Identification of Operational Design Domain for Autonomous Truck Mounted Attenuator System on Multilane Highways

2021 ◽  
pp. 036119812110615
Author(s):  
Qing Tang ◽  
Xianbiao Hu ◽  
Hong Yang
Keyword(s):  
Discharge Rate ◽  
Design Domain ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Flow Models ◽  
Effective Discharge ◽  
Discharge Rates ◽  
Operational Design ◽  
Traffic Flow Models ◽  
Key Indicators

The Autonomous Truck Mounted Attenuator (ATMA) vehicle system is a technology that leverages connected and automated vehicle (CAV) capabilities for maintenance of transportation infrastructure. Promoted by FHWA and state departments of transportation (DOTs), it is a niche CAV application in leader–follower style, intended to remove DOT workers from the following maintenance truck, to reduce fatalities in work zones. Because practicable guidance for deployment of this technology is largely missing in MUTCD, state DOTs have been making their own deployment criteria. In this manuscript, we focus on the operational design domain (ODD) problem—under what traffic conditions should ATMA be deployed. Modeling efforts are first focused on the derivation of an effective discharge rate that can be associated with a moving bottleneck caused by slow-moving ATMA vehicles on a multilane highway. Then, based on the demand input and discharge rates, microscopic traffic flow models calculate vehicle delay and density, which the Highway Capacity Manual (HCM) suggests are key indicators of a multilane highway’s level of service (LOS). In this way, the linkage between AADT and LOS is analytically established. NGSIM data is used for the model validation and shows that the developed model correctly captures the effective discharge rate discount caused by moving bottlenecks. The modeling results demonstrate that roadway performance is sensitive to the K factor and D factor, as well as the operating speed of ATMA and, if LOS = C is a desirable design objective, a good AADT threshold to use would be around 40,000 vehicles per day.

Whirling Disease: Reviews and Current Topics

2002 ◽  
Keyword(s):  
Direct Current ◽  
Discharge Rate ◽  
Polar Filament ◽  
Pulse Length ◽  
Submaxillary Gland ◽  
Effective Discharge ◽  
Discharge Rates ◽  
Phosphate Salts ◽  
Fish Hosts ◽  
Chloride Salts

<em>ABSTRACT. </em>The ability of several compounds to discharge the polar filaments of polar capsules of the triactinomyxon stage of <em>Myxobolus cerebralis </em>was tested. Premature polar filament discharge may provide a means for preventing the infective stage of myxozoan parasites from attaching to fish hosts. The discharge regimes evaluated included high and low pH, chloride and phosphate salts, calcium chelators, direct current, mucus, tricaine methanesulfonate anesthetic, neurochemicals, and chemosensitizing agents that are effective discharge agents for members of the phylum Cnidaria. Polar filament discharge, in response to HCl or NaOH, did not differ from controls until pH levels dropped to 1.1 or increased to 11.7. Among the chloride salts tested (NaCl, KCl, CaCl<sub>2</sub>, NH<sub>4</sub>Cl, MgCl<sub>2</sub>), discharge increased at concentrations ranging from 3.1 to 100‰. Discharge varied among the salts tested, peaking at 71% for 100‰ KCl; however, the phosphate salts K<sup>+ </sup>and Na<sup>+ </sup>did not differ in discharge ability. Comparison among KCl, KI, and KPO<sub>4 </sub>indicated that Cl<sup>- </sup>was significantly more effective at both 6.2‰ (45.6% discharge) and 12.5‰ (57.8%) than the other anions. The calcium chelators sodium citrate and EGTA did not induce any significant increase in discharge, nor did the neurochemicals angiotensin, bradykinin, and acetylcholine chloride. Compounds, such as N-acetyl neuraminic acid, proline, and glutathione, that have been reported as chemosensitizers for cnidae discharge among cnidarians, were ineffective discharge agents for triactinomyxon polar capsules. Mucus from rainbow trout or bovine submaxillary gland failed to significantly increase discharge. Attempts to combine mucus with force (stirring rod) or a 0.45 Gauss magnetic field did not increase discharge rates. However, using an electroporator to administer direct current, the discharge rate increased with pulse length (up to 99 µsec) and the number of pulses (0–25). Maximum discharge (98%) and mortality (100%) was observed after 25 99-µsec pulses of 3 kV. Results with electricity indicate a potential for using direct current as a means of disinfection. The data suggest some similarities and differences with similar research on Cnidaria that is discussed.

