Download or read book Development and Testing of Variable Speed Limit Control Logics for Work Zones Using Simulation written by Byungkyu Park and published by . This book was released on 2003 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been a considerable increase in the amount of construction work on the U.S. national highways in recent years. This is a direct result of the current transportation policies emphasis on the maintenance of existing facilities rather than on building new ones. But with the increase in the amount of traffic on the interstates, the safety at the construction sites is getting worsened. Variable speed limit (VSL) systems are a kind of intelligent transportation systems (ITS) technology and they try to increase safety by posting the maximum or minimum speed limits. The speeds to be posted on the VSL signs are calculated manually or with the help of algorithms. This study is an attempt to evaluate the performance of various speeds at work zones and to develop VSL control logics that would calculate suitable speeds for different traffic conditions. The research is conducted by simulating a postulated test-bed network and then validating the results by simulating a real world work zone site. The study uses a microscopic simulation model - VISSIM. The study developed a safety surrogate measure, minimum safety distance equation (MSDE), to quantify safety. Travel times have primarily been used to quantify mobility. Since most of the existing VSL control logics consider only the traffic advisory speed or average traffic speed, an attempt was made to develop a logic that would consider both safety and mobility in calculating speeds. The results of simulating the postulated network indicated that the performance of speeds varied with traffic demand volumes and compliance rate conditions. In general an increase in speed decreased safety, but improved travel time. Surprisingly at low volume and low compliance conditions an increase in speed also improved safety. In order to find the speeds that provide optimal measures of safety and mobility a normalization procedure that combines travel time and safety measures is used. The performance of the logics is mixed. In general logic 3 (that considers both safety and mobility measures to calculate VSL speed) performed better than logics 1 and 2 (that use average traffic speed). However logics 1 and 2 performed better than Logic 3 for oversaturated conditions and for low volume and low compliance conditions. Statistical analysis was performed to substantiate the results of the base cases and the logics. The performance of the VSL system was also evaluated by simulating a real world work zone site at Covington, Virginia. The results were found to be consistent with those of the postulated network.

Download or read book Evaluation of Variable Speed Limits in Work Zones written by Disapat Lavansiri and published by . This book was released on 2003 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Work Zone Variable Speed Limit Systems written by Nicholas J. Fudala and published by . This book was released on 2010 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Variable speed limit (VSL) systems have been used in a number of countries, particularly in Europe, as a method to improve flow and increase safety. VSLs use detectors to collect data on current traffic and/or weather conditions. Posted speed limits are then dynamically updated to reflect the conditions that motorists are actually experiencing. Presenting drivers with speed limits that are appropriate for current conditions may reduce speed variance, a concept sometimes called speed harmonization. If properly designed, VSL systems have been shown to reduce crash occurrence and can also reduce system travel time through increased uniformity in traffic speeds. High-volume urban work zones tend to be prone to congestion and safety problems, and VSLs may be one way to ameliorate these issues. VSLs were recently installed at a high-volume, congested urban work zone located on I-495 (the Capital Beltway, hereinafter the Beltway) between the Springfield Interchange in Springfield, Virginia, and the Virginia-Maryland state line on the Woodrow Wilson Memorial Bridge. VSL signs were activated in late July 2008, but initial evaluations of the system showed inconclusive effects. Changing site conditions made a direct before-and-after evaluation of the system deployed in the field problematic, and some problems with the control algorithm were also noted. Given the difficulties in evaluating the system deployed in the field, a calibrated simulation of the site was constructed to assess the effects of the VSL system on traffic operations and safety surrogate measures. The simulation platform also provided an opportunity to examine a number of system configurations to assess how changes in system design and driver behavior might affect a variety of measures. The results indicated that the VSL could create substantial improvements in traffic operations provided the demand did not exceed capacity by too large a margin. The location of the VSL signs played an important role in operational performance. The study recommends that the Virginia Department of Transportation continue to pursue this technology but carefully scrutinize algorithm design and VSL sign placement. Further, a cost/benefit analysis indicated that VSLs may be most appropriate for long-term applications.

