TY - RPRT TI - North Carolina Department of Transportation Customer Survey Results 2017‐2018 AU - Findley, D.J. AU - Davis, J.C. AU - Akella, H. AU - Head, W. AU - Bert, S. A3 - North Carolina Department of Transportation’s Research & Development Unit DA - 2018/12// PY - 2018/12// M3 - Executive Summary – 2017-18 PB - North Carolina Department of Transportation’s Research & Development Unit ER - TY - RPRT TI - Evaluation of Railway Station Passenger Boarding Platform Gap Filler Solutions for North Carolina AU - Palmer, M. AU - Davis, J.C. AU - Cunningham, C. AU - Wright, W. AU - Chang, J. A3 - North Carolina Department of Transportation, Institute for Transportation Research & Education, North Carolina State University DA - 2018/11/30/ PY - 2018/11/30/ M1 - 2018-027 M3 - Final Project Report August 2017 to November 2018 PB - North Carolina Department of Transportation, Institute for Transportation Research & Education, North Carolina State University SN - 2018-027 ER - TY - RPRT TI - Research and Support for Automated Traffic Signal Performance Measures (ATSPM) and Signal System Retiming Prioritization AU - Davis, J.C. AU - Head, W. AU - Bert, S. A3 - North Carolina Department of Transportation DA - 2018/3// PY - 2018/3// PB - North Carolina Department of Transportation ER - TY - RPRT TI - Interim Analysis: Impact of North Carolina I-540 Westbound On-Ramp Signals AU - Davis, J.C. AU - Chase, T. AU - Aghdashi, B.S. AU - Head, W. AU - Jones, P. A3 - North Carolina Department of Transportation DA - 2018/5// PY - 2018/5// PB - North Carolina Department of Transportation ER - TY - RPRT TI - North Carolina: The State of Aviation AU - Findley, D.J. AU - Head, W. AU - Davis, J.C. A3 - North Carolina Division of Aviation DA - 2018/4// PY - 2018/4// PB - North Carolina Division of Aviation ER - TY - RPRT TI - The Great Smoky Mountains Railroad Economic Contribution of Railroad Operations and Visitors AU - Findley, D.J. AU - Head, W. AU - Gellert, C. AU - Bert, S. AU - Davis, J.C. A3 - Smoky Mountain Host of NC DA - 2018/3// PY - 2018/3// PB - Smoky Mountain Host of NC ER - TY - RPRT TI - An Analysis of North and South Carolina School Bus Crash Characteristics and Locations AU - Hart, K. AU - Palmer, M. AU - Davis, J.C. AU - Foley, B. AU - Konde, S. A3 - AAA Carolinas DA - 2018/// PY - 2018/// PB - AAA Carolinas ER - TY - RPRT TI - Evaluating the Economic Impact of Shared Use Paths in North Carolina AU - O'Brien, S. AU - Searcy, S. AU - Bert, S. AU - Jackson, K. AU - Carter, B. AU - Findley, D. AU - Hayes, M. AU - Bzomowski, S. AU - Duffy, M. AU - James, K. AU - Reyes, J. AU - Seagle, H. DA - 2018/2/28/ PY - 2018/2/28/ UR - https://itre.ncsu.edu/wp-content/uploads/2018/03/NCDOT-2015-44_SUP-Project_Final-Report_optimized.pdf ER - TY - RPRT TI - Peak Spreading Tool Implementation AU - Searcy, S. AU - Aghdashi, B. AU - Chase, T. AU - Huegy, J. DA - 2018/10/31/ PY - 2018/10/31/ UR - https://connect.ncdot.gov/projects/research/RNAProjDocs/NCDOT%202018-07%20Final%20Report%20with%20User's%20Manual_20180211.pdf ER - TY - JOUR TI - Evaluation of Virtual Controller Interface Device and Software-in-the-Loop Simulation T2 - Proceedings of the Institution of Civil Engineers - Transport AB - In current practice, hardware-in-the-loop simulation and software-in-the-loop simulation are two typical methods for traffic signal control research. The former uses a controller interface device (CID) to connect an actual traffic signal controller to micro-simulation software when conducting a simulation, whereas the latter uses software packages to take the roles of actual signal controllers. Using an actual signal controller can help to generate more reliable simulation results; however, the operational costs of CIDs limit the applicability of hardware-in-the-loop simulations. In this paper, a virtual controller interface device (VCID) is proposed to connect the actual signal controllers to simulation software. The proposed device communicates with the actual signal controller through the US national transportation communications for intelligent transportation systems protocol (NTCIP), which provides great operation flexibility, such as remote control, and reduces the operating costs compared with previous hardware-in-the-loop simulations. The simulation performance of the VCID is compared with software-in-the-loop simulations through a case study in this paper. It is found that the proposed device is able to provide accurate and reliable traffic simulation results: the relative difference with software-in-the-loop simulations is only 1·8%, but it requires significantly less effort and has a lower cost. DA - 2018/10/30/ PY - 2018/10/30/ DO - 10.1680/jtran.17.00149 UR - https://doi.org/10.1680/jtran.17.00149 KW - communications & control systems KW - design methods & aids KW - traffic engineering ER - TY - JOUR TI - Feasibility of Using a Constant Acceleration Rate for Freeway Entrance Ramp Acceleration Lane Length Design AU - Yang, Guangchuan AU - Wang, Zhongren AU - Xu, Hao AU - Tian, Zong T2 - Journal of Transportation Engineering, Part A: Systems AB - When estimating the required acceleration length of vehicles accelerating from a stopped position, a constant acceleration rate is sometimes assumed for the sake of simplicity. Nevertheless, to date there is