45
affect the overall network measures of effectiveness (MOEs). Subsequent reoptimization of the signal timing based on the new link flow levels followed by traffic diversion to reach equilibrium resulted in only a 1% reduction in the performance index (PI) after the third optimization. Incremental expansion of the base outbound flows by 10X-30% was used to model the potential impacts of special generators on signal timing and spatial shift. In contrast to the base flow simulation, the performance of the network with the higher flows declined (higher PI) by 2%-8% in reaching equilibrium. Subsequent reoptimization resulted in improvements in the PI at equilibrium of up to 5 % . For the highly limited range of network, traffic signal, and flow conditions examined in this research, a reoptimization may be warranted if the travel time differences exceed 15 % in both directions.
Computerization of heuristic-based decisionmaking problems in transportation engineering. Faghri, Ardeshir, Ph.D. University of Virginia, 1989. 292 pp. Order Number DA9002842 This study investigates the potential applications of knowledge-based expert systems in transportation engineering. The three major topics covered are: (i) A description of the fundamental concepts of knowledge-based expert systems and how they relate to transportation engineering. The general differences between expert systems and conventional computer programs are summarized, and the process of transferring knowledge from human experts to computers is described. The architecture of knowledge-based expert systems is shown to separate the knowledge of the problem domain (knowledge base) from general problem solving (inference engine). Different approaches to each of these tasks are described and recent applications to several transportation engineering problems are presented. (ii) The selection of appropriate representation techniques for different classes of transportation engineering problems. Three of the most commonly used techniques for representing knowledge in the knowledge base of knowledge-based expert systems are described; and the highlights, shortcomings, and applications of each technique are explained. This section focuses on an examination of the significance of the means of representing the knowledge base in the development of knowledge-based expert systems, with special reference to five classes of transportation engineering problems-planning, operations and control, design, construction and maintenance, and management and finance. Under each class, one or two transportation and traffic problems suitable for knowledge-based expert systems development are briefly described, and the most suitable representation technique(s) for their development is recommended. (iii) A descrip-