Download or read book A Highway Work Zone Design and Traffic Management Decision System written by Yali Chen and published by . This book was released on 2008 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mobility and Safety Evaluation of Integrated Dynamic Merge and Speed Control Strategies in Work Zones written by Syed Muhammad Zaier Abbas Zaidi and published by . This book was released on 2010 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, there has been a considerable increase in the amount of construction work on the U.S. national highways. Most of the work undertaken is the reconstruction and rehabilitation of the existing transportation networks. Work zones in the United States are likely to increase in number, duration and length due to emphasis on repair and highway reconstruction as a significant portion of all federal-aid highway funds are now geared toward highway rehabilitation. The challenge of mobility is particularly acute in work zone areas as road repair and construction intensifies traffic issues and concentrates them in specific locations and at specific times. Due to the capacity drop, which is the result of lane closure in work zone area, congestion will occur with a high traffic demand. The congestion increases number and severity of traffic conflicts which raise the potential for accidents; furthermore traffic operational properties of roadway in work zone area become worse. Intelligent Transportation System (ITS) technologies have been developed and are being deployed to improve the safety and mobility of traffic in and around work zones. In several states in the US, the use of Dynamic Merge Controls also known as Dynamic Lane Merge (DLM) system has been initiated to enhance traffic safety and to improve traffic flow in work zone areas. The DLM usually takes two forms; dynamic early merge and dynamic late merge. The use of variable speed limit (VSL) systems at work zones is also one of those measures. VSL systems improve safety by helping the driver in determining the maximum speed that drivers should travel. Besides adding improvement to safety, they are also expected to improve mobility at the work zones. The main goal of this study is to evaluate the safety and operational effectiveness of the dynamic merge systems i.e. the dynamic early lane merge and dynamic late lane merge, in the presence of VSL system. More specifically, the VISSIM model is utilized to simulate a two-to-one lane configuration when one out of the two lanes in the work zone is closed for traffic. Six different scenarios were adopted to assess the effectiveness of these scenarios under different traffic demand volumes and different drivers' compliance rates to the messages displayed by the systems. These scenarios are; [bullet] Work Zone without VSL and without SDLMS or the current Motorist Awareness System (MAS) [bullet] Work Zone with VSL and without SDLMS [bullet] Work Zone with VSL and Early SDLMS [bullet] Work Zone with VSL and Late SDLMS [bullet] Work Zone with early SDLMS and without VSL [bullet] Work Zone with early SDLMS and without VSL An already calibrated and validated VISSIM model for Simplified Dynamic Lane Merge System (SDLMS) in accordance with the real life work zone was modified with a VSL through Vehicle Actuated Programming (VAP) code. Three different logics were coded each for VSL alone, early SDLMS+VSL and late SDLMS+VSL. All these logics were fine tuned with several test runs before finalizing it for the final simulation. It is found through the simulation of above mentioned scenarios that for low and medium volume levels (V0500, V1000 and V1500), there is no significant difference between the Maintenance of Traffic (MOT) plans for mean throughputs. However, for higher volume levels (V2000 and V2500), late SDLMS with and without VSL produced higher mean throughputs for all compliance rates and truck percentages except when the demand volume was 2,500 vph and compliance of 60%, where it produces the significantly lower mean throughputs. In terms of travel time through the work zone, results indicated that there is no significant difference between MOT types for demand levels of V0500 and V1000 when compliance is 40% or less but for compliance of 60% and more, only demand volume level that is not significantly different from other MOT types is V0500. This study revealed that VSL increases travel time through the work zone. This might be due to non-compliant vehicles that follow the compliant vehicle ahead unless they find a sufficient gap in adjacent lane to pass the compliant vehicle. It is also found out that VSL makes the system safer at higher volumes (2,000 vph and 2,500 vph). This was observed through safety surrogate measures selected for this study. Another outcome of this study is that the addition of VSL to the dynamic merge systems helps in improving the overall safety of the system by lowering speed variances and deceleration means of the vehicles travelling through the work zone. The passage of traffic through the work zone is made safer when a speed control is integrated to a dynamic merge system. It can be inferred from the simulation results that integrated SDLMS and VSL systems have better performance in terms of traffic mobility and safety than existing individual controls and also show that the integrated SDLMS and VSL system has more potential than each individual systems.

