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Author: Mutasem Alzoubaidi
Publisher:
ISBN:
Category : Intelligent transportation systems
Languages : en
Pages : 139
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Book Description
Innovative intersections and interchange designs is one strategy known to enhance the operational and safety performance of our roads. Innovative designs specifically lead to an improved signal progression and result in reduced travel times, delays, crash severities and frequencies. Connected Vehicle (CV) technology is another strategy that has enabled dozens of Intelligent Transportation Systems (ITS) applications with the potential to bring major safety, mobility and environmental benefits. Many studies have focused on exploring each strategy when implemented solely. Therefore, one of the goals of this dissertation is studying the impacts and benefits of the combined implementation of the two strategies, while the other lies within developing a new innovative interchange design called the Continuous Green-T Partial Cloverleaf A (CGT-parclo A) and exploring its operational and safety aspects. A microsimulation approach was followed to achieve these goals.The results show that the combined implementation of CVs and innovative intersections has reduced travel times, and delays by nearly 65.3%, and 29.2%, respectively. Additionally, the total number of conflicts, rear-end and lane change conflicts dropped by nearly 23.8%, 23.6% and 24.4%, respectively at full Continuous Flow Intersections and 100% MPRThe CGT-parclo A exhibited superior operational performance to a multitude of interchange designs in most tested cases. The CGT-parclo A reduced travel times, and delays as high as 55.7%, and 69.8%, respectively, compared to the parclo A and parclo progressA. The CGT-parclo A is the best form of parclo A interchanges in terms of reducing the likelihoods, severities and frequencies of crashes.
Author: Mutasem Alzoubaidi
Publisher:
ISBN:
Category : Intelligent transportation systems
Languages : en
Pages : 139
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Book Description
Innovative intersections and interchange designs is one strategy known to enhance the operational and safety performance of our roads. Innovative designs specifically lead to an improved signal progression and result in reduced travel times, delays, crash severities and frequencies. Connected Vehicle (CV) technology is another strategy that has enabled dozens of Intelligent Transportation Systems (ITS) applications with the potential to bring major safety, mobility and environmental benefits. Many studies have focused on exploring each strategy when implemented solely. Therefore, one of the goals of this dissertation is studying the impacts and benefits of the combined implementation of the two strategies, while the other lies within developing a new innovative interchange design called the Continuous Green-T Partial Cloverleaf A (CGT-parclo A) and exploring its operational and safety aspects. A microsimulation approach was followed to achieve these goals.The results show that the combined implementation of CVs and innovative intersections has reduced travel times, and delays by nearly 65.3%, and 29.2%, respectively. Additionally, the total number of conflicts, rear-end and lane change conflicts dropped by nearly 23.8%, 23.6% and 24.4%, respectively at full Continuous Flow Intersections and 100% MPRThe CGT-parclo A exhibited superior operational performance to a multitude of interchange designs in most tested cases. The CGT-parclo A reduced travel times, and delays as high as 55.7%, and 69.8%, respectively, compared to the parclo A and parclo progressA. The CGT-parclo A is the best form of parclo A interchanges in terms of reducing the likelihoods, severities and frequencies of crashes.
Author: Ahmed Abdelrahman
Publisher:
ISBN:
Category :
Languages : en
Pages : 54
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Book Description
The results showed that this alternative design could provide much benefits in terms of its operational performance. However, its poor safety performance could result in losses much higher than its benefits. The study concludes that DDIs could significantly decrease crash frequency, while DLTs could not provide safety benefits. However, DLTs might be more efficient for operational performance. It is recommended that appropriate safety countermeasures should be developed and implemented to enhance traffic safety at DLTs.
Author: Milan Zlatkovic
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 70
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Book Description
Innovative intersections and interchanges have proliferated in the State of Utah over the past several years. Continuous flow intersections and diverging diamond interchanges seem to offer improved traffic performance and safety due to their innovative designs. However, there are no clearly defined guidelines or methodologies for monitoring and measuring their performance. Yet, they have a broad impact on operations, safety, access, transit, land use, economic development, and pedestrian and non-motorized traffic. Due to these numerous and overlapping variables, there is a need to develop a standard methodology to further evaluate innovative designs with regards to different performance measures. The goal of this research is to develop a matrix of performance measures, which can be applied in practice to effectively evaluate innovative designs in terms of operations, safety, access, and multimodal accommodations. The study develops and tests an Excel-based tool for evaluation and comparison of different conventional and innovative designs. The tool is based on the existing methodologies and those currently being developed, and they provide analyses of these designs for different performance measures, such as operational, safety, transit and non-motorized user performance, access, and user costs. It can be used for planning, designing, and monitoring performance of innovative designs.