no clear-cut evidence showing whether a constant acceleration rate is reasonable in providing appropriate acceleration lengths. In this paper, the estimation errors associated with the constant acceleration assumption were investigated. For each sample, a piecewise-constant acceleration model was used to figure out the vehicle’s speed versus location profile; accordingly, the constant acceleration rate was calculated. Using this constant acceleration rate, speeds at the predetermined locations were calculated and compared to the results that were generated by the piecewise-constant acceleration model. Based on the statistical analysis of 575 individual vehicle-accelerating trajectories, it was found that the constant acceleration model failed to reproduce the field-observed acceleration profile. Therefore, simply using a constant rate cannot accurately estimate the required acceleration lengths at various freeway design speed scenarios. This indicates that when adopting the constant acceleration assumption for each design speed scenario, it is necessary to use an appropriate acceleration rate that fits for this design speed. Finally, this paper revealed that normal acceleration rate ranges from 1.31 m/s2 (4.3 ft/s2) at 64 km/h (40 mph) to 1.8 m/s2 (5.9 ft/s2) at 32 km/h (20 mph). DA - 2018/3// PY - 2018/3// DO - 10.1061/jtepbs.0000122 VL - 144 IS - 3 SP - 06017001 KW - Acceleration length KW - Speed profile KW - Constant acceleration KW - Statistical test ER - TY - JOUR TI - Comparison of performance between Virtual Controller Interface Device and Controller Interface Device AU - Wang, Daobin AU - Tian, Zong AU - Yang, Guangchuan AU - Gholami, Ali T2 - IET Intelligent Transport Systems AB - A Controller Interface Device (CID) is a hardware that connects a signal controller to simulation software. Running traffic simulation with an actual controller is called hardware-in-the-loop simulation (HILS) and is an important tool for simulating the operations of traffic signals. In practice, it has been found that the existing traditional CIDs have some limitations, particularly when simulating multiple signals. In this regard, a Virtual CID (VCID) is proposed in this study. VCID can connect traffic signal controllers to a micro-simulation software through the National Transportation Communications for ITS Protocol (NTCIP). A case study is conducted that uses the same traffic networks to compare the performance of VCID to CID. Queue length, travel time and simulation stability are considered in the evaluation. Results show that VCID could provide accurate and reliable simulation results. In comparison to traditional CIDs, VCID has more advantages as it does not depend on any hardware device and is easy to operate. In addition, since the communications are transformed through Ethernet, thus providing a convenient learning and testing environment for those who do not own a physical signal control laboratory. Therefore, VCID will have a broader prospect for development than CID. DA - 2018/2/1/ PY - 2018/2/1/ DO - 10.1049/iet-its.2017.0050 VL - 12 IS - 1 SP - 22-30 KW - traffic engineering computing KW - control engineering computing KW - user interfaces KW - telecontrol KW - intelligent transportation systems KW - virtual controller interface device KW - virtual CID KW - VCID KW - traffic signal controllers KW - microsimulation software KW - National Transportation Communications KW - ITS Protocol KW - NTCIP KW - traffic networks KW - queue length KW - travel time KW - simulation stability KW - remote control KW - physical signal control laboratory ER - TY - JOUR TI - Modeling the Impacts of Traffic Flow Arrival Profiles on Ramp Metering Queues AU - Yang, Guangchuan AU - Yue, Rui AU - Tian, Zong AU - Xu, Hao T2 - Transportation Research Record: Journal of the Transportation Research Board AB - An adequate queue storage length is critical for a metered on-ramp to prevent ramp queue spillback to the upstream signalized intersection. Previous research on queue length estimation or queue storage length design at metered ramps has not taken into account the potential impact of various on-ramp traffic flow arrival profiles on ramp queue lengths. This paper depicts the traffic flow arrival profiles and queue generation processes at three different metered ramp categories. Based on a large number of microscopic simulation runs, it is found that, under a given demand-to-capacity scenario, the queue at a metered ramp with two on-ramp feeding movements is more likely to be cleared in a cycle than at a metered ramp with three on-ramp feeding movements. Also, the platoon dispersion effect significantly reduces the ramp queue length, and hence the queue storage needs at a metered ramp. In addition, this paper reveals that ramp queue length tends to increase linearly with upstream signal cycle length. The design of queue storage length for a metered on-ramp hence needs to fully consider the various ramp configurations and upstream signal timing settings. DA - 2018/6// PY - 2018/6// DO - 10.1177/0361198118782253 VL - 6 SP - 036119811878225 ER - TY - JOUR TI - Queue length estimation for a metered on-ramp using mesoscopic simulation AU - Yang, Guangchuan AU - Tian, Zong AU - Wang, Daobin AU - Xu, Hao T2 - Transportation Letters AB - This paper proposed an