Download or read book Implementing Active Traffic Management Strategies in the U S written by Virginia P. Sisiopiku and published by . This book was released on 2009 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Using Connected Vehicles in Variable Speed Limit Systems written by Ellen F. Grumert and published by Linköping University Electronic Press. This book was released on 2018-04-10 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Motorway traffic management systems are useful for improving the traffic conditions on urban motorways. One of the most common motorway traffic management systems are variable speed limit systems. These systems adapt the speed limits based on the prevailing traffic conditions measured by roadside detectors and recommended or compulsory speed limits are shown on variable message signs installed on gantries over the road.Thesystems consist of three parts; the control algorithm used to determine which speed limit to be displayed, a method for estimating the traffic conditions to be used as input for the control algorithm and the infrastructure for application of the variable speed limits. The goal of the systems is often to increase safety or efficiency. Recent development in the field of connected vehicles have opened up for a new type of data source, as the status of a connected vehicle and its surroundings can be communicated at arbitrary locations. Hence, by the use of connected vehicles in variable speed limit systems there is a potential of reducing the amount of roadside equipment. It is even possible to control the connected vehicles towards the current speed limit without the use of variable message signs. This allows for the application of variable speed limits at arbitrary locations. The aim of this thesis is to examine how connected vehicles can be used to improve the efficiency of variable speed limit systems. The thesis contribute with new and improved methods using connected vehicles in all three parts of a variable speed limit system. The suggested methods are evaluated by microscopic traffic simulation. The overall conclusion is that the use of connected vehicles in variable speed limit systems can contribute to improvements in traffic efficiency compared to existing systems. The six papers included in the thesis can be summarized as follows. First, it is shown that traditional variable speed limit systems can be effective for improving the traffic conditions on the motorway and the results can be comparable to more costly alterations by reconstruction of the infrastructure to increase the capacity. Next, the usefulness of connected vehicles for application and control of the speed limits in an existing variable speed limit system is investigated. It is concluded that the design of the control algorithm and the accuracy of the estimated traffic conditions have a great effect on the final outcome of the system. The design of the control algorithm is then examined by evaluation of a number of control algorithms with respect to safety, efficiency and environmental impacts. The main benefits and drawbacks of the algorithms are highlighted and desirable characteristics to include when designing a control algorithm are identified. In two studies, methods making use of connected vehicles for estimating the traffic conditions are proposed. The results show that connected vehicles are useful for improving the accuracy of the estimated traffic conditions through the inclusion of more detailed information and information at locations where detector measurements are not available. Finally, a variable speed limit system is proposed in which connected vehicles play a central role in the estimation of the traffic conditions, as well as in the control algorithm and for application of the speed limit. The system is shown to be useful for improving traffic efficiency during an incident at an arbitrary location along the controlled road.

Download or read book Investigation of Solutions to Recurring Congestion on Freeways written by Nicholas J. Mazzenga and published by . This book was released on 2009 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Persistent daily congestion, which has been increasing in recent years, is commonly experienced for several hours or more during the morning and evening on Virginia's urban freeways. Many of these roadways are at or near capacity, which causes severe delays and backups. One solution to reducing recurring congestion is to add capacity by building more lanes; however, this is usually the last resort as it is an expensive and time-consuming approach. Another strategy proposed to combat recurring congestion is to manage the current freeways so that they operate more efficiently. Reducing congestion through better managed freeways has numerous documented benefits, including reducing travel times, smoothing the traffic flow, increasing average fuel economy, shortening the rush hour period and reducing vehicle queuing. The highway operational strategies implemented to reduce recurring congestion have shown promising results abroad where there is an extensive use of active traffic management systems. To prove the effectiveness of a better managed freeway in mitigating recurring congestion, this study tested the effectiveness of an active traffic management system on a simulated model of I-66 and I-95 in Northern Virginia. Hard shoulders, variable speed limits, and ramp metering are several active traffic management systems simulated in this study. The simulation model was based on the geometric characteristics, ramp volumes, vehicle flows, and speeds of actual recorded conditions. Compared with the simulated control conditions, the results of the study indicated improvements in average fuel economy, travel delay, delay of the onset of congestion, and reduction of queues. The two active traffic management systems, i.e., variable speed limits and hard shoulders, showed the highest potential for reducing recurring congestion and should be considered as potential countermeasures in congested corridors. Although the capital costs of implementing these strategies would be high, the return on investment in the first year of operations is estimated at $500,000, with the potential to grow to as much as $8 million annually in subsequent years.

