Analysis of Freeway Traffic Incident Conditions by Using Second-Order Spatiotemporal Traffic Performance Measures

2005 ◽  
Vol 1925 (1) ◽  
pp. 20-28 ◽  
Author(s):  
Sherif Ishak ◽  
Ciprian Alecsandru
Keyword(s):  
Performance Measures ◽  
Second Order ◽  
Operating Conditions ◽  
Data Sets ◽  
Freeway Traffic ◽  
Contour Maps ◽  
Traffic Conditions ◽  
Statistical Measures ◽  
Study Results ◽  
Texture Characterization

The characteristics of preincident, postincident, and nonincident traffic conditions on freeways are investigated. The characteristics are defined by second-order statistical measures derived from spatiotemporal speed contour maps. Four performance measures are used to quantify properties such as smoothness, homogeneity, and randomness in traffic conditions in a manner similar to texture characterization of digital images. With real-world incident and traffic data sets, statistical analysis was conducted to seek distinctive characteristics of three groups of traffic operating conditions: preincident, postincident, and nonincident. The study results showed that the spatiotemporal characteristics of each of the three groups were not discernible. Although the distributions of performance measures within each group are statistically different, no consistent pattern was detected to imply that certain characteristics could increase the likelihood of incidents or identify precursory conditions to incidents.

Deriving Traffic-Performance Measures and Levels of Service from Second-Order Statistical Features of Spatiotemporal Traffic Contour Maps

2003 ◽  
Vol 1858 (1) ◽  
pp. 148-157 ◽  
Author(s):  
Sherif Ishak
Keyword(s):  
Intelligent Transportation Systems ◽  
Traffic Management ◽  
Performance Monitoring ◽  
Transportation Systems ◽  
Second Order ◽  
Level Of Service ◽  
Large Set ◽  
Contour Map ◽  
Contour Maps ◽  
Statistical Measures

Little information has been successfully extracted from the wealth of data collected by intelligent transportation systems. Such information is needed for the efficiency of operations and management functions of traffic-management centers. A new set of second-order statistical measures derived from texture characterization techniques in the field of digital image analysis is presented. The main objective is to improve the data-analysis tools used in performance-monitoring systems and assessment of level of service. The new measures can extract properties such as smoothness, homogeneity, regularity, and randomness in traffic operations directly from constructed spatiotemporal traffic contour maps. To avoid information redundancy, a correlation matrix was examined for nearly 14,000 15-min speed contour maps generated for a 3.4-mi freeway section over a period of 5 weekdays. The result was a set of three second-order measures: angular second moment, contrast, and entropy. Each measure was analyzed to examine its sensitivity to various traffic conditions, expressed by the overall speed mean of each contour map. The study also presented a tentative approach, similar to the conventional one used in the Highway Capacity Manual, to evaluate the level of service for each contour map. The new set of level-of-service criteria can be applied in real time by using a stand-alone module that was developed in the study. The module can be readily implemented online and allows traffic-management center operators to tune a large set of related parameters.

Evaluating Freeway Traffic Conditions by Data Envelopment Analysis Using Loop Data

2011 ◽  
Vol 181-182 ◽  
pp. 890-895
Author(s):  
Shen Zhang ◽  
Shi An
Keyword(s):  
Data Envelopment Analysis ◽  
Performance Measures ◽  
Evaluation Method ◽  
Data Envelopment ◽  
Freeway Traffic ◽  
Traffic Conditions ◽  
Loop Detectors ◽  
Time Loop ◽  
Freeway Congestion ◽  
Insight Into

Effective evaluation of traffic conditions is a key issue involved in alleviating freeway congestion, improving operations and estimating travel time. Loop detectors can provide reliable traffic data sources for traffic conditions measurement and monitoring, however, the multiple influencing factors derived from loop data lead to a combined effect which complicates the measurement. Therefore, a novel traffic conditions evaluation method by utilizing Data Envelopment Analysis (DEA) is proposed. The method can devise an overall traffic conditions evaluation based on the multiple performance measures. To illustrate our method, an experimental study was undertaken with dual-loop-detector data from 6 freeway sections for the year 2006, and 5 measures were selected for inclusion in this multivariate analysis to evaluate the traffic conditions. The conclusions indicate the stakeholders can gain new insight into the overall traffic conditions behind multiple performance measures with our method, and the evaluation results is helpful in identifying transportation investment priorities for specific regions and improving resource utilization among competing sectors.

