Level-of-Service Model for Pedestrians at Signalized Intersections

2005 ◽  
Vol 1939 (1) ◽  
pp. 54-62 ◽  
Author(s):  
Theodore A. Petritsch ◽  
Bruce W. Landis ◽  
Peyton S. McLeod ◽  
Herman F. Huang ◽  
Srikalyan Challa ◽  
...  
Keyword(s):  
Motor Vehicle ◽  
Pearson Correlation ◽  
The United States ◽  
Signalized Intersections ◽  
Level Of Service ◽  
Science Field ◽  
Perceived Safety ◽  
Operational Characteristics ◽  
Field Data Collection ◽  
Time Perceptions

This paper documents a study performed to develop a level-of-service (LOS) model that accurately represents pedestrians’ perceptions of crossings at signalized intersections. This model incorporates perceived safety and comfort (i.e., perceived exposure and conflicts) and operations (i.e., delay and signalization). Data for the model were obtained from an innovative Walk for Science field data collection event and video simulations. The data consist of ( a) participants’ perceptions of safety, comfort, and operations as they walk through selected signalized intersections and ( b) the design and operational characteristics of these intersections. The resulting model provides a measure of the pedestrian's perspective on how well an intersection's geometric and operational characteristics meets his or her needs. The pedestrian LOS model for intersections described in this paper is based on Pearson correlation analyses and stepwise regression modeling of approximately 800 combined real-time perceptions (observations) from pedestrians walking a course through signalized intersections in a typical U.S. metropolitan area. The resulting general model for the pedestrian LOS at intersections is highly reliable, has a high correlation coefficient ( R2 = .73) with the average observations, and is transferable to the majority of metropolitan areas in the United States. Primary factors in the pedestrian LOS model for intersections include right-turn-on-red volumes for the street being crossed, permissive left turns from the street parallel to the crosswalk motor vehicle volume on the street being crossed, midblock 85th percentile speed of the vehicles on the street being crossed, number of lanes being crossed, pedestrian's delay, and presence or absence of right-turn channelization islands.

scholarly journals Method to Determine Pedestrian Level of Service for the Overall Unsignalized Midblock Crossings of Road Segments

2014 ◽  
Vol 6 ◽  
pp. 652986 ◽  
Author(s):  
Lin Zhao ◽  
Yang Bian ◽  
Jian Lu ◽  
Jian Rong
Keyword(s):  
Urban Areas ◽  
Motor Vehicle ◽  
Pearson Correlation ◽  
Level Of Service ◽  
Perception Of Safety ◽  
Operational Characteristics ◽  
Traffic Conflicts ◽  
Pedestrian Level Of Service ◽  
Broad Cross Section ◽  
Road Segments

This paper aims at developing a pedestrian level of service (LOS) model for the overall unsignalized midblock crossings of road segments from the perspective of the pedestrian's perception of safety and convenience in Chinese midblock crossing environment. Firstly, the potential primary factors influencing pedestrian LOS at unsignalized midblock crosswalks were summarized from four respects: traffic conflicts, the distance between crosswalks, crossing facilities, and delay. Secondly, 948 participants’ real-time sense of safety and convenience when they were crossing the 30 selected unsignalized midblock crosswalks and the design and operational characteristics of the selected road segments were collected. The selected midblock crosswalks were typical of those prevalent in the medium-sized urban areas of China, and the participants of questionnaire survey covered a broad cross section of Chinese population of pedestrians. Finally, Pearson correlation analysis and stepwise regression analysis were carried out to develop pedestrian LOS model for the overall unsignalized midblock crossings of road segments. The results revealed that the factors significantly influencing pedestrian LOS of the overall unsignalized midblock crossings of road segments included volume of two-way motor vehicle, the distance between marked midblock crosswalks, and the distance between unmarked crosswalks. A reliable, statistically calibrated pedestrian LOS model was developed ( R2 = 0.80).

Intersection Level of Service for the Bicycle Through Movement

2003 ◽  
Vol 1828 (1) ◽  
pp. 101-106 ◽  
Author(s):  
Bruce W. Landis ◽  
Venkat R. Vattikuti ◽  
Russell M. Ottenberg ◽  
Theodore A. Petritsch ◽  
Martin Guttenplan ◽  
...  
Keyword(s):  
Transportation Network ◽  
Pearson Correlation ◽  
Geographic Origin ◽  
Level Of Service ◽  
Total Width ◽  
Department Of Transportation ◽  
Service Model ◽  
Florida Department ◽  
Bicycle Level Of Service ◽  
Time Perceptions