analytical method for queue length modeling at a metered on-ramp, and developed a mesoscopic simulation model for queue length estimation under various demand-to-capacity scenarios. Queue length data were collected at four representative ramp metering locations for model validation; results showed that the queue length modeling method could properly capture the realistic queue profile, and the estimated queue lengths were close to the field observations. It was found that for under-saturated scenarios, queue length showed an exponential increasing trend with demand-to-capacity ratio; while for over-saturated scenarios, the queue length tended to increase linearly with demand-to-capacity ratio. Simulation results indicated that for under-saturated conditions, the required queue storage length was approximately 5.7 percent of on-ramp demand when demand was less than 500 vphpl, or 3.9 percent when demand was between 500 and 900 vphpl. DA - 2018/5// PY - 2018/5// DO - 10.1080/19427867.2018.1477491 VL - 5 SP - 1-10 KW - Ramp metering KW - queue length modeling KW - mesoscopic simulation KW - demand-to-capacity ratio KW - queue storage length ER - TY - CONF TI - Replication of Annual Average Daily Bicyclists Estimation Methodology Based on North Carolina Count Data AU - Searcy, S. C2 - 2018/// C3 - Proceedings of the 97th Annual Meeting of the Transportation Research Board DA - 2018/// UR - https://trid.trb.org/View/1495512 ER - TY - RPRT TI - Additional Analysis of National Child Restraint Use Special Study: Child Restraint Misuse AU - Raymond, P. AU - Searcy, S. AU - Findley, D. A3 - National Highway Traffic Safety Administration DA - 2018/7// PY - 2018/7// M3 - Report No. DOT HS 812 527). PB - National Highway Traffic Safety Administration UR - https://rosap.ntl.bts.gov/view/dot/38686 ER - TY - RPRT TI - Additional Analysis of National Child Restraint Use Special Study: Characteristics Of Those Not Restrained AU - Raymond, P. AU - Searcy, S. AU - Miller, S. AU - Redden, C. A3 - National Highway Traffic Safety Administration DA - 2018/3// PY - 2018/3// M3 - (Report No. DOT HS 812 477). PB - National Highway Traffic Safety Administration UR - https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/documents/812477_additional-analysis-national-child-restraint-use-special-study-characteristics-those-not-restrained-research-note-tsf.pdf ER - TY - JOUR TI - Distributed optimization and coordination algorithms for dynamic speed optimization of connected and autonomous vehicles in urban street networks AU - Tajalli, Mehrdad AU - Hajbabaie, Ali T2 - Transportation research part C: emerging technologies AB - Dynamic speed harmonization has shown great potential to smoothen the flow of traffic and reduce travel time in urban street networks. The existing methods, while providing great insights, are neither scalable nor real-time. This paper develops Distributed Optimization and Coordination Algorithms (DOCA) for dynamic speed optimization of connected and autonomous vehicles in urban street networks to address this gap. DOCA decomposes the nonlinear network-level speed optimization problem into several sub-network-level nonlinear problems thus, it significantly reduces the problem complexity and ensures scalability and real-time runtime constraints. DOCA creates effective coordination in decision making between each two sub-network-level nonlinear problems to push solutions towards optimality and guarantee attaining near-optimal solutions. DOCA is incorporated into a model predictive control approach to allow for additional consensus between sub-network-level problems and reduce the computational complexity further. We applied the proposed solution technique to a real-world network in downtown Springfield, Illinois and observed that it was scalable and real-time while finding solutions that were at most 2.7% different from the optimal solution of the problem. We found significant improvements in network operations and considerable reductions in speed variance as a result of dynamic speed harmonization. DA - 2018/// PY - 2018/// DO - 10.1016/j.trc.2018.07.012 VL - 95 SP - 497-515 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85051259651&partnerID=MN8TOARS ER - TY - JOUR TI - Dynamic speed harmonization in connected urban street networks AU - Tajalli, Mehrdad AU - Hajbabaie, Ali T2 - Computer-Aided Civil and Infrastructure Engineering AB - Abstract Connected vehicle technology, the Internet of Things, and other advanced communication technologies create possibilities to facilitate the movement of vehicles through transportation networks and reduce their travel time. Harmonizing the speed of vehicles in different network links not only yields a more efficient network capacity utilization, but also regulates the movement of vehicles to achieve a “smoother” flow of traffic. This study develops a mathematical nonlinear formulation for dynamic speed harmonization in urban street networks aiming at improving traffic operations. We have converted the nonlinear problem into a linear program utilizing the fundamental flow–density relationship and developed a model predictive control approach to account for stochastic changes in traffic demand and further improve the efficiency of the developed solution algorithm. Results showed that the