scholarly journals On the Potential Impacts of Smart Traffic Control for Delay, Fuel Energy Consumption, and Emissions: An NSGA-II-Based Optimization Case Study from Dhahran, Saudi Arabia

2020 ◽  
Vol 12 (18) ◽  
pp. 7394 ◽  
Author(s):  
Mohammed Al-Turki ◽  
Arshad Jamal ◽  
Hassan M. Al-Ahmadi ◽  
Mohammed A. Al-Sughaiyer ◽  
Muhammad Zahid
Keyword(s):  
Saudi Arabia ◽  
Fuel Consumption ◽  
Performance Measures ◽  
Traffic Control ◽  
Traffic Light ◽  
Nsga Ii ◽  
Simulation And Optimization ◽  
Traffic Conditions ◽  
Study Results ◽  
Conflicting Objectives

Intelligent traffic control at urban intersections is vital to ensure efficient and sustainable traffic operations. Urban road intersections are hotspots of congestion and traffic accidents. Poor traffic management at these locations could cause numerous issues, such as longer travel time, low travel speed, long vehicle queues, delays, increased fuel consumption, and environmental emissions, and so forth. Previous studies have shown that the mentioned traffic performance measures or measures of effectiveness (MOEs) could be significantly improved by adopting intelligent traffic control protocols. The majority of studies in this regard have focused on mono or bi-objective optimization with homogenous and lane-based traffic conditions. However, decision-makers often have to deal with multiple conflicting objectives to find an optimal solution under heterogeneous stochastic traffic conditions. Therefore, it is essential to determine the optimum decision plan that offers the least conflict among several objectives. Hence, the current study aimed to develop a multi-objective intelligent traffic control protocol based on the non-dominated sorting genetic algorithm II (NSGA-II) at isolated signalized intersections in the city of Dhahran, Kingdom of Saudi Arabia. The MOEs (optimization objectives) that were considered included average vehicle delay, the total number of vehicle stops, average fuel consumption, and vehicular emissions. NSGA-II simulations were run with different initial populations. The study results showed that the proposed method was effective in optimizing considered performance measures along the optimal Pareto front. MOEs were improved in the range of 16% to 23% compared to existing conditions. To assess the efficacy of the proposed approach, an optimization analysis was performed using a Synchro traffic light simulation and optimization tool. Although the Synchro optimization resulted in a relatively lower signal timing plan than NSGA-II, the proposed algorithm outperformed the Synchro optimization results in terms of percentage reduction in MOE values.

Analyst Performance Measures. Volume 2: Information Quality Tools for Persistent Surveillance Data Sets

2011 ◽  
Author(s):  
Marina Altynova ◽  
Ed Wasser ◽  
Telford Berkey ◽  
Sanjay Boddhu ◽  
Tin Sa ◽  
...  
Keyword(s):  
Performance Measures ◽  
Information Quality ◽  
Surveillance Data ◽  
Data Sets ◽  
Quality Tools

Analyst Performance Measures. Volume 3. Information Quality Tools for Persistent Surveillanec Data Sets

2011 ◽  
Author(s):  
John Talburt ◽  
Serhan Dagtas ◽  
Mariofanna Milanova ◽  
Mihail Tudoreanu ◽  
Brian Tsou
Keyword(s):  
Performance Measures ◽  
Information Quality ◽  
Data Sets ◽  
Quality Tools

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals A Numerical Investigation into the PAT Hydrodynamic Response to Impeller Rotational Speed Variation

2021 ◽  
Vol 13 (14) ◽  
pp. 7998
Author(s):  
Maxime Binama ◽  
Kan Kan ◽  
Hui-Xiang Chen ◽  
Yuan Zheng ◽  
Daqing Zhou ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Distribution Systems ◽  
Water Distribution ◽  
Production Efficiency ◽  
Operating Conditions ◽  
Energy Regulation ◽  
Speed Increase ◽  
Energy Field ◽  
Long Run ◽  
Study Results

