High-volume Scenarios Research Articles

Traffic signal coordination control for arterials with dedicated CAV lanes

Purpose This study aims to make full use of the advantages of connected and autonomous vehicles (CAVs) and dedicated CAV lanes to ensure all CAVs can pass intersections without stopping. Design/methodology/approach The authors developed a signal coordination model for arteries with dedicated CAV lanes by using mixed integer linear programming. CAV non-stop constraints are proposed to adapt to the characteristics of CAVs. As it is a continuous problem, various situations that CAVs arrive at intersections are analyzed. The rules are discovered to simplify the problem by discretization method. Findings A case study is conducted via SUMO traffic simulation program. The results show that the efficiency of CAVs can be improved significantly both in high-volume scenario and medium-volume scenario with the plan optimized by the model proposed in this paper. At the same time, the progression efficiency of regular vehicles is not affected significantly. It is indicated that full-scale benefits of dedicated CAV lanes can only be achieved with signal coordination plans considering CAV characteristics. Originality/value To the best of the authors’ knowledge, this is the first research that develops a signal coordination model for arteries with dedicated CAV lanes.

Euclid: A Fully In-Network, P4-Based Approach for Real-Time DDoS Attack Detection and Mitigation

Distributed Denial-of-Service (DDoS) attacks have been steadily escalating in frequency, scale, and disruptiveness - with outbreaks reaching multiple terabits per second and compromising the availability of highly-resilient networked systems. Existing defenses require frequent interaction between forwarding and control planes, making it difficult to reach a satisfactory trade-off between accuracy (higher is better), resource usage, and defense response delay (lower is better). Recently, high-performance programmable data planes have made it possible to develop a new generation of mechanisms to analyze and manage traffic at line rate. In this article, we explore P4 language constructs and primitives to design Euclid, a fully in-network fine-grained, low-footprint, and low-delay traffic analysis mechanism for DDoS attack detection and mitigation. Euclid utilizes information-theoretic and statistical analysis to detect attacks and classify packets as either legitimate or malicious, thus enabling the enforcement of policies (e.g., discarding, inspection, or throttling) to prevent attack traffic from disrupting the operation of its victims. We experimentally evaluate our proposed mechanism using packet traces from CAIDA. The results indicate that Euclid can detect attacks with high accuracy (98.2%) and low delay (≈250 ms), and correctly identify most of the attack packets (>96%) without affecting more than 1% of the legitimate traffic. Furthermore, our approach operates under a small resource usage footprint (tens of kilobytes of static random-access memory per 1 Gbps link and a few hundred ternary content-addressable memory entries), thus enabling its deployability on high-throughput, high-volume scenarios.

Microsimulation of energy and flow effects from optimal automated driving in mixed traffic

This paper studies the energy and traffic impact of a proposed Anticipative Cruise Controller in a PTV VISSIM microsimulation environment. We dissect our controller into two parts: 1. the unconnected mode, active when following a human-driven vehicle, and 2. the connected mode, active when following another automated vehicle equipped with connectivity. Probabilistic constraints balance safety considerations with inter-vehicle compactness, and vehicle constraints for acceleration capabilities are expressed through the use of powertrain maps. Emergent highway traffic scenarios are then modeled using time headway distributions from empirical traffic data. To study the impact of automation over a range of demands of free-flow to stop-and-go, we vary vehicle flux from low to high and vary automated vehicle penetration from low to high. When examining all-human driving scenarios, network capacity failed to meet demand in high-volume scenarios, such as rush-hour traffic. We further find that with connected automated vehicles introduced, network capacity was improved to support the high-volume scenarios. Finally, we examine energy efficiencies of the fleet for conventional, electric, and hybrid vehicles. We find that automated vehicles perform at a 10%–20% higher energy efficiency over human drivers when considering conventional powertrains, and find that automated vehicles perform at a 3%–9% higher energy efficiency over human drivers when considering electric and hybrid powertrains. Due to secondary effects of smoothing traffic flow and reducing unnecessary braking, energy benefits also apply to human-driven vehicles that interact with automated ones. Such simulated humans were found to drive up to 10% more energy-efficiently than they did in the baseline all-human scenario.