Author: Sara Bashir
Publisher:
ISBN:
Category : Intelligent control systems
Languages : en
Pages : 73
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Book Description
Connected Vehicle (CV) technologies have been a core component for the Intelligent Transportation Systems (ITS) due to their capability to support a variety of ITS applications and unite vehicles and infrastructure elements into a well-integrated transportation system. Connected vehicles refer to those that exchange information with each other and the infrastructure using Dedicated Short-Range communication (DSRC), known as Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), and Infrastructure-to-Vehicle (I2V) communications under Vehicular ad hoc Network (VANET). These communications improve safety, mobility, and productivity of transportation systems users. This research develops and tests CV-based algorithms for a Queue Warning (Q-WARN) application for heavy freight vehicles. The Q-WARN application uses CV technologies to allow vehicles within the queue to automatically broadcast their queued status information (e.g., rapid deceleration, disabled status, and lane location) to upstream vehicles as well as to infrastructure. The queue warnings are sent to oncoming vehicles to prevent rear-end or other secondary collisions. It can also provide drivers the appropriate warning to help them safely reduce their speed, make the decision of changing lanes, or use alternative routes through enhancing drivers’ situational awareness. This thesis focuses on Q-WARN applications for freight vehicles at signalized intersections that are located adjacent to I-80 in Wyoming, which are characterized by heavy truck traffic. Four locations in the state of Wyoming, characterized by heavy freight traffic, are selected as the test-case intersections. The algorithms developed are using the latitude/longitude (lat/lon) coordinates of freight CVs and intersections to form a communication link and share information. The tests were performed in VISSIM microsimulation with Econolite ASC/3 Software-in-the-Loop (SIL) traffic signal controller emulator. The scope of analyses is twofold. Firstly, from the traffic operation approach: queuing, total delays, and vehicle spacing were scrutinized at intersection. Secondly, from the traffic safety perspective, Time-to-Collision (TTC) and Post-Encroachment Time (PET), as two commonly used Surrogate Measures of Safety (SMoS), were assessed. Through analyses of simulation results, in-depth comparisons of these traffic flow and safety parameters at baseline (0%), 10%, 25%, 50%, 75%, and 100% CV Market Penetration Rates (MPRs) under the effect of Q-WARN application were performed. The simulation scenarios developed through communication protocol can be easily implemented in the field, since it uses universal technologies. The results from developed Q-WARN algorithms revealed that the application has a remarkable potential to improve traffic operation parameters at signalized intersections, as well as providing safety benefits, especially when applied to heavy freight vehicles. Findings indicated successful traffic operation performance of the developed Q-WARN application in reducing vehicle delays by an average of 2% to 5%, as well as increasing the spacing between vehicles up to 134%, which could be an indicator of safety benefits. The results depicted that as the CV-MPR increases, the means of both SMoS increases, leading to safety enhancement under the impact of Q-WARN application. The abundance of information obtained from CV vehicles can be used to further enhance different control algorithms and applications.
Author: Carroll J. Messer
Publisher: Transportation Research Board
ISBN: 9780309048682
Category : Technology & Engineering
Languages : en
Pages : 116
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Author: Nicholas J. Garber
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 116
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Book Description
The purpose of this study was to evaluate and compare the safety and operational characteristics of the single point urban interchange (SPUI) and the diamond interchange (DI) and develop guidelines that identify traffic and/or geometric conditions that favor one type of interchange over the other. State traffic engineers across the country were surveyed as to their experiences and opinions of the two types of interchanges in terms of operational performance and safety. Accident and operational data were also obtained for nine SPUIs and eight DIs. The interchange operations were studied using both field data and the computer simulation program TRAF-NETSIM. In addition, for each DI simulated, an SPUI counterpart was designed with the same geometric and traffic conditions for further comparison. No significant differences were found in the off-ramp, cross road, and overall interchange average delay. Ten volume scenarios were then developed and simulated for both interchanges at low- and high-volume conditions to analyze the effect of various traffic patterns on the relative operational performance of each interchange type. The accident data for the SPUIs and DIs were compared according to severity, collision type, and location on the interchange. No significant differences were found between the severity distribution and rates of the two interchange types. However, the proportion of on-ramp and off-ramp accidents was greater at the SPUI, and the proportion of accidents occurring in the center of the signalized intersection was greater at the DI. The proportion of angle accidents was greater at DIs than at SPUIs, whereas the proportions of rearend on-ramp, sideswipe, and fixed object accidents were greater at SPUIs. Vehicle conflicts at four interchanges in Virginia were also investigated and used along with the accident analysis results. The operational results, safety analyses, literature review, and survey of state engineers were used to develop guidelines to aid traffic engineers in the selection and design of the appropriate interchange type.