The Florida Department of Transportation (DOT) has initiated multi-modal level-of-service (LOS) methodologies, including that for the bicycle travel mode. It has already adopted a bicycle LOS methodology for the roadway segment portion of the transportation network, the Bicycle Level of Service Model. Florida DOT’s ultimate goal is to develop corridor- and facilities-level LOS methodologies. Toward that goal, Florida DOT sponsored research to develop the first part of an intersection bicycle LOS methodology, the Intersection LOS for the bicycle through movement. This Intersection LOS for the bicycle through movement would provide a measure of the level of safety and comfort experienced by bicyclists riding through an intersection. The Intersection LOS model for the bicycle through movement is based on Pearson correlation analyses and stepwise regression modeling of approximately 1,000 combined real-time perceptions from bicyclists traveling a course through a typical U.S. metropolitan area’s signalized intersections. The study’s participants represented a cross section of age, gender, and geographic origin of the population of cyclists. Although further hypothesis testing is being conducted, the resulting general model for the Intersection LOS for the bicycle through movement is highly reliable, has a high correlation coefficient ( R2 = 0.83) with the average observations, and is transferable to the vast majority of U.S. metropolitan areas. The study reveals that roadway traffic volume, total width of the outside through lane, and the intersection (cross street) crossing distance are primary factors in the Intersection LOS for the bicycle through movement.

Method to Determine Pedestrians Level of Service for Unsignalized Intersections

2012 ◽  
Vol 253-255 ◽  
pp. 1936-1943 ◽  
Author(s):  
Yang Bian ◽  
Lu Jian ◽  
Lin Zhao
Keyword(s):  
Urban Areas ◽  
Chinese Population ◽  
Pearson Correlation ◽  
Level Of Service ◽  
Unsignalized Intersections ◽  
Factors Influencing ◽  
Operational Characteristics ◽  
Traffic Conflicts ◽  
Pearson Correlation Analysis ◽  
Broad Cross Section

This paper aims at developing a Level of Service (LOS) model for unsignalized intersection crosswalks for pedestrians from the perspective of the pedestrian’s perception of comfort and safety in unsignalized intersection environment. Firstly, the potential primary factors influencing pedestrian LOS at crosswalk were summarized from three respects: traffic conflicts, crossing facilities and delay. Secondly, data for the model were collected, including 459 participants’ real-time sense of comfort and safety when they crossing the 11 selected intersection crosswalks and the design and operational characteristics of the selected intersections. The selected crosswalks were typical of those prevalent in the urban areas of China, and the participants of questionnaire survey covered a broad cross section of Chinese population of pedestrians. Based on the survey data, Pearson Correlation analysis and step-wise regression analysis were carried out to develop pedestrian LOS model for unsignalized intersections. A reliable, statistically calibrated pedestrian LOS model for unsignalized intersections was developed, suitable for application in the vast majority of Chinese urban areas. The study revealed that the factors significantly influencing pedestrian LOS at unsignalized intersections included: left turning bicycles from side streets, through bicycles from side streets, right turning bicycles from side streets, left turning bicycles approaching from the street parallel to the crosswalk, through bicycles from the approach opposite to the crosswalk, right turning bicycles from the street parallel to the crosswalk, through bicycles from the approach opposite to the crosswalk and the presence of the median.

scholarly journals Pedestrian perception-based level-of-service model at signalized intersection crosswalks

2019 ◽  
Vol 27 (4) ◽  
pp. 266-281
Author(s):  
S. Marisamynathan ◽  
P. Vedagiri
Keyword(s):  
Pearson Correlation ◽  
Linear Regression Analysis ◽  
Regression Method ◽  
Signalized Intersections ◽  
Level Of Service ◽  
Threshold Values ◽  
User Perception ◽  
Perception Of Safety ◽  
Measure Of Performance ◽  
Conventional Regression

Abstract Pedestrian level of service (PLOS) is an important measure of performance in the analysis of existing pedestrian crosswalk conditions. Many researchers have developed PLOS models based on pedestrian delay, turning vehicle effect, etc., using the conventional regression method. However, these factors may not effectively reflect the pedestrians’ perception of safety while crossing the crosswalk. The conventional regression method has failed to estimate accurate PLOS because of the primary assumption of an arbitrary probability distribution and vagueness in the input data. Moreover, PLOS categories in existing studies are based on rigid threshold values and the boundaries that are not well defined. Therefore, it is an important attempt to develop a PLOS model with respect to pedestrian safety, convenience, and efficiency at signalized intersections. For this purpose, a video-graphic and user perception surveys were conducted at selected nine signalized intersections in Mumbai, India. The data such as pedestrian, traffic, and geometric characteristics were extracted, and significant variables were identified using Pearson correlation analysis. A consistent and statistically calibrated PLOS model was developed using fuzzy linear regression analysis. PLOS was categorized into six levels (A–F) based on the predicted user perception score, and threshold values for each level were estimated using the fuzzy c-means clustering technique. The developed PLOS model and threshold values were validated with the field-observed data. Statistical performance tests were conducted and the results provided more accurate and reliable solutions. In conclusion, this study provides a feasible alternative to measure pedestrian perception-based level of service at signalized intersections. The developed PLOS model and threshold values would be useful for planning and designing pedestrian facilities and also in evaluating and improving the existing conditions of pedestrian facilities at signalized intersections.

scholarly journals Examining concurrent validity between COMLEX-USA Level 2-Cognitive Evaluation and COMLEX-USA Level 2-Performance Evaluation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Brandon Craig ◽  
Xiaolin Wang ◽  
Jeanne Sandella ◽  
Tsung-Hsun Tsai ◽  
David Kuo ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Concurrent Validity ◽  
Pearson Correlation ◽  
The United States ◽  
National Board ◽  
Cognitive Evaluation ◽  
Competency Domain ◽  
Medical Examiners ◽  
Pearson Correlations ◽  
Level 2