algorithm efficiently found dynamic optimal advisory speeds on various network links, and speed harmonization significantly reduced the travel time (up to 5.4%), speed variance (19.8%–29.4%), and the number of stops (8.3%–18.5%), while increasing the average speed (up to 5.9%) and the number of completed trips (up to 4%) in our case study network under all tested demand patterns. DA - 2018/// PY - 2018/// DO - 10.1111/mice.12360 VL - 33 IS - 6 SP - 510-523 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85043677737&partnerID=MN8TOARS ER - TY - JOUR TI - Dynamic traffic metering in urban street networks: Formulation and solution algorithm AU - Mohebifard, Rasool AU - Hajbabaie, Ali T2 - Transportation research part C: emerging technologies AB - Traffic metering offers great potential to reduce congestion and enhance network performance in oversaturated urban street networks. This paper presents an optimization program for dynamic traffic metering in urban street networks based on the Cell Transmission Model (CTM). We have formulated the problem as a Mixed-Integer Linear Program (MILP) capable of metering traffic at network gates with given signal timing parameters at signalized intersections. Due to the complexities of the MILP model, we have developed a novel and efficient solution approach that solves the problem by converting the MILP to a linear program and several CTM simulation runs. The solution algorithm is applied to two case studies under different conditions. The proposed solution technique finds solutions that have a maximum gap of 1% of the true optimal solution and guarantee the maximum throughput by keeping some vehicles at network gates and only allowing enough vehicles to enter the network to prevent gridlocks. This is confirmed by comparing the case studies with and without traffic metering. The results in an adapted real-world case study network show that traffic metering can increase network throughput by 4.9–38.9% and enhance network performance. DA - 2018/// PY - 2018/// DO - 10.1016/j.trc.2018.04.027 VL - 93 SP - 161-178 UR - https://doi.org/10.1016/j.trc.2018.04.027 KW - Traffic metering KW - Perimeter control KW - Mixed integer linear programming KW - Optimization KW - Cell transmission model KW - Benders decomposition KW - Urban street networks ER - TY - JOUR TI - Development of a signal-head-free intersection control logic in a fully connected and autonomous vehicle environment AU - Mirheli, Amir AU - Hajibabai, Leila AU - Hajbabaie, Ali T2 - Transportation Research Part C: Emerging Technologies AB - Establishment of effective cooperation between vehicles and transportation infrastructure improves travel reliability in urban transportation networks. Lack of collaboration, however, exacerbates congestion due mainly to frequent stops at signalized intersections. It is beneficial to develop a control logic that collects basic safety message from approaching connected and autonomous vehicles and guarantees efficient intersection operations with safe and incident free vehicle maneuvers. In this paper, a signal-head-free intersection control logic is formulated into a dynamic programming model that aims to maximize the intersection throughput. A stochastic look-ahead technique is proposed based on Monte Carlo tree search algorithm to determine the near-optimal actions (i.e., acceleration rates) over time to prevent movement conflicts. Our numerical results confirm that the proposed technique can solve the problem efficiently and addresses the consequences of existing traffic signals. The proposed approach, while completely avoids incidents at intersections, significantly reduces travel time (ranging between 59.4% and 83.7% when compared to fixed-time and fully-actuated control strategies) at intersections under various demand patterns. DA - 2018/// PY - 2018/// DO - 10.1016/j.trc.2018.04.026 VL - 92 SP - 412-425 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85047272483&partnerID=MN8TOARS KW - Control logic KW - Autonomous intersection control KW - Monte Carlo tree search KW - Look-ahead model KW - Connected and autonomous vehicles KW - Dynamic programming ER - TY - JOUR TI - Characteristics and Temporal Stability of Recurring Bottlenecks AU - Ahmed, Ishtiak AU - Rouphail, Nagui M. AU - Tanvir, Shams T2 - TRANSPORTATION RESEARCH RECORD AB - This study applies and updates a method which identifies and quantifies the extent of traffic congestion from recurring freeway bottlenecks. Additionally, the spatiotemporal stability of bottlenecks over an extended period was tested. Over time congestion at bottlenecks may increase, may decrease, or may migrate to other nearby locations. Analysis of stability is important since prioritizing and applying treatments at bottlenecks is a multiyear process. In addition, a robust method for selecting sensitivity based parameters to identify and quantify bottleneck effects is presented. Subsequently, a systematic framework is developed for tracking and archiving the spatiotemporal changes in the recurring bottlenecks. The proposed method is demonstrated on a case study on Interstate 40 in North Carolina using three years of probe data. A congestion speed ratio detection threshold of 0.7 and a probability of activation threshold of 33% for the study area were determined