Download or read book Work Zone Speed Analysis Using Driving Simulator Data written by Arash Adeli and published by . This book was released on 2014 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigates drivers' behavior in the highway work zone by incorporating virtual data collected by a high fidelity driving simulator. The study specifically examined speed variations along the work zone and compliance with the speed limit. A large network of 154 square miles southwest of Baltimore was developed in driving simulator. Over 100 participants from different socioeconomic groups were recruited to run driving tests under the study scenarios. Speed analysis was performed in both aggregate and disaggregate levels in work zone and in the areas under the influence of work zone related signs. The results demonstrate that drivers significantly comply with the speed limit in work zone and reduced their speed as they approached the work zone. Evaluation of speed limit violators confronting the work zone and its associated signs reveals that the majority of speed limit violators comply with the speed limit. Age, road familiarity and experience had a significant impact on speed limit compliance in the work zone while education level, income level and gender didn't reveal a clear association. Study results showed that although most of the drivers increased their speed immediately after passing the work zone, the compliance rate with the speed limit increased in comparison with the upstream zone, which demonstrate a sustainable effect of work zone and its associated signs on speed limit compliance behavior. The findings of this study could benefit transportation agencies for proper design of work zones and practice to increase safety for workers and drivers by predicting driver behavior in work zones. -- Abstract.

Download or read book Determining Major Causes of Highway Work Zone Accidents in Kansas written by Yong Bai and published by . This book was released on 2006 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this research was to investigate the characteristics of fatal crashes and risk factors to these crashes in the work zones so that effective countermeasures could be developed and implemented in the near future. The objective was accomplished using a four-step approach.

Download or read book Variable Speed Limit Signs Effects on Speed and Speed Variation in Work Zones written by Matt Riffkin and published by . This book was released on 2008 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technological advances allow speed limits to be changed in real time based on actual roadway conditions. There may be potential advantages to using variable speed limits in Utah, such as for traffic control during construction where the speed limit may be lowered adjacent to actual construction activities versus at other times or locations within an established work zone. This research will test the compliance and derive potential advantages from the use of variable speed limit equipment.

Download or read book Fuzzy Variable Speed Limit Device Modification and Testing Phase II written by John Placer and published by . This book was released on 2001 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes a project which focused on the upgrading of a Road Weather Information Station (RWIS) site on I-40 in Arizona. The objective was to have the RWIS site function as a test site for monitoring the complete data set of atmospheric and road surface conditions that can be utilized by a fuzzy control algorithm. A secondary objective was to enhance the site so that it would also supply traffic flow data.

Download or read book Evaluation of Variable Advisory Speed Limits in Work Zones written by Praveen Edara and published by . This book was released on 2012 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: Variable advisory speed limit (VASL) systems could be effective at both urban and rural work zones, at both uncongested and congested sites. At uncongested urban work zones, the average speeds with VASL were lower than without VASL. But the standard deviation of speeds with VASL was higher. The increase in standard deviation may be due to the advisory nature of VASL. The speed limit compliance with VASL was about eight times greater than without VASL. At the congested sites, the VASL were effective in making drivers slow down gradually as they approached the work zone, reducing any sudden changes in speeds. Mobility-wise the use of VASL resulted in a decrease in average queue length, throughput, number of stops, and an increase in travel time. Several surrogate safety measures also demonstrated the benefits of VASL in congested work zones. VASL deployments in rural work zones resulted in reductions in mean speed, speed variance, and 85th percentile speeds downstream of the VASL sign. The study makes the following recommendations based on the case studies investigated: 1. The use of VASL is recommended for uncongested work zones to achieve better speed compliance and lower speeds. Greater enforcement of regulatory speed limits could help to decrease the standard deviation in speeds; 2. The use of VASL to complement the static speed limits in rural work zones is beneficial even if the VASL is only used to display the static speed limits. It leads to safer traffic conditions by encouraging traffic to slow down gradually and by reminding traffic of the reduced speed limit. A well-designed VASL algorithm, like the P5 algorithm developed in this study, can significantly improve the mobility and safety conditions in congested work zones. The use of simulation is recommended for optimizing the VASL algorithms before field deployment.

