Showing papers on "Traffic simulation published in 1991"

A multi-band approach to arterial traffic signal optimization

Abstract: Progression schemes are widely used for traffic signal control in arterial streets. Under such a scheme a continuous green band of uniform width is provided in each direction along the artery at the desired speed of travel. A basic limitation of existing bandwidth-based programs is that they do not consider the actual traffic volumes and flow capacities on each link in their optimization criterion. Consequently they cannot guarantee the most suitable progression scheme for different traffic flow patterns. In this paper we present a new optimization approach for arterial progression that incorporates a systematic traffic-dependent criterion. The method generates a variable bandwidth progression in which each directional road section can obtain an individually weighted bandwidth (hence, the term multi-band). Mixed-integer linear programming is used for the optimization. Simulation results indicate that this method can produce considerable gains in performance when compared with traditional progression methods. It also lends itself to a natural extension for the optimization of grid networks.

Procedure for validation of microscopic traffic flow simulation models

Abstract: Model verification and validation are two important tasks in developing a traffic simulation model. Traffic simulation models have unique characteristics because of the interaction among the drivers, vehicles, and roadway. The effects of the interaction on traffic flow should be considered in verification and validation of the models. If these two tasks are not properly performed, a traffic simulation model may not provide accurate results. A procedure for verification and validation of microscopic traffic simulation models is developed, and its application to a car-following simulation model, CARSIM, is demonstrated. The validation part of the procedure is emphasized. The validation efforts are performed at the microscopic and macroscopic levels. For validation at the microscopic level, the speed change patterns and trajectory plots obtained from simulation models are compared with those from field data. For validation at the macroscopic level, the average speed, density, and volume for simulated platoons are compared with those of field data. Also, variation of these parameters when the platoons go through a disturbance and interrelationships between these variables computed from the simulation models and the field data are examined. Regression analysis and analysis of variance of the simulation results versus the field data are discussed. The procedure may be considered as a step toward development of a comprehensive systematic approach for verification and validation of traffic simulation models.

Laboratory assessment of driver route diversion in response to in-vehicle navigation and motorist information systems

Abstract: A laboratory investigation of driver use of in-vehicle navigation systems is described in this paper. This study is the first phase of a two part project in which the second phase will apply the driver behavior data to a traffic simulation model. The objective of the driver behavior experiment was to compare the effect of four navigation systems on driver diversion decisions when faced with traffic congestion. Three of the systems were developed on the basis of a heading-up map display. These systems varied from a basic map with vehicle position information to a highly complex map with position, congestion, and route guidance information. The fourth system consisted of simplified symbolic directions and distance to change information. The experiment simulated typical freeway trips using sequences of slides of real freeway scenes and auditory feedback controlled by a computer. Drivers were presented information on traffic congestion, vehicle speed and guide signs of off-ramps, and were motivated with monetary rewards and penalties to encourage diversion decisions that would minimize trip travel delays. In addition to several in-vehicle navigation system configurations, experimental variables included driver route familiarity, age group, and either commercial or noncommercial driving experience. The results showed that navigation system characteristics can have a significant effect on driver diversion behavior, with better systems allowing more anticipation of traffic congestion. This result was found over several different levels of congestion. Driver age also was a factor, with old drivers more reluctant to divert from the main freeway route. Route familiarity, commercial driving experience, and gender group variables were not significant factors in driver diversion decision making.

Dynamic network traffic assignment and route guidance via feedback regulation

Abstract: A deterministic, macroscopic modeling framework for dynamic traffic phenomena on networks consisting of freeways and urban streets is presented for nonelastic but time-varying traffic demands. A feedback methodology is applied to the network model to establish dynamic traffic assignment conditions. Specifically, a multivariable feedback regulator with integral parts and a simple bang-bang controller are developed and tested for a particular network traffic model. Because of three fundamental features (low computational effort, low sensitivity with respect to unknown demands and compliance rates, and integrated design procedure), the feedback concept appears attractive for a broad class of traffic control problems including route guidance systems.

