535 research outputs found

    Application of ALINEA ramp control algorithm to freeway traffic flow on approaches to Bosphorus strait crossing bridges

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    AbstractBeginning from the 1960ies sustainability has been being pointed out as an important criterion in development which made many countries plan sustainability originated progressing policies. The decision makers, planning to construct a third roadway bridge to connect Asia and Europe continents on to the Bosphorus in Istanbul metropolitan area, first have to evaluate the exaggerated road traffic congestion phenomenon. Before making such a non-environmentally friend decision, advanced traffic managing strategies have to be incorporated to regularize the current pattern of traffic flows on the existing road network that prevails the road based urban transport.Ramp control is an efficient strategy that has been employed to prevent recurrent traffic congestion since 1970ies. With the employment of ramp control applications, several benefits of ramp management, including i.e., the increase on the level of traffic safety, the increase on travelling speeds and consequently decrease on travelling times, the increase on the level-of-service, increase on energy consumption efficiency, decrease on environmental impacts, and increase on user satisfaction, have been experienced. The present paper aims to impose advanced traffic management schemes, specifically the ramp control, on the non-efficient utilisation of freeway approaches to existing Bosphorus bridges as an alternative to a third bridge crossing

    Illusion of Motion: Variation of Subjective Value of Travel Time on Freeways and Ramp Meters

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    This paper explores drivers' subjective value of time under moving and stopped freeway travel conditions using a stated preference survey. Unlike previous studies that assume a constant value of time, this research relates perceived satisfaction of a freeway trip to its quality indicators. Sixty-nine subjects in the Twin Cities are asked in the survey to rank sixteen driving scenarios in four condition sets with different durations of ramp wait and freeway travel. Several utility functions are specified where the weight of ramp delay is a function of the length of the delay itself and subject specific variables, and the resulting choice models estimated using rank-ordered logit and binary logit techniques. Results suggest that drivers perceive ramp wait as more onerous than freeway travel. Drivers also weight each minute of ramp wait more heavily as the length of the delay gets longer. Although the subjects show some tolerance to the first several minutes of ramp delay (less than 5 minutes), they perceive long delays as much as twelve times more onerous than time in motion. The derived weighting function for ramp wait can improve the design of freeway traffic control strategies that trade-off freeway delay with ramp wait. The findings also enable a more utility-based approach for freeway operations than the current method which has the engineering efficiency objective of minimizing total system delay or maximizing throughput. Minimizing total perceived travel time is probably more appropriate than minimizing total absolute travel time which does not take into account driver acceptance. The weighting function can also be easily transformed into a value of time function for project evaluation purposes.Value of time, value of travel time, Time perception, Driver acceptance, Freeway congestion, Ramp meter

    AN INTEGRATED CONTROL MODEL FOR FREEWAY INTERCHANGES

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    This dissertation proposes an integrated control framework to deal with traffic congestion at freeway interchanges. In the neighborhood of freeway interchanges, there are six potential problems that could cause severe congestion, namely lane-blockage, link-blockage, green time starvation, on-ramp queue spillback to the upstream arterial, off-ramp queue spillback to the upstream freeway segments, and freeway mainline queue spillback to the upstream interchange. The congestion problem around freeway interchanges cannot be solved separately either on the freeways or on the arterials side. To eliminate this congestion, we should balance the delays of freeways and arterials and improve the overall system performance instead of individual subsystem performance. This dissertation proposes an integrated framework which handles interchange congestion according to its severity level with different models. These models can generate effective control strategies to achieve near optimal system performance by balancing the freeway and arterial delays. The following key contributions were made in this dissertation: 1. Formulated the lane-blockage problem between the movements of an arterial intersection approach as an linear program with the proposed sub-cell concept, and proposed an arterial signal optimization model under oversaturated traffic conditions; 2. Formulated the traffic dynamics of a freeway segment with cell-transmission concept, while considering the exit queue effects on its neighboring through lane traffic with the proposed capacity model, which is able to take the lateral friction into account; 3. Developed an integrated control model for multiple freeway interchanges, which can capture the off-ramp spillback, freeway mainline spillback, and arterial lane and link blockage simultaneously; 4. Explored the effectiveness of different solution algorithms (GA, SA, and SA-GA) for the proposed integrated control models, and conducted a statistical goodness check for the proposed algorithms, which has demonstrated the advantages of the proposed model; 5. Conducted intensive numerical experiments for the proposed control models, and compared the performance of the optimized signal timings from the proposed models with those from Transyt-7F by CORSIM simulations. These comparisons have demonstrated the advantages of the proposed models, especially under oversaturated traffic conditions

    Computational Intelligence in Highway Management: A Review

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    Highway management systems are used to improve safety and driving comfort on highways by using control strategies and providing information and warnings to drivers. They use several strategies starting from speed and lane management, through incident detection and warning systems, ramp metering, weather information up to, for example, informing drivers about alternative roads. This paper provides a review of the existing approaches to highway management systems, particularly speed harmonization and ramp metering. It is focused only on modern and advanced approaches, such as soft computing, multi-agent methods and their interconnection. Its objective is to provide guidance in the wide field of highway management and to point out the most relevant recent activities which demonstrate that development in the field of highway management is still important and that the existing research exhibits potential for further enhancement