Facilitating pandemic influenza vaccination implementation in grocery store chain community pharmacies

ObjectiveThe objective of this study was to determine strategies to implement influenza pandemic vaccinations effectively at grocery store chain community pharmacies. MethodsClinical pharmacy coordinators and pharmacy managers representing 3 grocery store chain community pharmacies across Pennsylvania were identified for participation in semistructured telephone interviews. Interviews were audio-recorded and transcribed. Transcripts were independently coded by 2 investigators and coding discrepancies were resolved. A thematic analysis was conducted, and supporting quotes were selected for each theme. ResultsTwelve pharmacists participated in the interviews, which were conducted from September 2016 to November 2017. Five key themes were identified: (1) mobilize pharmacy staff members to specific locations to prepare for a high volume of vaccinations; (2) implement vaccination clinics during high-volume scenarios; (3) utilize nonpharmacy spaces to increase vaccination capabilities; (4) determine vaccine distribution by highest risk populations that each pharmacy serves; and (5) conduct training customized to the pharmacy chain that supplements national pandemic influenza training. ConclusionGrocery store chain community pharmacies are desirable sites for pandemic vaccination because of a variety of factors, such as space and staffing flexibility. Developing a pandemic vaccination plan will enable community pharmacists to contribute more effectively during influenza pandemics.

312 Language Diversity and Challenges to Communication in Indian Emergency Departments

While communication is always a challenge in health care delivery, emergency departments (ED) in India have an added layer of complexity as the population displays significant language diversity with regional variations. Prior research done in India revealed challenges in language and communication as barriers to care. The objective of this study was to better understand the challenges to effective communication pertaining to patient and provider interactions in a sample of EDs in India in order to determine strategies for improvement. This study was carried out in the summer of 2017 at 6 collaborating sites across India. Semi-structured interviews were conducted with the emergency medical services (EMS) staff/techs, nurses, residents, and attending physicians working in the ED. The interview questions were designed to capture themes pertaining to patient-provider and provider-provider interactions. The data was analyzed using a rapid assessment process. A total of 106 participants were interviewed in a combination of group and individual interviews. This included 20 EMS staff/techs, 20 nurses, 52 residents, and 14 ED attending physicians. Within provider-patient interactions, the theme of language discordance was frequently identified as an issue. While translator services were often provided by the hospital for international patients, examples were cited with no formal translation for domestic out-of-state patients. Resident physicians from out-of-state reported having to learn the local language with help from colleagues; however, they often recalled adverse events occurring, especially in the first year. Participants reported that low health literacy among patients and family members, a paucity of widely-known medical terms in the local language, and an overall reluctance to accept the severity of medical diagnoses further complicated effective communication. All of these issues contributed to examples of challenging patient care scenarios. When discussing provider-provider communication, many participants cited positive experiences, often referring to their coworkers as their ED family. Upon further probing, situations were identified during which communication challenges were noted, including patient handover, high volume scenarios, and times of provider fatigue. Providers also cited workplace hierarchy as an obstacle to open channels of communication. In addition, EMS staff/techs, nurses, and physicians reported inconsistencies in written and verbal orders as a source of confusion, especially during high patient volumes. This study documents the impact of language diversity and communication barriers in the setting of Indian EDs. The findings revealed the impact the use of multiple languages had on interactions with patients and amongst providers. The results highlight the need to develop effective means to communicate health information to patients of low health literacy, prepare patients for the flow of the ED system, and provide residents language training support. More widespread translator services may be an important tool to consider in the future.

Probability of Secondary Crash Occurrence on Freeways with the Use of Private-Sector Speed Data

A percentage of crashes on freeways are suspected to be caused in part by congestion or distraction from earlier incidents. Identification and prevention of these secondary crashes are major goals of transportation agencies, yet the characteristics of secondary crashes—in particular the probability of their occurrence—are poorly understood. Many secondary crashes occur when a vehicle encounters nonrecurring congestion, yet previous efforts to identify incident queues and their secondary crashes have relied either on deterministic queuing theory or on data from uniformly spaced dense loop detectors. This study is the first analysis of secondary crash occurrence to integrate incident timelines and traffic volumes with widely available and legally obtained private-sector speed data. Analysis found that 9.2% of all vehicle crashes were secondary to another incident and that 6.2% of these crashes were tertiary to another primary incident. Secondary crashes occurred on average once every 10 crashes and 54 disabled vehicles. The findings support a fast incident response, because the probability of a secondary crash occurrence increases approximately 1 percentage point for every additional 2 to 3 min spent on the scene in high-volume scenarios.