Headway Compression during Queue Discharge at Signalized Intersections

2005 ◽  
Vol 1920 (1) ◽  
pp. 81-85 ◽  
Author(s):  
Feng-Bor Lin ◽  
Daniel R. Thomas
Keyword(s):  
New York ◽  
Discharge Rate ◽  
Green Light ◽  
The United States ◽  
Signalized Intersections ◽  
Discharge Characteristics ◽  
Traditional Concept ◽  
Highway Capacity Manual ◽  
Discharge Rates ◽  
Saturation Flow

Current methodologies for estimation of intersection capacity are based mainly on the concept of saturation flow. Saturation flow is the steady maximum queue discharge rate after the green light is turned on. According to the U.S. Highway Capacity Manual, this steady maximum rate is generally reached after the fourth queuing vehicle is discharged. Two recent studies conducted in Hawaii and Taiwan, however, have found that queue discharge headways tend to undergo compression for a considerable time as more vehicles in the same queue are discharged. Consequently, queue discharge rates often kept rising even after the 15th vehicle has entered the intersection. If this queue discharge characteristic is common in the United States, then there is a need to assess the implications of con-tinued use of the traditional concept of saturation flow rate for capacity analysis of signalized intersections. To provide insight into this potential problem, this study examines the queue discharge characteristics at three intersections on Long Island, New York. The queue discharge characteristics at all three intersections were found to be similar to those observed in Taiwan and Hawaii.

Queue Analysis at Work Zones from Field-Collected Data

2021 ◽  
pp. 036119812110252
Author(s):  
Julius Codjoe ◽  
Raju Thapa ◽  
Elisabeta Mitran
Keyword(s):  
Flow Rate ◽  
Discharge Rate ◽  
Time Of Day ◽  
Work Zone ◽  
Speed Ratio ◽  
Work Zones ◽  
Highway Capacity ◽  
Local Data ◽  
Highway Capacity Manual ◽  
Annual Average Daily Traffic

Estimation of the capacity of work zones is vital to manage the possibility of traffic flows exceeding capacity and resulting in unbearable queues during work zone lane closures. A plethora of research papers have studied several ways to estimate work zone capacity, with the Highway Capacity Manual (HCM) having its own methodology to estimate capacity based on various site characteristics. However, HCM always recommends validating its model with local data to reflect the actual driving behavior of the region. This study considered work zone capacity as a function of queue discharge rate (QDR), defined as the 15-min average flow rate immediately after breakdown, also known as postbreakdown flow rate. By collecting data from 10 different work zones within the state of Louisiana, the study estimated QDR and its corresponding duration at breakdowns. An average QDR of 1,664 pcphpl and an associated queue of 120 min average duration was found. Analysis of variance showed that average QDRs across all sites were not significantly different. The QDR prediction model revealed that a closed right lane and a work zone on linear roadways significantly increased the discharge rate. However, the presence of nearby exit ramps, daytime scenarios, and an increase in the speed ratio and truck percentages were found to decrease the discharge rate. A separate model for the duration of queue or breakdown found the time of day, change in the speed ratio, presence of entry ramp, location of work zones, and annual average daily traffic of the roadway to be significant variables.

