@article{hasnat_bardaka_samandar_2023, title={Differential impacts of autonomous and connected-autonomous vehicles on household residential location}, volume={32}, ISSN={["2214-3688"]}, DOI={10.1016/j.tbs.2023.02.007}, abstractNote={High market penetration of autonomous vehicles (AVs) and connected-autonomous vehicles (CAVs) is expected to impact transportation network performance, which is an important determinant of residential location decisions, especially for households who commute to work by personal vehicle. This study examines and compares the impacts of privately owned AVs and CAVs on the location and commute characteristics as well as the spatial distribution of households within the Triangle Region in North Carolina. A Mixed Multinomial Logit model is developed using recent household survey data to capture household preferences. In addition, the region’s travel demand model, the Triangle Regional Model, is used to predict the network-level impacts of AV and CAV adoption, and cluster analysis is conducted to explore how network performance changes vary with transportation demand and supply zone characteristics at a local and regional level. Residential location patterns are predicted for a number of AV and CAV scenarios for the year 2045 using the outputs of the econometric analysis and the Triangle Regional Model. We find that extensive adoption of private CAVs improves network conditions and encourages households to live farther from work, leading up to a 5.6% increase in suburban and rural households that commute to work by personal vehicles. A high market share of AVs is associated with deteriorated transportation network performance and up to a 2.8% increase in urban households. Results vary by market penetration rate of each technology, mix of AVs, CAVs, and human driven vehicles in the traffic stream, and fuel type (conventional-fuel versus electric vehicles).}, journal={TRAVEL BEHAVIOUR AND SOCIETY}, author={Hasnat, Md Mehedi and Bardaka, Eleni and Samandar, M. Shoaib}, year={2023}, month={Jul} }
 @article{samandar_chun_yang_chase_rouphail_list_2022, title={Capitalizing on Drone Videos to Calibrate Simulation Models for Signalized Intersections and Roundabouts}, volume={6}, ISSN={["2169-4052"]}, DOI={10.1177/03611981221096120}, abstractNote={Simulation is an indispensable tool for the assessment of highway-related capital investments and operational changes. Model calibration, a challenging task in any simulation study, is a crucial step. The model’s robustness, accuracy, and quality are directly dependent on it. Many parameters exist, and field observations are often lacking to aid in their correct specification. Recently, videos from drones have created a uniquely powerful way to aid this process. Observations of the inputs (demand), outputs (vehicles processed), processing rates (e.g., saturation flow rates), and performance results (times in system, queue dynamics, and delays) are all available simultaneously. For signalized intersections, only the signal timing events are missing, and those data can be obtained from signal timing logs. This paper illustrates how modeling teams can use drone data to calibrate model parameters pertaining to intersection operation. It shows how saturation flow rates can be adjusted for signalized intersections so that queue dynamics and delays can be matched. For roundabouts, it illustrates how critical gaps and move-up times can be adjusted to match field observations of performance. Three real-world settings with associated drone data are used as case study examples.}, journal={TRANSPORTATION RESEARCH RECORD}, author={Samandar, M. Shoaib and Chun, Gyounghoon and Yang, Guangchuan and Chase, Thomas and Rouphail, Nagui M. and List, George F.}, year={2022}, month={Jun} }
 @article{ahmed_williams_samandar_chun_2022, title={Investigating the relationship between freeway rear-end crash rates and macroscopically modeled reaction time}, volume={18}, ISSN={["2324-9943"]}, url={https://doi.org/10.1080/23249935.2021.1914769}, DOI={10.1080/23249935.2021.1914769}, abstractNote={This study tests the hypothesis that an analytically estimated driver reaction time required for asymptotic stability, based on the macroscopic Gazis-Herman-Rothery (GHR) model, serves as an indicator of the impact of traffic oscillations on rear-end crashes. If separate GHR models are fit discontinuously for different traffic regimes, the local drop in required reaction time between these regimes can also be estimated. This study evaluates the relationship between rear-end crash rates and that drop in required reaction time. Traffic data from 28 sensors were used to fit the GHR model. Rear-end crash rates, estimated from four years of crash data, exhibited a positive correlation with the drop in required reaction time at the congested regime’s density-breakpoint. A linear relationship provided the best fit. These results motivate follow-on research to incorporate macroscopically derived reaction time in road-safety planning. More generally, the study demonstrates a useful application of a discontinuous macroscopic traffic model.