from a sensitivity test to ascertain their recurrence. The method identified 13 bottlenecks with their impacts ranging from 35 to 3,278 mi-hours of congestion per year. Eight bottlenecks either newly emerged or had their queues merged or shifted between successive years. Even spatially stable bottlenecks had significant variation in their activation frequency and queue length. Exploration of the changes in bottleneck severity and locations revealed the influence of a long-term work zone in the area and the effect of the rapid growth in traffic demand. Local agencies can use this method to shortlist recurring bottlenecks and track changes to plan mitigation strategies. DA - 2018/12// PY - 2018/12// DO - 10.1177/0361198118798991 VL - 2672 IS - 42 SP - 235-246 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85060989618&partnerID=MN8TOARS ER - TY - JOUR TI - Validation and Calibration of Freeway Reliability Methodology in the Highway Capacity Manual: Method and Case Studies AU - Karmakar, Nabaruna AU - Aghdashi, Seyedbehzad AU - Rouphail, Nagui M. AU - Williams, Billy M. T2 - TRANSPORTATION RESEARCH RECORD AB - Traffic congestion costs drivers an average of $1,200 a year in wasted fuel and time, with most travelers becoming less tolerant of unexpected delays. Substantial efforts have been made to account for the impact of non-recurring sources of congestion on travel time reliability. The 6 th edition of the Highway Capacity Manual (HCM) provides a structured guidance on a step-by-step analysis to estimate reliability performance measures on freeway facilities. However, practical implementation of these methods poses its own challenges. Performing these analyses requires assimilation of data scattered in different platforms, and this assimilation is complicated further by the fact that data and data platforms differ from state to state. This paper focuses on practical calibration and validation methods of the core and reliability analyses described in the HCM. The main objective is to provide HCM users with guidance on collecting data for freeway reliability analysis as well as validating the reliability performance measures predictions of the HCM methodology. A real-world case study on three routes on Interstate 40 in the Raleigh-Durham area in North Carolina is used to describe the steps required for conducting this analysis. The travel time index (TTI) distribution, reported by the HCM models, was found to match those from probe-based travel time data closely up to the 80 th percentile values. However, because of a mismatch between the actual and HCM estimated incident allocation patterns both spatially and temporally, and the fact that traffic demands in the HCM methods are by default insensitive to the occurrence of major incidents, the HCM approach tended to generate larger travel time values in the upper regions of the travel time distribution. DA - 2018/12// PY - 2018/12// DO - 10.1177/0361198118798723 VL - 2672 IS - 15 SP - 93-104 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85060939515&partnerID=MN8TOARS ER - TY - JOUR TI - Application of a Discontinuous Form of Macroscopic Gazis-Herman-Rothery Model to Steady-State Freeway Traffic Stream Observations AU - Ahmed, Ishtiak AU - Williams, Billy M. AU - Samandar, M. Shoaib T2 - TRANSPORTATION RESEARCH RECORD AB - In this study, a two-regime, steady-state, traffic stream model is developed by applying the macroscopic Gazis–Herman–Rothery model to fixed sensor data on freeways. The uncongested and congested regimes are modeled discontinuously with an overlap range defined in terms of density. The overlap is important as various phenomena related to the change in traffic state can be modeled by introducing this overlap. Two empirical tools for removing non-stationary, mixed-state, and erroneous observations are applied at different stages of the model development process. Three constraints justified by the Highway Capacity Manual (HCM) were applied to fit the model so that the fitted parameters have reasonable and physically interpretable values. The proposed model is applied to one year of data (2013) obtained from fixed sensors located at five freeway basic segments near Raleigh, North Carolina. The resulting fundamental diagrams show that the fitted models reasonably represent the steady-state observations. Two forms of the freeway flow model described in the HCM were applied to the same observations to provide a continuous model comparison. Two statistical performance measures, mean squared error of flow rate and Bayesian Information Criterion, verify that the proposed model is preferable to the HCM models both in terms of fit alone and when considering the tradeoff between fit and model complexity. It is expected that the proposed discontinuous steady-state model will be useful to researchers and practitioners to study various site-specific freeway traffic stream characteristics. DA - 2018/12// PY - 2018/12// DO - 10.1177/0361198118799166 VL - 2672 IS - 20 SP - 51-62 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85060947455&partnerID=MN8TOARS ER - TY - JOUR TI - Weigh Station Impact on Truck Travel Time Reliability: Results and Findings from a Field Study and a Simulation Experiment AU - Samandar, M. Shoaib AU - Williams, Billy M. AU - Ahmed, Ishtiak