Evaluation of Three Influenza Neuraminidase Inhibition Assays for Use in a Public Health Laboratory Setting during the 2011–2012 Influenza Season

We evaluated the implementation of three commercially available neuraminidase inhibition assays in a public health laboratory (PHL) setting. We also described the drug susceptibility patterns of human influenza A and B circulating in Maryland during the 2011-2012 influenza season. From January to May 2012, 169 influenza virus isolates were tested for phenotypic susceptibility to oseltamivir, zanamivir, and peramivir using NA-Fluor(TM), NA-Star®, and NA-XTD(TM) concurrently. A 50% neuraminidase inhibitory concentration (IC50) value was calculated to determine drug susceptibility. We used the standard deviation based on the median absolute deviation of the median analysis to determine the potential for reduced drug susceptibility. We evaluated each assay for the use of resources in high- and low-volume testing scenarios. One of the 25 2009 influenza A (H1N1) pandemic isolates tested was resistant to oseltamivir and peramivir, and sensitive to zanamivir, on all three platforms. Eighty-two influenza A (H3N2) and 62 B isolates were sensitive to all three drugs in all three assays. For a low-volume scenario, NA-Star and NA-XTD took 120 minutes to complete, while NA-Fluor required 300 minutes to complete. The lowest relative cost favored NA-Star. In a high-volume scenario, NA-Fluor had the highest throughput. Reagent use was most efficient when maximizing throughput. Cost efficiency from low- to high-volume testing improved the most for NA-Star. Our evaluation showed that both chemiluminescent and fluorescent neuraminidase inhibition assays can be successfully implemented in a PHL setting to screen circulating influenza strains for neuraminidase inhibitor resistance. For improved PHL influenza surveillance, it may be essential to develop guidelines for phenotypic drug-resistance testing that take into consideration a PHL's workload and available resources.

Performance Analysis of Parallel Flow Intersection and Displaced Left-Turn Intersection Designs

The displaced left-turn (DLT) design, also known as the continuous flow intersection, has proved to be a superior alternative to the conventional intersection in terms of handling heavy volumes during peak periods. In locations where the availability of additional right-of-way and driveway access is not a major concern, the DLT design is a cost-effective and time-saving option compared with the expensive option of grade-separated interchanges. Recently, a new nontraditional intersection design called the parallel flow intersection (PFI) has been proposed. The PFI is also an at-grade design and operates with the same number of signal phases as a DLT. This research compares the operational performance of DLT and PFI designs based on the maximum through and left-turn movement throughputs for three different high-volume scenarios using traffic simulation. The results indicate that maximum throughput values of through movement in the PFI were very close to the values obtained for the DLT. The designs produced similar results, mainly because both operate as two-phase signals (at the main intersection) with equal green times for through movements. The left-turn movement throughputs in the PFI were found to be lower than those in the DLT. For two study cases, the DLT was able to process 180 and 80 more vehicles per hour per lane than the PFI. This is attributable to left-turning vehicles experiencing a greater number of stops, on average, in a PFI than they would in a DLT.

Comparison of Two Unconventional Intersection Schemes

The operational performance of signalized intersections can be significantly affected by heavy left-turn movements. Therefore, several measures to improve the performance of intersections with heavy left-turn movements, including some unconventional schemes, have been investigated. In this paper the performance of two of these unconventional schemes, namely, the crossover displaced left-turn (XDL) intersection and the upstream signalized crossover (USC) intersection, is compared. The XDL intersection eliminates left-turn opposing conflicts by displacing the left-turn lane to the opposing direction and crossing the left-traffic to the left side of the road before the intersection. The USC intersection eliminates left-turn opposing conflicts by crossing both the left and through traffic to the left side of the road before the intersection. The microsimulation software VisSim was used to analyze the two unconventional intersections for comparison. The analysis showed that the XDL outperforms the conventional intersection under various volume scenarios. In contrast, the USC outperforms the conventional intersection under moderate- and high-volume conditions or in the existence of extremely heavy left-turn movements. The results showed that the USC and the XDL exhibit similar average delays in low-, moderate-, and moderately high-volume conditions, with the XDL slightly outperforming the USC. However, the XDL significantly outperforms the USC under high-volume scenarios. The XDL has, as a basic design element, a left-turn bay that extends between the primary and the secondary intersections. The existence of this bay is probably the main reason for the high capacity of the XDL. Such an additional bay requires more right-of-way and higher construction costs than USC.