A model for simulating traffic on two-lane rural roads; user guide and manual for TRARR version 3.2

Abstract: TRARR is a rural traffic simulation model developed at the Australian Road Research Board. The model can be used to investigate the effects on traffic operations of changes in either the road or traffic characteristics. TRARR has been used at ARRB on specific case studies requested by road authorities, and in general investigations of level of service and guidelines for rural road improvements. The model has also been provided to numerous organisations outside ARRB, many of them outside Australia. A new version, TRARR 3.2, has recently been released, with improved transportability and simplified user requirements. TRARR requires input data on the traffic stream, road characteristics, and what is to be observed and recorded. It then reviews the progress of each vehicle at frequent intervals as it moves along the simulated road. Decision rules for catching up, overtaking, merging and other aspects of behaviour are largely determined by the vehicle/driver characteristics supplied in one of the input files. Many of these parameters have been derived from other ARRB research projects. Outputs include travel time, journey speed, bunching, overtaking and fuel consumption information, as well as plots and terminal graphics displays (A).

Simulating the TravTek route guidance logic using the integration traffic model

Abstract: The first phase of the TravTek IVHS experiment will involve the use of in-vehicle Route Guidance Systems (RGS) to determine the best routes through the Greater Orlando Area. These routes will be computed in a distributive fashion based on minute-to-minute travel time updates that are provided by a central Traffic Management Center (TMC). This paper describes the most important traffic engineering aspects of the data fusion, dissemination, and in-vehicle processing of the TravTek system with the intent of demonstrating how the features of each of these steps can be modelled within the TravTek version of the INTEGRATION traffic simulation model. The simulation of these system features is initially intended to assist in developing appropriate TMC and in-vehicle unit system control settings, and to determine the sensitivity of the benefit estimates to alternate parameter settings or system configurations. The INTEGRATION simulation model will subsequently also be utilized to simulate and explore any level of market penetration traffic effects, as well as the transferability of the TravTek results to other networks and/or different demand patterns.

Freeway control using a dynamic traffic flow model and vehicle reidentification techniques

Abstract: Freeway traffic flow is described in terms of control theory. The detecting elements of millimeter-wave radar sensors, which detect speed and occupancy time by a 61-GHz continuous-wave doppler radar, are used. The regulating unit consists of variable traffic signs for traffic-dependent speed limit and alternative route guidance. The control unit consists of a local computer and a control center. The control strategy is based on a continuum theory of traffic flow, which takes into account characteristics of the speed distribution for different traffic states. For incident detection and early warning criteria, the model yields the traffic density as a crucial stability parameter. For measuring the traffic density, a correlation technique is presented that for dense traffic uses the radar reflection signals as fingerprints for reidentification of vehicles.

Integrated system of freeway corridor simulation models

Abstract: The newly developed FREQ10 integrated system of freeway corridor simulation models is described with emphasis on traffic simulation, freeway improvement strategies, measures of effectiveness, and traveler responses. The major accomplishments have been to combine the previously developed entry control model, an extensively modified on-freeway priority model, and a newly developed common menu-driven interactive interface into an integrated system of models to extend the types of traffic management strategies that can be evaluated for a freeway corridor. The FREQ10 system of models enables the user to analyze design improvements, implementation of an HOV facility, implementation of normal and priority entry control, or implementation of time-varying capacity reduction situations such as reconstruction activities or freeway incidents. The extensive modifications that have been made to the on-freeway priority model include refining the procedure for traffic simulation, adding many new features such as user-supplied emission and fuel rates, and developing a new method for modeling the arterial and spatial response to reflect current policies that HOV facilities be considered as lanes added to the freeway. This system of models has received extensive testing and has been applied to freeway corridors in several urban areas in California.

Enhancement and field testing of a dynamic freeway simulation program

Abstract: An enhanced version of KRONOS, a dynamic, microcomputer-based freeway simulation program, is presented. KRONOS is based on mesoscopic continuum modeling and explicitly treats the coupling effects of ramps on the freeway flow in detail. The major improvements of the new version include the substantial reduction of computer execution time and the addition of new simulation modules that can describe the flow behavior under restricted capacity situations, such as incidents and short-term construction. Further, a newly developed output interface links KRONOS with other advanced data management and analysis software, so that more detailed and flexible output analysis can be possible. In order to test and validate the program in real traffic environments, field data collection was performed at 26 locations covering an 8-mi section of the I-35W freeway in Minneapolis, Minnesota. The data consist of 5-min volume and speed information for each lane during three morning and three afternoon peak periods. The test results with the available data indicate satisfactory performance of the enhanced KRONOS program in light-to-moderate traffic conditions, although the error increased during heavy congestion.

