Browsing by Author "Park, Hyungjun"

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    Connected Vehicle Enabled Freeway Merge Management – Field Test
    Smith, Brian L.; Park, Hyungjun; Hayat, Md Tanveer (Connected Vehicle/Infrastructure University Transportation Center (CVI-UTC), 2016-01-01)
    Freeway congestion is a major problem of the transportation system, resulting in major economic loss in terms of traffic delays and fuel costs. With connected vehicle (CV) technologies, more proactive traffic management strategies are possible. The Freeway Merge Assistance System (FMAS) can implement innovative ramp management strategies by providing personalized advisories to individual drivers to ensure smoother merging. The benefits anticipated from these strategies will completely depend on the advisory compliance of the drivers; this, in turn, will be influenced by situational as well as individual behavioral factors. The purpose of this research was to investigate drivers’ responses to this new generation of personalized in-vehicle advisory messages. A field test was conducted with naïve human subjects to collect driver behavior data about different types of advisory messages under different traffic scenarios in a controlled environment. The data gathered from the field test indicated that the compliance rate was higher when a large- or medium-size gap was available for a lane change. The lowest compliance rate was observed for a small-gap scenario. In addition, it was discovered that more drivers would follow a direct advisory message that advised a lane change rather than an indirect message which was meant to stimulate a lane change through speed control.
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    A Connected Vehicle–Enabled Virtual Dynamic Message Sign System Demonstration and Evaluation on the Virginia Connected Vehicle Test Bed
    Park, Hyungjun; Babiceanu, Simona; Kluger, Robert; Smith, Brian L.; Recht, David (Connected Vehicle/Infrastructure University Transportation Center, 2016-03-15)
    Dynamic message signs (DMSs) are widely used to deliver traveler information. While these have proven to be effective, key limitations exist: (1) the locations of DMSs are fixed, (2) reading a DMS message is distracting to drivers, and (3) installation and maintenance of DMSs is expensive. To address these limitations, a smartphone-based virtual DMS (VDMS) application was developed in the first round of Connected Vehicle/Infrastructure University Transportation Center (CVI-UTC) projects. This application used smartphones to provide audible “reading” of DMS messages to drivers. This project built upon previous work to develop a more advanced, second generation of the VDMS system, that is fully integrated in the Dedicated Short Range Communications (DSRC) environment of the Virginia Connected Vehicle Test Bed. The highlights of the enhanced VDMS system include (1) use of four of 40+ DSRC-based roadside equipment units (RSEs) on the Virginia Connected Vehicle Test Bed, and (2) software (VDMS Manager) that has the capability to virtually “build” new DMSs and to create modified and new messages for those DMSs. To evaluate the VDMS system as an information dissemination tool to support advanced traffic management, operational testing (including three surveys, entrance, post-incident, and exit) was carried out with actual operators at the McConnell Public Safety and Traffic Operations Center. It was observed that operators preferred the VDMS system due to its capability of providing more detailed and customized messages at more appropriate locations for motorists.
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    Infrastructure Safety Assessment in a Connected Vehicle Environment
    Smith, Brian L.; Kluger, Robert; Park, Hyungjun (Connected Vehicle/Infrastructure University Transportation Center (CVI-UTC), 2015-12-15)
    The goal of the Infrastructure Safety Assessment in a Connected Vehicle (CV) Environment project was to develop a method to identify infrastructure safety “hot spots” using CV data. Using these basic safety messages to detect hot spots may allow for quicker discovery than traditional methods, such as police-reported crashes. The basic safety message may be able to detect events that police normally cannot obtain, including unreported crashes and near-crashes. The project successfully explored some models and algorithms to detect crashes and near-crashes and also designed a methodology to apply to hot spot identification. With the data available, conclusive results were not achieved; however, the models showed some potential. Three techniques were tested to predict crashes using vehicles’ kinematic data. To predict where a crash was occurring, multivariate adaptive regression splines, classification and regression trees, and a novel pattern matching approach were all tested. The models were able to identify the majority of 13 known crashes with different amounts of false positives. The pattern matching approach outperformed a simple acceleration threshold by identifying nearly 70% of crashes in a crash- only test set and 74% of near-crashes in a near-crash only test set. On the training set, it was able to identify more crashes than the thresholds without increasing the number of false positives observed. Based on the work described in this report, the CVI-UTC is fully prepared to apply the methodology to data collected on the field test bed.
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    Prototyping and Evaluating a Smartphone Dynamic Message Sign (DMS) Application
    Smith, Brian L.; Ma, Jiaqi; Park, Hyungjun (Connected Vehicle/Infrastructure University Transportation Center (CVI-UTC), 2015-12-15)
    Traveler Information Systems are designed and operated by transportation agencies to provide travelers with real-time traffic information, enabling them to make better travel decisions. One of the most commonly used ways to provide real-time, en route traveler information to motorists is through Dynamic Message Signs (DMSs). Despite their effectiveness, they are costly and limited in terms of the amount of information they can deliver. The wide availability of smart mobile devices can provide traveler information through in-vehicle devices (without incurring huge infrastructure costs) and (in a more flexible manner) to selected individuals and locations without geographical constraints. Research was conducted to comprehensively develop and evaluate this concept and a summary of tasks and findings is presented below. First, this research proposed the concept of a Virtual Dynamic Message Sign (VDMS) system utilizing a smartphone-based application to demonstrate and summarize user experience for future deployment. The user survey revealed a positive attitude among participants toward a VDMS system in terms of both usefulness and satisfaction; the average ratings were −0.90 and −0.81 respectively on a −2 to 2 (Totally agree to Totally disagree) five-point Likert scale. The survey also indicated that most drivers (81.0%) perceived VDMS as a safer way to receive information. Many drivers (66.7%) also felt more comfortable receiving an audible message from a VDMS system rather than a text message on a DMS. The results indicate great user acceptability and the potential for such systems to be deployed by public agencies in the future. This research also aimed to address the question of whether a VDMS conveys information at least as effectively as existing DMSs. A mixed, repeated-measure experiment was designed using a driver simulator to examine (1) the impacts of driver age, (2) information transmission mode, (3) amount of information, and (4) driving complexity on message comprehension, distraction, and perceived difficulty. Forty-two people were recruited and each of them participated in a test under different combinations. Participant performance was measured in terms of message comprehension, distraction, and self-reported message difficulty level. Results revealed that VDMS generally performs better than DMS across different amounts of information, under different driving conditions, and regardless of driver age. VDMS proved significantly better than DMS in message comprehension under relatively complex conditions. It reduced reaction time to unexpected stimuli (as measured with a reduced time-to-brake of 0.39 seconds), and made the same messages easier to process and retain for drivers than DMS. Based on these results, it is recommended that transportation agencies give careful consideration to VDMS as a future strategy for delivering public traffic information in a connected vehicle environment.