Saturation Flows at Signal-Group-Controlled Traffic Signals

1997 ◽  
Vol 1572 (1) ◽  
pp. 24-32 ◽  
Author(s):  
Jarkko Niittymäki ◽  
Matti Pursula
Keyword(s):  
Field Measurements ◽  
External Factors ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Flow Models ◽  
Control Programs ◽  
Extensive Field ◽  
Lane Width ◽  
Traffic Composition ◽  
Saturation Flow

The main goal of this research was to update the basic saturation flow values of signalized intersections. The secondary goal was to analyze the effects of certain external factors (such as weather, road, and traffic conditions) on saturation flow. The updating is based on extensive field measurements and simulations. Altogether, about 39,000 queues were observed in this study. Field measurements at 30 locations were made according to the method described in the Highway Capacity Manual and simulations were done with the Helsinki University of Technology HUT-SIM simulator, which was calibrated and carefully validated for Finnish road conditions. A summary of calibration parameters is also presented. The new base value for straight-through lanes is 1, 940 vehicles per hour; the previous value was 1, 700 vehicles per hour. In general, the updated saturation flow values of different lane types are 5 to 20 percent larger than the previous base values. The saturation flow models of different lane types are described. The effects of geometric and traffic composition factors, such as percentage of turning vehicles, traffic composition, lane width, and approach grade, were examined and modeled. Effects of weather, road surface, light conditions, and speed level were also analyzed. The drop in saturation flow was about 20 to 30 percent under slippery road and snowy conditions. In rainy conditions, the drop was smaller, about 10 percent. The effect of speed on saturation flow is also described. The most important results of this 2-year project are the saturation flow values for different lane types, knowledge of the effect of external factors (especially during winter), and the large database, which can be used for other purposes. The possibility of using special signal control programs under bad road conditions is discussed. With these kinds of programs, better safety and higher capacity can be achieved.

Stochastic Traffic Flow Models of the National Airspace System

2008 ◽  
Author(s):  
Monish Tandale ◽  
Jinwhan Kim ◽  
Karthik Palaniappan ◽  
P. K. Menon ◽  
Jay Rosenberger ◽  
...  
Keyword(s):  
Traffic Flow ◽  
National Airspace System ◽  
Flow Models ◽  
Traffic Flow Models

The ENT emergency clinic: does senior input matter?

2012 ◽  
Vol 127 (1) ◽  
pp. 15-19 ◽  
Author(s):  
A Mirza ◽  
L McClelland ◽  
M Daniel ◽  
N Jones
Keyword(s):  
Quality Of Care ◽  
Discharge Rate ◽  
Surrogate Marker ◽  
Operating Theatre ◽  
Number Of Children ◽  
Discharge Rates ◽  
Time Period ◽  
Number Of Patients

AbstractBackground:Many ENT conditions can be treated in the emergency clinic on an ambulatory basis. Our clinic traditionally had been run by foundation year two and specialty trainee doctors (period one). However, with perceived increasing inexperience, a dedicated registrar was assigned to support the clinic (period two). This study compared admission and discharge rates for periods one and two to assess if greater registrar input affected discharge rate; an increase in discharge rate was used as a surrogate marker of efficiency.Method:Data was collected prospectively for patients seen in the ENT emergency clinic between 1 August 2009 and 31 July 2011. Time period one included data from patients seen between 1 August 2009 and 31 July 2010, and time period two included data collected between 1 August 2010 and 31 July 2011.Results:The introduction of greater registrar support increased the number of patients that were discharged, and led to a reduction in the number of children requiring the operating theatre.Conclusion:The findings, which were determined using clinic outcomes as markers of the quality of care, highlighted the benefits of increasing senior input within the ENT emergency clinic.

Modeling Capacity of Through Movement at Signalized Intersection Affected by Short Left-Turn Bay under Different Signal Settings

2021 ◽  
pp. 036119812110064
Author(s):  
Zihang Wei ◽  
Yunlong Zhang ◽  
Xiaoyu Guo ◽  
Xin Zhang
Keyword(s):  
Cycle Length ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Essential Factor ◽  
Highway Capacity ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Proposed Model ◽  
Vehicle Demand ◽  
The One