T2 - TRANSPORTATION RESEARCH RECORD AB - Weigh stations are necessary for safeguarding highway infrastructure by enforcing truck weight limits. However, mandating all trucks to stop at all weigh stations decreases travel time reliability. This decrease in travel time reliability adversely impacts the productivity of the trucking industry and to a lesser degree impacts personal travel reliability as well. This study, conducted at the Lumberton weigh station on Interstate 95 in North Carolina, quantifies the impact of weigh stations on truck travel time reliability. Truck travel times were observed over periods of weigh station operation and weigh station closure. Comparison of these two states sheds light on the variability in travel time caused by weigh station operation. Results show that when the weigh station is operational, truck travel time reliability degrades significantly. VISSIM microsimulation software was used to quantify the expected impact of weigh in motion (WIM) on truck travel time reliability assuming different scenarios of WIM truck bypass. The model results indicate that WIM technology does increase travel time reliability and provides benefits to both trucking companies and enforcement agencies. It was also found that increases in the proportion of WIM bypass result in increases in route travel time reliability. However, this simulation model improvement was not uniform, with the highest marginal improvement occurring in the 30%–40% WIM bypass range. DA - 2018/12// PY - 2018/12// DO - 10.1177/0361198118791667 VL - 2672 IS - 9 SP - 120-129 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85052711188&partnerID=MN8TOARS ER - TY - JOUR TI - Reliability Assessment Tool: Development and Prototype Testing AU - List, George F. AU - Rouphail, Nagui AU - Smith, Russell AU - Williams, Billy T2 - TRANSPORTATION RESEARCH RECORD AB - This paper presents a monitoring system that was developed to assess travel time reliability for observed operating conditions by utilizing traffic stream and non-transportation related data. A prototype was created for an interstate highway route in the Research Triangle region of North Carolina. It describes how the input datasets were obtained, the required data fusion procedures, how the data were analyzed to create the monitoring system outputs, and relevant insights obtained from the reliability monitoring system prototype. DA - 2018/12// PY - 2018/12// DO - 10.1177/0361198118798296 VL - 2672 IS - 14 SP - 29-38 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85060926457&partnerID=MN8TOARS ER - TY - JOUR TI - Effect of Light Duty Vehicle Performance on a Driving Style Metric AU - Tanvir, Shams AU - Frey, H. Christopher AU - Rouphail, Nagui M. T2 - TRANSPORTATION RESEARCH RECORD AB - Eco-driving involves alterations to driving style to improve energy efficiency. The observed driving style reflects the combined effects of roadway, traffic, driver, and vehicle performance. Although the effect of roadway and traffic characteristics can be inferred from microscale driving activity data, the effect of vehicle performance on driving style is not properly understood. This paper addresses two questions: (1) how different is an individual driver’s driving style when operating vehicles with differences in performance?; and (2) how dissimilar are the driving styles of different drivers when operating vehicles that have similar performance? To answer these questions, we have gathered microscale vehicle activity measurements from 17 controlled real-world driving schedules and two years of naturalistic driving data from five drivers. We also developed a metric for driving style termed “envelope deviation,” which is a distribution of gaps between microscale activity (1 Hz) and fleet average envelope. We found that there is significant inter-driver heterogeneity in driving styles when controlling for vehicle performance. However, no significant inter-vehicle heterogeneity was present in driving styles while controlling for the driver. Findings from this study imply that the choice of vehicle does not significantly alter the natural driving style of a driver. DA - 2018/12// PY - 2018/12// DO - 10.1177/0361198118796070 VL - 2672 IS - 25 SP - 67-78 SN - 2169-4052 ER - TY - RPRT TI - A National Model for Predicting Life Cycle Costs and Benefits of Intersection Control Alternatives AU - Findley, D.J. AU - Aghdashi, B. AU - Davis, J. AU - Cunningham, C. A3 - University of Maryland. National Transportation Center DA - 2018/3/30/ PY - 2018/3/30/ M1 - NTC2016-MU-R-03 M3 - Report PB - University of Maryland. National Transportation Center SN - NTC2016-MU-R-03 UR - http://ntc.umd.edu/node/169 ER - TY - JOUR TI - Evaluation of wait times and queue lengths at ferry terminals AU - Findley, Daniel J. AU - Anderson, Tracy J. AU - Bert, Steven A. AU - Nye, Timothy AU - Letchworth, Will T2 - RESEARCH IN TRANSPORTATION ECONOMICS AB - Transportation systems often require travelers to wait for service. Observational data from a wait-time study at ferry terminals demonstrate that the amount of time a vehicle waits to board a ferry is highly dependent on that vehicle's position in line. Queue psychology suggests that unexplained waits, uncertainty, and anxiety make wait times for individuals seem longer. Thus, the