The utilization of pump as turbines (PATs) within water distribution systems for energy regulation and hydroelectricity generation purposes has increasingly attracted the energy field players’ attention. However, its power production efficiency still faces difficulties due to PAT’s lack of flow control ability in such dynamic systems. This has eventually led to the introduction of the so-called “variable operating strategy” or VOS, where the impeller rotational speed may be controlled to satisfy the system-required flow conditions. Taking from these grounds, this study numerically investigates PAT eventual flow structures formation mechanism, especially when subjected to varying impeller rotational speed. CFD-backed numerical simulations were conducted on PAT flow under four operating conditions (1.00 QBEP, 0.82 QBEP, 0.74 QBEP, and 0.55 QBEP), considering five impeller rotational speeds (110 rpm, 130 rpm, 150 rpm, 170 rpm, and 190 rpm). Study results have shown that both PAT’s flow and pressure fields deteriorate with the machine influx decrease, where the impeller rotational speed increase is found to alleviate PAT pressure pulsation levels under high-flow operating conditions, while it worsens them under part-load conditions. This study’s results add value to a thorough understanding of PAT flow dynamics, which, in a long run, contributes to the solution of the so-far existent technical issues.

Measuring Congestion and Reliability Impacts of Safety Projects

2021 ◽  
pp. 036119812110067
Author(s):  
Simona Babiceanu ◽  
Sanhita Lahiri ◽  
Mena Lockwood
Keyword(s):  
Performance Measures ◽  
Positive Impact ◽  
Operating Conditions ◽  
Vehicle Miles Traveled ◽  
Data Set ◽  
Data Points ◽  
Practical Recommendations

This study uses a suite of performance measures that was developed by taking into consideration various aspects of congestion and reliability, to assess impacts of safety projects on congestion. Safety projects are necessary to help move Virginia’s roadways toward safer operation, but can contribute to congestion and unreliability during execution, and can affect operations after execution. However, safety projects are assessed primarily for safety improvements, not for congestion. This study identifies an appropriate suite of measures, and quantifies and compares the congestion and reliability impacts of safety projects on roadways for the periods before, during, and after project execution. The paper presents the performance measures, examines their sensitivity based on operating conditions, defines thresholds for congestion and reliability, and demonstrates the measures using a set of Virginia safety projects. The data set consists of 10 projects totalling 92 mi and more than 1M data points. The study found that, overall, safety projects tended to have a positive impact on congestion and reliability after completion, and the congestion variability measures were sensitive to the threshold of reliability. The study concludes with practical recommendations for primary measures that may be used to measure overall impacts of safety projects: percent vehicle miles traveled (VMT) reliable with a customized threshold for Virginia; percent VMT delayed; and time to travel 10 mi. However, caution should be used when applying the results directly to other situations, because of the limited number of projects used in the study.

scholarly journals Impact of environmental factors on growth and satratoxin G production by strains of Stachybotrys chartarum

2012 ◽  
Vol 5 (1) ◽  
pp. 37-43 ◽  
Author(s):  
S. Frazer ◽  
J. Pestka ◽  
J. Kim ◽  
A. Medina ◽  
D. Aldred ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Water Availability ◽  
Indoor Environment ◽  
Potato Dextrose Agar ◽  
Enzyme Linked Immunosorbent Assay ◽  
Stachybotrys Chartarum ◽  
Data Sets ◽  
Elisa Method ◽  
Contour Maps ◽  
First Time

The black mould Stachybotrys chartarum and its mycotoxins have been linked to damp building-associated illnesses. The objective of this study was to determine the effects of water availability (water activity, aw) and temperature on growth and production of satratoxin G (SG) by a macrocyclic trichothecene-producing strain (IBT 7711) and non-producing strain (IBT 1495) of S. chartarum. Growth studies were carried out on potato dextrose agar modified with glycerol to 0.995-0.92 aw at 10-37 °C. Growth extension was measured and the cultures were extracted after 10 days and a competitive enzyme-linked immunosorbent assay (ELISA) method used to quantify the SG content. Growth was optimal at 25 to 30 °C at 0.995 aw, but this was modified to 0.98 aw at 30 °C for both strains (1.4-1.6 mm/day, respectively). The ELISA method revealed that, in contrast to growth, SG production was maximal at 20 °C with highest production at 0.98 aw (approximately 250 μg/g mycelia). When water was freely available (0.995 aw), SG was maximally produced at 15 °C and decreased as temperature was increased. Interestingly, the strain classified as a non-toxigenic produced very low amounts of SG (<1.6 μg/g mycelia) that were maximal at 25 °C and 0.98 aw. Contour maps for growth and SG production were developed from these data sets. These data have shown, for the first time, that growth and SG production profiles are very different in relation to key environmental conditions in the indoor environment. This will be very useful in practically determining the risk from exposure to S. chartarum and its toxins in the built environment.

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