}, number={3}, journal={TRANSPORTMETRICA A-TRANSPORT SCIENCE}, publisher={Informa UK Limited}, author={Ahmed, Ishtiak and Williams, Billy M. and Samandar, M. Shoaib and Chun, Gyounghoon}, year={2022}, month={Dec}, pages={1001–1024} }
 @article{hasnat_bardaka_samandar_rouphail_list_williams_2021, title={Impacts of Private Autonomous and Connected Vehicles on Transportation Network Demand in the Triangle Region, North Carolina}, volume={147}, ISSN={["1943-5444"]}, url={https://doi.org/10.1061/(ASCE)UP.1943-5444.0000649}, DOI={10.1061/(ASCE)UP.1943-5444.0000649}, abstractNote={Abstract Autonomous and connected vehicle technologies have the potential to bring profound changes in travel behavior and transportation network performance with moderate to significant market pen...}, number={1}, journal={JOURNAL OF URBAN PLANNING AND DEVELOPMENT}, publisher={American Society of Civil Engineers (ASCE)}, author={Hasnat, Md. Mehedi and Bardaka, Eleni and Samandar, M. Shoaib and Rouphail, Nagui and List, George and Williams, Billy}, year={2021}, month={Mar} }
 @article{dubljevic_list_milojevich_ajmeri_bauer_singh_bardaka_birkland_edwards_mayer_et al._2021, title={Toward a rational and ethical sociotechnical system of autonomous vehicles: A novel application of multi-criteria decision analysis}, volume={16}, ISSN={1932-6203}, url={http://dx.doi.org/10.1371/journal.pone.0256224}, DOI={10.1371/journal.pone.0256224}, abstractNote={The impacts of autonomous vehicles (AV) are widely anticipated to be socially, economically, and ethically significant. A reliable assessment of the harms and benefits of their large-scale deployment requires a multi-disciplinary approach. To that end, we employed Multi-Criteria Decision Analysis to make such an assessment. We obtained opinions from 19 disciplinary experts to assess the significance of 13 potential harms and eight potential benefits that might arise under four deployments schemes. Specifically, we considered: (1) the status quo, i.e., no AVs are deployed; (2) unfettered assimilation, i.e., no regulatory control would be exercised and commercial entities would “push” the development and deployment; (3) regulated introduction, i.e., regulatory control would be applied and either private individuals or commercial fleet operators could own the AVs; and (4) fleets only, i.e., regulatory control would be applied and only commercial fleet operators could own the AVs. Our results suggest that two of these scenarios, (3) and (4), namely regulated privately-owned introduction or fleet ownership or autonomous vehicles would be less likely to cause harm than either the status quo or the unfettered options.}, number={8}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Dubljevic, Veljko and List, George and Milojevich, Jovan and Ajmeri, Nirav and Bauer, William A. and Singh, Munindar P. and Bardaka, Eleni and Birkland, Thomas A. and Edwards, Charles H. W. and Mayer, Roger C. and et al.}, editor={Yuan, QuanEditor}, year={2021}, month={Aug}, pages={e0256224} }
 @article{ahmed_williams_samandar_2018, title={Application of a Discontinuous Form of Macroscopic Gazis-Herman-Rothery Model to Steady-State Freeway Traffic Stream Observations}, volume={2672}, ISSN={["2169-4052"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85060947455&partnerID=MN8TOARS}, DOI={10.1177/0361198118799166}, abstractNote={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.}, number={20}, journal={TRANSPORTATION RESEARCH RECORD}, author={Ahmed, Ishtiak and Williams, Billy M. and Samandar, M. Shoaib}, year={2018}, month={Dec}, pages={51–62} }
 @article{samandar_williams_ahmed_2018, title={Weigh Station Impact on Truck Travel Time Reliability: Results and Findings from a Field Study and a Simulation Experiment}, volume={2672}, ISSN={["2169-4052"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85052711188&partnerID=MN8TOARS}, DOI={10.1177/0361198118791667}, abstractNote={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.}, number={9}, journal={TRANSPORTATION RESEARCH RECORD}, author={Samandar, M. Shoaib and Williams, Billy M. and Ahmed, Ishtiak}, year={2018}, month={Dec}, pages={120–129} }