vehicle position and wait time relationship can be used to equip ferry service providers with the knowledge to inform and pacify passengers waiting to board a ferry. DA - 2018/11// PY - 2018/11// DO - 10.1016/j.retrec.2018.06.009 VL - 71 SP - 27-33 SN - 1875-7979 UR - https://doi.org/10.1016/j.retrec.2018.06.009 KW - Ferry KW - Tourism KW - Travel KW - Waiting times KW - Queuing time KW - Time perception KW - Wait perception KW - Queue length KW - Queuing KW - Travel time KW - Ferry terminal KW - Wait anxiety KW - Queue anxiety KW - Information KW - Customer information KW - Travel information ER - TY - JOUR TI - Closure to "Comparison of Three Retaining Wall Condition Assessment Rating Systems" by Mohammed A. Gabr, William Rasdorf, Daniel J. Findley, Cedrick J. Butler, and Steven A. Bert AU - Gabr, Mohammed A. AU - Rasdorf, William AU - Findley, Daniel J. AU - Butler, Cedrick J. AU - Bert, Steven A. T2 - JOURNAL OF INFRASTRUCTURE SYSTEMS DA - 2018/12// PY - 2018/12// DO - 10.1061/(ASCE)IS.1943-555X.0000447 VL - 24 IS - 4 SP - SN - 1943-555X ER - TY - JOUR TI - Simulation of Work Zones with Lane Closures in Proximity of Freeway Interchanges AU - Yeom, Chunho AU - Rasdorf, William AU - Rouphail, Nagui AU - Schroeder, Bastian T2 - IEEE INTELLIGENT TRANSPORTATION SYSTEMS MAGAZINE AB - The paper provides methodologies for microscopic simulation modelling of freeway work zones with lane closures in the proximity of interchanges. In addition, the research presents simulation results using calibrated modelling parameters to determine the capacity available for mainline flow under various operating conditions. The results will help researchers or practitioners with designing and studying freeway work zone sites under various lane configurations using better estimates of delays and queue sizes in the proximity of interchanges. Additionally, a 2 to 1 on-ramp merge condition was explored to predict the merge ratios under both demand and service flow conditions. The paper illustrates how ramp demand affects the share of segment capacity available to mainline traffic to reveal strategies for controlling this demand (via ramp metering for example) in order to maintain a prescribed freeway capacity through the work zone. The overall study result indicates the degree to which the presence of a work zone with lane closures decreases the proportion of mainline flow and shows the degree to which differences in work zone lane configurations affect merge and weave scenarios. DA - 2018/// PY - 2018/// DO - 10.1109/MITS.2018.2842027 VL - 10 IS - 3 SP - 184-195 SN - 1941-1197 ER - TY - JOUR TI - Real-Time Prediction of Seasonal Heteroscedasticity in Vehicular Traffic Flow Series AU - Huang, Wei AU - Jia, Wenwen AU - Guo, Jianhua AU - Williams, Billy AU - Shi, Guogang AU - Wei, Yun AU - Cao, Jinde T2 - IEEE Transactions on Intelligent Transportation Systems AB - Over the past decade, traffic heteroscedasticity has been investigated with the primary purpose of generating prediction intervals around point forecasts constructed usually by short-term traffic condition level forecasting models. However, despite considerable advancements, complete traffic patterns, in particular the seasonal effect, have not been adequately handled. Recently, an offline seasonal adjustment factor plus GARCH model was proposed in Shi et al. 2014 to model the seasonal heteroscedasticity in traffic flow series. However, this offline model cannot meet the real-time processing requirement proposed by real-world transportation management and control applications. Therefore, an online seasonal adjustment factors plus adaptive Kalman filter (OSAF+AKF) approach is proposed in this paper to predict in real time the seasonal heteroscedasticity in traffic flow series. In this approach, OSAF and AKF are combined within a cascading framework, and four types of online seasonal adjustment factors are developed considering the seasonal patterns in traffic flow series. Empirical results using real-world station-by-station traffic flow series showed that the proposed approach can generate workable prediction intervals in real time, indicating the acceptability of the proposed approach. In addition, compared with the offline model, the proposed online approach showed improved adaptability when traffic is highly volatile. These findings are important for developing real-time intelligent transportation system applications. DA - 2018/// PY - 2018/// DO - 10.1109/TITS.2017.2774289 VL - 19 IS - 10 SP - 3170–3180 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85038392558&partnerID=MN8TOARS ER - TY - JOUR TI - Delivery of Automated External Defibrillators (AED) by Drones: Implications for Emergency Cardiac Care AU - Zegre-Hemsey, Jessica K. AU - Bogle, Brittany AU - Cunningham, Christopher J. AU - Snyder, Kyle AU - Rosamond, Wayne T2 - CURRENT CARDIOVASCULAR RISK REPORTS AB - Out-of-hospital cardiac arrest (OHCA) remains a significant health problem in the USA and only 8.6% of victims survive with good neurological function, despite advances in emergency cardiac care. The likelihood of OHCA survival decreases by 10% for every minute without resuscitation. Automatic external defibrillators (AEDs) have the potential to save lives yet public access defibrillators are underutilized (< 2% of the