Through movement capacity is an essential factor used to reflect intersection performance, especially for signalized intersections, where a large proportion of vehicle demand is making through movements. Generally, left-turn spillback is considered a key contributor to affect through movement capacity, and blockage to the left-turn bay is known to decrease left-turn capacity. Previous studies have focused primarily on estimating the through movement capacity under a lagging protected only left-turn (lagging POLT) signal setting, as a left-turn spillback is more likely to happen under such a condition. However, previous studies contained assumptions (e.g., omit spillback), or were dedicated to one specific signal setting. Therefore, in this study, through movement capacity models based on probabilistic modeling of spillback and blockage scenarios are established under four different signal settings (i.e., leading protected only left-turn [leading POLT], lagging left-turn, protected plus permitted left-turn, and permitted plus protected left-turn). Through microscopic simulations, the proposed models are validated, and compared with existing capacity models and the one in the Highway Capacity Manual (HCM). The results of the comparisons demonstrate that the proposed models achieved significant advantages over all the other models and obtained high accuracies in all signal settings. Each proposed model for a given signal setting maintains consistent accuracy across various left-turn bay lengths. The proposed models of this study have the potential to serve as useful tools, for practicing transportation engineers, when determining the appropriate length of a left-turn bay with the consideration of spillback and blockage, and the adequate cycle length with a given bay length.

Assessment of Arterial Signal Timings Based on Various Operational Policies and Optimization Tools

2021 ◽  
pp. 036119812110111
Author(s):  
Suhaib Al Shayeb ◽  
Nemanja Dobrota ◽  
Aleksandar Stevanovic ◽  
Nikola Mitrovic
Keyword(s):  
Travel Time ◽  
Heavy Traffic ◽  
Future Research ◽  
Signal Timing ◽  
Highway Capacity ◽  
Average Delay ◽  
Highway Capacity Manual ◽  
Simulation And Optimization ◽  
Fort Lauderdale ◽  
Design Engineers

Traffic simulation and optimization tools are classified, according to their practical applicability, into two main categories: theoretical and practical. The performance of the optimized signal timing derived by any tool is influenced by how calculations are executed in the particular tool. Highway Capacity Software (HCS) and Vistro implement the procedures defined in the Highway Capacity Manual, thus they are essentially utilized by traffic operations and design engineers. Considering its capability of timing diagram drafting and travel time collection studies, Tru-Traffic is more commonly used by practitioners. All these programs have different built-in objective function(s) to develop optimized signal plans for intersections. In this study, the performance of the optimal signal timing plans developed by HCS, Tru-Traffic, and Vistro are evaluated and compared by using the microsimulation software Vissim. A real-world urban arterial with 20 intersections and heavy traffic in Fort Lauderdale, Florida served as the testbed. To eliminate any bias in the comparisons, all experiments were performed under identical geometric and traffic conditions, coded in each tool. The evaluation of the optimized plans was conducted based on average delay, number of stops, performance index, travel time, and percentage of arrivals on green. Results indicated that although timings developed in HCS reduced delay, they drastically increased number of stops. Tru-Traffic signal timings, when only offsets are optimized, performed better than timings developed by all of the other tools. Finally, Vistro increased arrivals on green, but it also increased delay. Optimized signal plans were transferred manually from optimization tools to Vissim. Therefore, future research should find methods for automatically transferring optimized plans to Vissim.

scholarly journals Analysis of ATO System Operation Scenarios Based on UPPAAL and the Operational Design Domain

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 503
Author(s):  
Zicong Meng ◽  
Tao Tang ◽  
Guodong Wei ◽  
Lei Yuan
Keyword(s):  
High Speed ◽  
Test Case ◽  
Design Domain ◽  
System Operation ◽  
High Speed Railway ◽  
Functional Specification ◽  
Operational Design ◽  
Train Operation ◽  
System Requirements ◽  
Automatic Train Operation

With the gradual maturity of the automatic train operation (ATO) system in subways, its application scope has also expanded to the high-speed railway field. Considering that the ATO system is still in the early stages of operation, it will take time to fully mature, and definite specifications of the requirements for system operation have not yet been formed. This paper presents the operational design domain (ODD) of the high-speed railway ATO system and proposes a scenario analysis method based on the operational design domain to obtain the input conditions of the system requirements. The article models and verifies the scenario of the linkage control of the door and platform door based on the UPPAAL tools and extracts the input and expected output of the system requirements of the vehicle ATO system. Combined with the input conditions of the system requirements, the system requirements of the vehicle ATO in this scenario are finally obtained, which provides a reference for future functional specification generation and test case generation.

Sign in / Sign up

Export Citation Format

Share Document