Evaluation of control strategies through a doubly dynamic assignment model

Abstract: A within-day and day-to-day dynamic assignment model for a general network has been proposed recently. The model follows a nonequilibrium approach, in which flow fluctuations are modeled as a stochastic process. It includes a model of dynamic network loading for computing within-day variable arc flows from path flows. In this paper, the sensitivity and the operational characteristics of the model are tested by analyzing some effects of control measures on a small realistic network. The results of these applications show that the proposed model is a valid tool to estimate the effectiveness of some traffic engineering measures and informative systems. It also appears that some control measures cannot be assessed correctly without the explicit simulation of the demand elasticity over departure times and of the day-to-day adjustment process determined by users' memory and forecasting.

Full-scale accelerated pavement testing for the texas state department of highways and public transportation

Abstract: In 1988 the Texas State Department of Highways and Public Transportation initiated a study to develop a strategy to acquire a mobile accelerated pavement testing device Many methods were evaluated, and the mobile load simulator (MLS) was selected for future application on pavements in Texas The MLS, for which a provisional patent exists, incorporates a method of accelerated load application different from existing mobile accelerated pavement testers A higher degree of traffic simulation and much higher production rates are attainable with the proposed MLS The role of accelerated pavement testing in Texas and the degree of real traffic simulation of the proposed MLS are evaluated A methodology for including environmental effects in accelerated pavement testing is presented

Reliability of real-time information systems for route choice decisions in a congested traffic network: Some simulation experiments

Abstract: This paper investigates the reliability of information on prevailing trip times on the links of a network as a basis for route choice decisions by individual drivers. It considers a type of information strategy where no attempt is made by some central controller or coordinating entity to predict what the travel times on each link would be by the time it is reached by a driver that is presently at a given location. A specially modified model combining traffic simulation and path assignment capabilities is used to analyze the reliability of the real-time information supplied to the drivers. This is accomplished by comparing the supplied travel times (at the link and path levels) to the actual trip times experienced in the network after the information has been given. Results of a series of simulation experiments under recurrent congestion conditions are discussed, illustrating the interactions between information reliability and user response.

An object-oriented traffic simulation with IVHS applications

Abstract: Many traffic simulation models have been developed over the years; however, most existing models are not well-suited for evaluating Intelligent Vehicle/Highway Systems (IVHS) concepts. This paper describes a new model, the Vehicular Traffic Analysis Capability (VTAC), specifically designed to model Advanced Traffic Management and Advanced Traveler Information systems. The model was developed using object-oriented analysis and design principles, and implemented in a relatively new, object-oriented, simulation language. VTAC is believed to be the first traffic model developed using the object-oriented paradigm. The principles used in the new model's design and the preliminary results obtained to-date are described. The model can currently model arterial networks, and sufficient progress has been made to demonstrate the utility of the object-oriented approach to traffic modeling.

Integrating GIS, simulation and animation

Abstract: The author describes techniques for combining the strengths of geographical information systems (GISs), microscopic simulation, and computer animation. A simulation system integrated with an existing GIS to provide the user with the capability of accessing and managing the information transfer between the GIS and the simulation models is described. This integrated system need not be limited to simulation alone; other calculations which are essential for the traffic engineer can be integrated as well. For example, the calculation of highway capacity is a basic need of all traffic engineers. The software to perform these calculations can, itself, be integrated with the GIS system, traffic simulation, and animation. Such a system offers the engineer a capability that goes beyond analysis: the engineer can now perform designs of a system exploring alternative treatments to identify the most effective technique for improving traffic operations. >

Supporting routines for modelling the traffic responsive features of the TravTek system using integration

Abstract: The INTEGRATION simulation model is being enhanced and applied at Queen's University, on behalf of General Motors Research Labs, as a tool to perform a dynamic traffic simulation study of the TravTek route guidance experiment in Orlando, Florida While there were several different ways in which the INTEGRATION model itself was adapted, to be able to model the dynamic and route guidance features of the TravTek system, this paper focusses specifically on describing the associated dynamic modelling routines which needed to be modified and/or developed in order to generate the dynamic inputs to the INTEGRATION model The objective of this paper is to describe the need and role of these supporting routines and to illustrate that the quality of the TravTek simulation study results are ultimately highly dependent on the capability of the supporting routines to properly generate the extensive dynamic input data that are required to properly utilize dynamic traffic simulation models such as INTEGRATION