    Regional Data Archiving and Management for Northeast Illinois

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    This project studies the feasibility and implementation options for establishing a regional data archiving system to help monitor and manage traffic operations and planning for the northeastern Illinois region. It aims to provide a clear guidance to the regional transportation agencies, from both technical and business perspectives, about building such a comprehensive transportation information system. Several implementation alternatives are identified and analyzed. This research is carried out in three phases. In the first phase, existing documents related to ITS deployments in the broader Chicago area are summarized, and a thorough review is conducted of similar systems across the country. Various stakeholders are interviewed to collect information on all data elements that they store, including the format, system, and granularity. Their perception of a data archive system, such as potential benefits and costs, is also surveyed. In the second phase, a conceptual design of the database is developed. This conceptual design includes system architecture, functional modules, user interfaces, and examples of usage. In the last phase, the possible business models for the archive system to sustain itself are reviewed. We estimate initial capital and recurring operational/maintenance costs for the system based on realistic information on the hardware, software, labor, and resource requirements. We also identify possible revenue opportunities. A few implementation options for the archive system are summarized in this report; namely: 1. System hosted by a partnering agency 2. System contracted to a university 3. System contracted to a national laboratory 4. System outsourced to a service provider The costs, advantages and disadvantages for each of these recommended options are also provided.ICT-R27-22published or submitted for publicationis peer reviewe

    An integrated variable speed limit and ALINEA ramp metering model in the presence of High Bus Volume

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    Under many circumstances, when providing full bus priority methods, urban transport officials have to operate buses in mixed traffic based on their road network limitations. In the case of Istanbul’s Metrobus lane, for instance, when the route comes to the pre-designed Bosphorus Bridge, it has no choice but to merge with highway mixed traffic until it gets to the other side. Much has been written on the relative success of implementing Ramp Metering (RM), for example ALINEA (‘Asservissement line´ aire d’entre´ e autoroutie’) and Variable Speed Limits (VSL), two of the most widely-used “merging congestion” management strategies, in both a separate and combined manner. However, there has been no detailed study regarding the combination of these systems in the face of high bus volume. This being the case, the ultimate goal of this study is to bridge this gap by developing and proposing a combination of VSL and RM strategies in the presence of high bus volume (VSL+ALINEA/B). The proposed model has been coded using microscopic simulation software—VISSIM—and its vehicle actuated programming (VAP) feature; referred to as VisVAP. For current traffic conditions, the proposed model is able to improve total travel time by 9.0%, lower the number of average delays of mixed traffic and buses by 29.1% and 81.5% respectively, increase average speed by 12.7%, boost bottleneck throughout by 2.8%, and lower fuel consumption, Carbon Monoxide (CO), Nitrogen Oxides (NOx), and Volatile Organic Compounds (VOC) emissions by 17.3% compared to the existing “VSL+ALINEA” model. The results of the scenario analysis confirmed that the proposed model is not only able to decrease delay times on the Metrobus system but is also able to improve the adverse effects of high bus volume when subject to adjacent mixed traffic flow along highway sections

    Dynamic multi-ramp metering control with simultaneous perturbation stochastic approximation (SPSA)

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    Ramp metering was proven to be a viable form of freeway traffic control strategy, which could eliminate, or at least reduce, freeway congestion. In this study, the development of ramp metering control strategies, models, and constraints (e.g., meter locations, ramp storage capacities, lower and upper bounds of ramp metering rates) are discussed in detail. The pre-timed and demand/capacity metering control strategies were first evaluated, while the potential metered ramps were determined. A Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm is proposed to dynamically optimize multiple-ramp metering control by maximizing the total throughput subject to a number of constraints. The ramp metering rates subject to dynamic traffic conditions and capacity constraints are considered as decision variables in the SPSA algorithm. Based on the collected geometric and traffic data, a CORSIM model was developed to simulate traffic operation for the study site. The potential benefit of the dynamic multi-ramp metering control model under time varying traffic condition was simulated and evaluated. The increased total throughput and reduced total delay were observed, while the traffic conditions suitable for implementing ramp metering control were suggested. The developed dynamic multi-ramp metering control with SPSA algorithm has demonstrated its effectiveness to improve freeway operation

    Ramp metering and freeway bottleneck capacity

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    The objective of this study is to determine whether ramp meters increase the capacity of active freeway bottlenecks, and if they do, how. The traffic flow characteristics at twenty-seven active bottlenecks in the Twin Cities have been studied for seven weeks without ramp metering and seven weeks with ramp metering. A series of hypotheses regarding the relationships between ramp metering and the capacity of active bottlenecks are developed and tested against empirical traffic data. It is found that meters increase the bottleneck capacity by postponing and sometimes eliminating bottleneck activations (a 73 percent increase in the duration of the pre-queue transition period), accommodating higher (2 percent) flows during the pre-queue transition period, and increasing queue discharge flow rates after breakdown (3 percent). The two-capacity hypothesis about flow drops after breakdown was also examined and results strongly suggest the percentage flow drops at various bottlenecks follow a normal distribution (mean 5.5 percent, standard deviation 2.3 percent). The implications of these findings on the design of efficient ramp control strategies are discussed, as well as future research directions.transportation, travel behavior, congestion, ramp meters
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