Download or read book Statistical Methods and Safety Data Analysis and Evaluation written by National Research Council (U.S.). Transportation Research Board and published by . This book was released on 2004 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamentals of Traffic Simulation written by Jaume Barceló and published by Springer Science & Business Media. This book was released on 2011-01-06 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing power of computer technologies, the evolution of software en- neering and the advent of the intelligent transport systems has prompted traf c simulation to become one of the most used approaches for traf c analysis in s- port of the design and evaluation of traf c systems. The ability of traf c simulation to emulate the time variability of traf c phenomena makes it a unique tool for capturing the complexity of traf c systems. In recent years, traf c simulation – and namely microscopic traf c simulation – has moved from the academic to the professional world. A wide variety of traf- c simulation software is currently available on the market and it is utilized by thousands of users, consultants, researchers and public agencies. Microscopic traf c simulation based on the emulation of traf c ows from the dynamics of individual vehicles is becoming one the most attractive approaches. However, traf c simulation still lacks a uni ed treatment. Dozens of papers on theory and applications are published in scienti c journals every year. A search of simulation-related papers and workshops through the proceedings of the last annual TRB meetings would support this assertion, as would a review of the minutes from speci cally dedicated meetings such as the International Symposiums on Traf c Simulation (Yokohama, 2002; Lausanne, 2006; Brisbane, 2008) or the International Workshops on Traf c Modeling and Simulation (Tucson, 2001; Barcelona, 2003; Sedona, 2005; Graz 2008). Yet, the only comprehensive treatment of the subject to be found so far is in the user’s manuals of various software products.

Download or read book Improved Work Zone Design Guidelines and Enhanced Model of Travel Delays in Work Zones written by Helmut T. Zwahlen and published by . This book was released on 2006 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: The project focuses on two major issues - the improvement of current work zone design practices and an analysis of vehicle interarrival time (IAT) and speed distributions for the development of a digital computer simulation model for queues and travel delays in work zones. Important considerations in the development of work zone design guidelines include guidance, delineation, and the safety of workers and drivers. A nationwide survey of current work zone best practices was conducted. Based on the review of the existing ODOT guidelines, superior practices available in other states, relevant research, and professional judgment of personnel involved in work zone activities, a set of guidelines for work zone design are proposed. It is anticipated that these research findings will result in the better design of work zones which will minimize traffic delays and improve safety. In the second part of the project trailers, each using two Wavetronix microwave radar units in side-fire mode, were developed to nonintrusively measure traffic. The traffic was measured at six work zones sites with different types of lane configurations at different freeways in Ohio. Traffic on the road was also independently measured using video and radar, and the results compared to records from the trailers to verify that the trailers were measuring the traffic with reasonable accuracy. IAT data of successive vehicles in freeflowing traffic ahead of work zones were analyzed and IAT distributions were generated as a function of the traffic volume for each lane and relationships between traffic volumes and cumulative IAT distributions were established allowing a direct conversion from hourly traffic counts to corresponding cumulative IAT distributions. This conversion method produces fairly accurate cumulative IAT distributions for selected hourly traffic volumes. It was also found that the same cumulative IAT distribution can be used to model the free-flowing traffic at other freeway locations in Ohio, which means that the IAT distributions are portable and scalable and a microscopic digital computer simulation model based on queueing theory may be developed to investigate traffic delays in work zones.

Download or read book Control Logic for the Operation of Rural Variable Speed Limits Subject to Severe Winter Conditions written by Vijay Kumar Sabawat Krishna and published by . This book was released on 2013 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Variable Speed Limit (VSL) systems are an innovative way of managing traffic using Intelligent Transportation Systems (ITS). Unlike the traditional static speed limit signs, VSLs are speed limit signs with a capability of changing regulatory speed limits according to changing real time weather and traffic conditions. VSLs are primarily used to reduce traffic congestion and improve safety along roadways. Wyoming weather is highly variable and often severe, in the absence of recommended speed limits for such conditions drivers select their own safe driving speed leading to high variance among vehicles. This high speed variance, results in high crash rates and frequent road closures. Currently Wyoming Department of Transportation (WYDOT) using an interim manual protocol to deploy speed limits on VSL corridors. A new automated self-learning methodology for deploying VSL is described in this dissertation. As a first step in this project, weather variables that have a significant effect on vehicle speeds during bad weather conditions were identified using a robust regression statistical procedure. Second, an automated control strategy was designed that uses real time weather and observed speed variables. Third, a statistical model called decision trees was used in control strategy to enhance the performance of the automated control strategy. Fourth, a self-learning component is added to the control strategy to address concerns about the high variability of different storm events in this region. The proposed automated self-learning algorithm was tested on previous storm event datasets and results from the simulation indicate that the new system is more efficient than the current manual protocol of deploying speed limits. Finally, the transferability of the proposed control strategy was evaluated by applying the self-learning control strategy that was developed based on the storm data available at the Elk Mountain corridor to the storm data available at Laramie-Cheyenne corridor.