Toward intelligent traffic signal design system

Abstract: A framework for an intelligent traffic signal design system, incorporating both expert system technology as well as conventional programming techniques, is presented. This system will help less trained engineers and traffic personnel achieve optimal traffic signal designs by closely mimicking the design process of experts in the field. As the first stage of development, an expert system is evolved to suggest phase plans for intersections to be signalized. The representation of the knowledge and the strategy used to arrive at phasing patterns are discussed.

A Dynamic Modelling Framework of Real-Time Guidance Systems in General Urban Traffic Networks

Abstract: There is considerable interest around the world in developing and implementing realtime driver information and/or guidance systems to reduce congestion in the urban traffic networks. However most of these attempts have proceed without much insight into the significant influence of many of the key elements and phenomena involved in a traffic system under information that could determine the effectiveness of alternative designs of such systems. These include: the context, extent and form of the information provided to the drivers, the response and compliance of the drivers to the information, the system-wide implications of particle equipping of the vehicle population, frequency of information update, etc. In this paper a simulation-based framework that incorporates these elements is presented along with illustrative results on its application to realistically sized networks. The traffic simulation is performed using macroscopic local speed-flow relations in discretized segments, while individual drivers' route choice decisions are modelled at the network nodes. The network path processing is based on k-shortest path tree-building that allows the drivers to select among several competing route. Efficient data structures are utilized for storing the network and the k-shortest paths are found using efficient binary heap-sorting procedures. The program can simulate networks with only a fraction of the drivers receiving information. The driver route switching behavior is based on candidate mechanisms of choosing to stay on a route unless an alternative route becomes sufficiently attractive. In addition, the model can also be used to evaluate the effectiveness of guidance instructions provided by a central controller. Simulations are carried out for different behavioral model parameters as well as for different fractions of drivers with information, the results of which are provided with a discussion of substantive conclusions and key insights. The simulations are carried out on a supercomputer, and the advantages of vector processing are also discussed.

Capacity and level of service by simulation--a case study of traf-netsim. highway capacity and level of service. proceedings of the international symposium on highway capacity, karlsruhe, germany, 24-27 july 1991

Abstract: We explore the prospect of using TRAF-NETSIM, a microscopic simulation model, to estimate capacity and level of service through a case study. In the case study, we collected stopped delay, saturation flow, bus dwell time, double parking duration, vehicle and pedestrian volumes, etc. These data served as the bases to run and to calibrate the model, and to check the model results. Although TRAF-NETSIM does not provide capacity and level of service directly, we showed how to make use of its detail simulation capabilities and graphics to obtain capacity and level of service. We also showed how to calibrate the model to represent local traffic conditions. The simulated capacity, stopped delay and level of service were very close to the field results. Since TRAF-NETSIM is a stochastic model, there is concern that its results may vary. We examined its variability by inputting different random number seeds with different simulation times. We find that the variation of capacity was insignificant while that of stopped delay was mixed. We also examined the required number of runs and length of simulation times to obtain 95% level of confidence. TRAF-NETSIM has many advantages. Its animated and static graphics can show what is going on or how the result is derived. Its numerous calibrating parameters enable it to be applicable to many traffic conditions. It produces many statistics which are useful for other analyses. It considers individual factors as well as the interaction of different factors which may affect capacity and level of service. One can analyze the impacts of these factors on one intersection or on the network as a whole. The prospect of using a simulation model such as TRAF-NETSIM for capacity and level of service appears to be promising.