time) because they are difficult to locate and rarely available in homes or residential areas, where the majority (70%) of OHCA occur. Even when AEDs are within close proximity (within 100 m), they are not used 40% of the time. Unmanned aerial vehicles, or drones, have the potential to deliver AEDs to a bystander and augment emergency medical service (EMS) care. We review the use of drones in medicine, what is currently known, and clinical implications for advancing emergency cardiac care. DA - 2018/11// PY - 2018/11// DO - 10.1007/s12170-018-0589-2 VL - 12 IS - 11 SP - SN - 1932-9563 KW - Sudden cardiac arrest KW - Automatic external defibrillation KW - Public access defibrillation KW - Unmanned aerial vehicles KW - Drones ER - TY - JOUR TI - Data-driven approach for identifying spatiotemporally recurrent bottlenecks AU - Song, Tai-Jin AU - Williams, Billy M. AU - Rouphail, Nagui M. T2 - IET INTELLIGENT TRANSPORT SYSTEMS AB - Identification of recurrent bottlenecks is an effective way to hone an appropriate investment in current facilities to relieve congestion. Furthermore, it would enable the ranking or prioritisation of bottlenecks since bottleneck removal and its associated impact alleviation are hampered by limited sources. It is imperative that transportation jurisdiction understand and identify the basis for ranking bottlenecks by exploring: how often they are active; how long it takes the congestion to disappear; and how many miles of road are affected. Previous bottleneck identification schemes have focused on identifying congestion with little attention to distinguishing the recurrent level at the same ‘bottleneck’ location. In contrast to traditional schemes, a data-driven approach for identifying recurrent bottlenecks is introduced, using probe vehicle speed reports. The historical spatiotemporal characteristics of bottlenecks are investigated through a comprehensive analysis of 2253 miles of all state-wide interstates in North Carolina. Using the characteristics determined the recurrent bottleneck locations with a historical time span of bottleneck activation are revealed and tested. The findings of the proposed identification schemes generate critical information in order to quantify and diagnose a bottleneck and its associated impact area. DA - 2018/10// PY - 2018/10// DO - 10.1049/iet-its.2017.0284 VL - 12 IS - 8 SP - 756-764 SN - 1751-9578 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85053217294&partnerID=MN8TOARS ER - TY - JOUR TI - Effect of residential proximity on university student trip frequency by mode AU - Searcy, Sarah E. AU - Findley, Daniel J. AU - Huegy, Joseph B. AU - Ingram, Mei AU - Mei, Bing AU - Bhadury, Joyendu AU - Wang, Chao T2 - TRAVEL BEHAVIOUR AND SOCIETY AB - • A fractional polynomial regression was used to model university student trips. • Non-motorized trips comprise the majority of trips at short distances from campus. • Automobile and transit trips comprise the majority of trips at longer distances. • Services can be put close to students’ residences to maximize non-motorized trips. DA - 2018/7// PY - 2018/7// DO - 10.1016/j.tbs.2017.12.007 VL - 12 SP - 115-121 SN - 2214-3688 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85039937263&partnerID=MN8TOARS ER - TY - JOUR TI - Comparison of Three Retaining Wall Condition Assessment Rating Systems AU - Gabr, Mohammed A. AU - Rasdorf, William AU - Findley, Daniel J. AU - Butler, Cedrick J. AU - Bert, Steven A. T2 - JOURNAL OF INFRASTRUCTURE SYSTEMS AB - In general, the nature of permanent earth retaining structures (ERSs) in highway engineering is well suited to the concept of asset management as a valuable tool for operational efficiency and cost control. Earth retaining structure failures can be detrimental to the roadway and the surroundings, and may pose potential hazards to the safety of the public. Work in this paper utilized field survey results from 11 ERSs to illustrate the disadvantages of using a numerical rating system that relies on a single average number, and the applicability of the alternative system presented herein. The ERSs evaluated include mechanically stabilized earth (MSE), soil nail, anchored, gravity, and cantilever earth retaining wall types. Results indicated that the use of a single-value numerical rating can mask deficiencies in ERS elements that are critical to the stability and function of the ERS system. In addition, the identification of specific elements in distress is not apparent when using such an approach. An alternative two-part rating system provides a summary rating that articulates both the condition of the ERS and identifies potential problems with specific ERS elements. As transportation agencies attempt to align with Moving Ahead for Progress in the 21st Century Act (MAP-21), a two-part condition rating system is recommended to better execute an ERS asset management program and integrate it into a systemwide plan. DA - 2018/3// PY - 2018/3// DO - 10.1061/(asce)is.1943-555x.0000403 VL - 24 IS - 1 SP - SN - 1943-555X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85032731264&partnerID=MN8TOARS KW - Earth retaining structures KW - Infrastructure asset management KW - Retaining wall inventory KW - Asset inventory KW - Data collection KW - Rating system KW - Condition assessment ER -