Author:
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 455
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Book Description
In order to alleviate saftey and congestion problems, several types of intersections have been suggested and implemented in some states. This report aims to evaluate the alternative intersections that have been implemented in other states and predict their effects when they are implemented in Florida.
Author: Ma'en Mohammad Ali Al-Omari
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Several unconventional intersection designs were proposed and implemented to enhance traffic safety and operation at intersections. The efficiency of these intersection designs was not sufficiently evaluated in the previous research because of the limited implementation of such designs. However, with the growing interest in the implementation of unconventional intersections by municipalities and transport agencies, it has become a need for a comprehensive evaluation of their safety and operational benefits. Therefore, this dissertation aims to evaluate the safety and operational aspects of unconventional intersection designs by employing different research approaches: crash analysis, microscopic simulation, and driving simulation. Firstly, this dissertation evaluated the effectiveness of median U-turn crossover-based intersections (median U-turn (MUT) and restricted crossing U-turn (RCUT) intersections), which have the least number of traffic conflicts among other unconventional intersection designs, in enhancing traffic safety by estimating crash modification factors (CMF) for their implementation. The results indicated that MUT and RCUT intersections are safer than the 4-leg conventional intersection. Secondly, A new innovative intersection design, which has been given the name "Shifting Movements" (SM) intersection, was introduced and proposed to replace the implementation of the RCUT intersection under moderate and heavy minor road traffic conditions. Evaluation of the operational benefits of this intersection design was performed in the microscopic simulation environment by assuming different traffic volume levels and left-turn proportions to represent the peak hour with moderate to high left-turn traffic volumes. The results demonstrated that the SM intersection design significantly outperforms conventional and RCUT intersections when they are subjected to high traffic volumes in terms of average control delay and throughput. Finally, A driving simulation experiment was conducted to evaluate the safety aspects of the SM intersection design. Several surrogate safety measures were adopted for the evaluation. The effectiveness of using infrastructure-to-vehicle (I2V) communication for mitigating the confusion at unconventional intersections has been also evaluated in this research. Findings indicated that RCUT and SM intersections have similar safety performance and crossing them is safer than crossing the 4-leg conventional intersection. It was found that using I2V communication is helpful in understanding unconventional movement patterns. This dissertation can be a solid reference for decision-makers regarding the implementation of unconventional intersection designs.
Author: Liteng Zha
Publisher:
ISBN:
Category : Highway communications
Languages : en
Pages : 62
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Crash-based safety evaluation is often hampered by randomness, lack of timeliness, and rarity of crash occurrences. Surrogate safety data are commonly used as an alternative to crash data; however, its current practice is still resource intensive and prone to human errors. The advent of connected vehicle technology allows vehicles to communicate with each other as well as infrastructure wirelessly. Through this platform, vehicle movements and signal status at the facilities can be automatically and continually monitored in real time. This study explores the viability of long-term safety performance evaluation at signalized intersection using connected vehicle technology. The development focuses on vehicle-to-infrastructure (V2I) communications which require one road-side equipment (RSE) and some level of on-board equipment to be successful. To accomplish the objective, the researchers defined useful safety measures and developed specific algorithms to derive them in real time from the V2I communication data sets. The safety measures were categorized into single-OBE measures and dual-OBE measure based on the number of the equipped vehicle needed to be monitored. We used vehicles trapped in dilemma zone as the single-OBE measure. The dual-OBE measures included rear-end and crossing conflicts. Different simulation scenarios were designed in VISSIM to test the effectiveness of the proposed framework, effect of market penetration rate as well as required observation period for effective implementation. The evaluation results indicated that the application can effectively detect changes in safety performance at full market penetration. It can detect a shift of crash pattern from rear-end crashes to right-angle crashes due to the shorted inter green interval at low traffic volume as well as the mitigation of this pattern during the medium-to-high traffic volume. The selected measures can also identify the increasing risk of rear-end and right-angle crashes after removing advance detectors at the major approaches. Sensitivity analysis from the 60 simulation hours' data showed that more than 40% and 60% penetration rate is likely to be required for a reliable detection in the low volume level and medium-to-high volume level, respectively. Increase of traffic volume activated the corresponding phases more frequently and may result in fewer safety measures being collected. Although losing the power of detection, single-OBE measure was demonstrated to be more reliable at lower penetration rate. Under low OBE market penetrations, observation period can be extended to compensate for small sample size. However, the required observation periods vary with the types of safety indicators being collected and the levels of OBE saturation. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152565
Author: National Research Council (U.S.). Transportation Research Board
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 184
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