Probability-based load models of highway traffic

Abstract: Keywords: 252/ICOM Reference ICOM-ARTICLE-1991-002doi:10.2749/101686691780617797 Record created on 2008-01-24, modified on 2016-08-08

Model calculation of environment-friendly traffic flows in urban networks

Abstract: The environmental impact of traffic flows in urban networks is an increasingly serious problem. The possibilities are investigated of modifying route choice of traffic in urban networks to meet the standards for noise annoyance and the emission of pollutants. Therefore, for each link of the network an environmental capacity is defined, being the minimum capacity of a link resulting from the selected environmental standards. The maximum flow on a link is defined by the minimum of the environmental capacity and the free flow capacity. By assigning the traffic to the network using the equilibrium assignment technique, a desired pattern of flows is obtained that meets the environmental standards as far as possible. The model is applied to the network of the town of Ede-Bennekom, the Netherlands.

The use of micro simulation for the design of weaving sections. highway capacity and level of service. proceedings of the international symposium on highway capacity, karlsruhe, germany, 24-27 july 1991

Abstract: In the Netherlands the American Highway Capacity Manual (HCM) is commonly used for traffic engineering purposes. Because of the differences in traffic legislation and driver behaviour between the Netherlands and the USA, the HCM cannot be used for the design of weaving sections on Dutch freeways. To create a new set of standards for weaving sections, the micro simulation model FOSIM is used. FOSIM is developed in the USA for simulation of traffic flow on multi-lane freeways and is fully revised for use in the Netherlands. The paper presents the results of calibration and validation of FOSIM for weaving sections on Dutch freeways. Moreover, it describes a method of using FOSIM as a tool to create up to date standards for all sorts of freeway sections.

Special-purpose parallel computer for traffic simulation

Abstract: Traffic simulations are widely used for long- and medium-term forecasting of traffic. Now-a-days, with the growing problem of queues during rush hours, the demand arises for dynamic traffic management and, therefore, short-term forecasting. Apart from the need for new, adapted dynamic assignment models the second important part in this new development is the required computational power. Most commercially available computers are unable to produce an accurate forecasting for the next 5 to 30 min. within the desired time and budget. Analysis of existing assignment models and their most time consuming part--shortest path finding--has shown that the main structure of the models can be parallelized. The use of parallelism thus seems apparent. Several general purpose parallel computers, such as N-cubes, are commercially available. However, apart from being more expensive they loose a large part of their expected performance by the amount of necessary interprocessor communications. Additionally, the programming of such computers has turned out to be more difficult than expected. A simple linear array of typically 16 processors, the so called Linear Processor Array (LPA) is proposed. This one-dimensional parallel computer with high-speed buffered interconnections between each pair of neighboring processor boards, parallel accessible by both a control board and a general-purpose host computer, forms a transparent concept for the programmer. The optimally configured boards together with the high speed intercommunication allow a cost/performance improvement factor of 100 compared with a minisupercomputer like the Convex C1. LPA should be a powerful tool for future developments of on-line traffic control, route guidance, ramp metering, among other things.

Assessment of the traffic experimental and analysis simulation computer model using field data

Abstract: Computer simulation techniques and their applications to traffic operations have gained popularity in recent years. The traffic experimental and analysis simulation (TEXAS) computer model is a prime example. This model was developed to be used as a tool to evaluate traffic performance at isolated intersections operating under various types of intersection control. The objective of this study was to assess the ability of the TEXAS model in simulating isolated signalized intersections. This assessment was conducted using field data. Eight intersection conditions were used for data collection. Existing field data were obtained from previous studies and supplemented with more data collection where needed. Critical 10-min time periods were chosen for the simulation runs, and the average stopped delays obtained from simulation were compared with the observed stopped delay data. Statistical tests were conducted; the results indicated that in most of the intersection conditions no significant difference was observed for through traffic. However, significant differences between field and simulated results were achieved for left-turning traffic. These findings were limited to eight intersection conditions studied in Arizona, and it suggests that the user of the model is advised to carefully assess the default variables embedded in TEXAS.

FREEVU - a computerized freeway traffic analysis tool

Abstract: FREEVU (Freeway Evaluation with Visual Understanding) is a personal computer simulation model intended for freeway design and analysis. It allows the user to specify a freeway section, including lanes, grades, exits and entrances, posted speed limits, and detector locations. The section can then be viewed to confirm the proposed design. A variety of traffic situations can be specified, including percentage trucks, distribution of car and driver characteristics, and entrance and exit percentages. The user can simulate the traffic situation for various freeway design alternatives and then evaluate the design through two methods. First, the information from the specified detector locations can be used to evaluate average volumes, speeds, and densities over time. Second, an animation of the simulation results can be viewed to evaluate weaving sections, stability of traffic flow, impacts of trucks, and so forth. The model is a descendent of the simulation models INTRAS and FOMIS. As in these two models, vehicle movement is based on classic car-following theory and collision-avoidance restrictions. However, FREEVU also incorporates behavioral lane changing algorithms and vehicle performance constraints. FREEVU is user-friendly with extensive menus and default values. The simulation model has been evaluated using different sites and was generally found to represent simulation traffic flow accurately.

Cross-section elements to accommodate passing lanes and vehicle storage during avalanche control for the trans-canada highway in rogers pass

Abstract: The paper presents the results of a study of the Trans-Canada Highway through Mount Revelstoke and Glacier National Park. The study is based on the fact that traffic flow characteristics, highway conditions, and operational requirements vary considerably from season to season. Thus, the analysis was broken into 2 parts: a separate analysis of winter and summer conditions. A traffic simulation model was used to determine those locations that could serve as potential sites for passing lanes during summer. The traffic simulation model for the passing lane analysis utilized files that describe road geometry, summer traffic flow and composition, and vehicle performace. A separate simulation model was developed to determine ponding areas during avalanche control. The paper concludes with a general discussion on the benefits of linking traffic simulation with geometric design to demonstrate how the design life of rural 2-lane highways can be extended by the use of low-cost operational improvements such as passing lanes.

Traffic flow simulation through parallel processing. final research report

Abstract: Explicit numerical methods for solving macroscopic traffic flow continuum models have been studied and efficiently implemented in traffic simulation codes. We studied and implemented implicit numerical methods for solving the flow conservation traffic model. We then wrote an experimental code in C simulating a freeway (un)congested pipeline and freeway entry/exit traffic flow. Tests with real data collected from the I-35 W freeway in Minneapolis were conducted on a workstation computer. The implicit methods gave the same (and in some cases better) accuracy as the Lax method. The implicit methods were (more than twice) faster than the Lax method. We also implemented the Lax method on a parallel machine and obtained significant execution time reduction.

Us-75 north central expressway reconstruction: pre-construction traffic conditions. interim report

Abstract: This report documents the development and implementation of the traffic monitoring plan for the North Central Expressway Corridor. The report also provides a summary of the travel time and volume data collected during October 1989 and May 1990, as well as the vehicle occupancy and classification studies conducted during May 1990. The primary purpose of these two studies is to provide a pre-construction traffic database. These data will aid in monitoring the changes in traffic conditions that might occur in the North Central Expressway Corridor as a result of construction. These studies are also intended to aid in the following: (1) traffic management planning for future phases of the North Central Project and for future projects in the Dallas area, (2) development of optimal signal timing plans for the arterial streets in the corridor, (3) public affairs programs which inform the public about traffic conditions and travel alternatives, (4) DART bus route and schedule planning, and (5) validation of portions of the North Central Texas Council of Government peak hour traffic model.

Traffic patterns in unstable traffic flow on freeways. highway capacity and level of service. proceedings of the international symposium on highway capacity, karlsruhe, germany, 24-27 july 1991

Abstract: To explain the different traffic patterns for very dense traffic on freeways like spreading shock fronts, irregular stop-start waves, bistability and hysteresis phenomena, a dynamic traffic model is presented This model shows, depending on essentially two control parameters, the quoted variety of different traffic patterns The patterns are derived as stationary profiles for regular stop-start waves and stable running shock waves and as transients approaching the stationary profiles as bifurcation with supercritical or subcritical dependence on the two control parameters, namely bottleneck capacity and mean density Finally irregular motion examples are given These irregularities are explained by means of chaos theory similar to the turbulence description of fluid motion Freeway traffic control for dense traffic needs besides a traffic flow model advanced technologies for detection of section related traffic variables As nonlocal measurement technique which uses a correlation method between neighboured measurement sites a mm-wave radar set up is described

Red routes in richmond

Abstract: In 1989, a proposal was made to designate certain, predominantly radial roads into London as Red Routes. On these routes stopping or parking at peak hours of the day would be severely restricted. This study was undertaken to provide a database against which to quantify the potential benefits of the Red Route proposals.