Abstract Context The Comprehensive Osteopathic Medical Licensing Examination of the United States of America (COMLEX-USA) is a three level examination used as a pathway to licensure for students in osteopathic medical education programs. COMLEX-USA Level 2 includes a written assessment of Fundamental Clinical Sciences for Osteopathic Medical Practice (Level 2-Cognitive Evaluation [L2-CE]) delivered in a computer based format and separate performance evaluation (Level 2-Performance Evaluation [L2-PE]) administered through live encounters with standardized patients. L2-PE was designed to augment L2-CE. It is expected that the two examinations measure related yet distinct constructs. Objectives To explore the concurrent validity of L2-CE with L2-PE. Methods First attempt test scores were obtained from the National Board of Osteopathic Medical Examiners database for 6,639 candidates who took L2-CE between June 2019 and May 2020 and matched to the students’ L2-PE scores. The sample represented all colleges of osteopathic medicine and 97.5% of candidates who took L2-CE during the complete 2019–2020 test cycle. We calculated disattenuated correlations between the total score for L2-CE, the L2-CE scores for the seven competency domains (CD1 through CD7), and the L2-PE scores for the Humanistic Domain (HM) and Biomedical/Biomechanical Domain (BM). All scores were on continuous scales. Results Pearson correlations ranged from 0.10 to 0.88 and were all statically significant (p<0.01). L2-CE total score was most strongly correlated with CD2 (0.88) and CD3 (0.85). Pearson correlations between the L2-CE competency domain subscores ranged from 0.17 to 0.70, and correlations which included either HM or BM ranged from 0.10 to 0.34 with the strongest of those correlations being between BM and L2-CE total score (0.34) as well as between HM and BM (0.28).The largest increase between corresponding Pearson and disattenuated correlations was for pairs of scores with lower reliabilities such as CD5 and CD6, which had a Pearson correlation of 0.17 and a disattenuated correlation of 0.68. The smallest increase in correlations was observed in pairs of scores with larger reliabilities such as L2-CE total score and HM, which had a Pearson correlation of 0.23 and a disattenuated correlation of 0.28. The reliability of L2-CE was 0.87, 0.81 for HM, and 0.73 for BM. The reliabilities for the L2-CE competency domain scores ranged from 0.22 to 0.74. The small to moderate correlations between the L2-CE total score and the two L2-PE support the expectation that these examinations measure related but distinct constructs. The correlations between L2-PE and L2-CE competency domain subscores reflect the distribution of items defined by the L2-PE blueprint, providing evidence that the examinations are performing as designed. Conclusions This study provides evidence supporting the validity of the blueprints for constructing COMLEX-USA Levels 2-CE and 2-PE examinations in concert with the purpose and nature of the examinations.

scholarly journals Personal Watercraft Incident Court Decisions: The Plaintiff’s Odds?

2021 ◽  
Vol 13 (9) ◽  
pp. 5096
Author(s):  
Eui-Yul Choi ◽  
Woo Jeong Cho
Keyword(s):  
Motor Vehicle ◽  
The United States ◽  
Insurance Companies ◽  
Court Decisions ◽  
Regression Analyses ◽  
Demographic Information ◽  
Slowing Down ◽  
Personal Watercraft ◽  
Successful Adults ◽  
Significant Factors

A personal watercraft (PWC) is a vessel that uses an inboard motor powering a water jet pump as a source of power and is operated by a person sitting, standing, or kneeling. Maneuvering a PWC is different from operating a motor vehicle or boat. An obstacle cannot be avoided by slowing down and turning the watercraft; throttle power is required to turn or maneuver the PWC. The watercraft stops only by drifting or turning sharply. The study examined sixty court decisions published in LexisNexis databases of the United States over the last decade. Cases included individuals injured while operating a PWC as a driver, passenger, or as a result of contact with a watercraft. A content analysis identified items to be used in the study. Crosstab and logistic regression analyses were used to identify demographic information and the characteristics of those who succeeded in a court of law. One-third of the cases were successful; adults, males, and the party who sustained a severe injury were more successful in a court of law with the exception of the statistically significant factors (high risk maneuvers and sharp turns). Among the additional results, we should be aware that insurance companies may not pay; additionally, it is unwise to loan a PWC to a female who has no experience.

scholarly journals Towards Including Dynamic Vegetation Parameters in the EUMETSAT H SAF ASCAT Soil Moisture Products

2021 ◽  
Vol 13 (8) ◽  
pp. 1463
Author(s):  
Susan C. Steele-Dunne ◽  
Sebastian Hahn ◽  
Wolfgang Wagner ◽  
Mariette Vreugdenhil
Keyword(s):  
Soil Moisture ◽  
Interannual Variability ◽  
Incidence Angle ◽  
Pearson Correlation ◽  
The United States ◽  
Research Network ◽  
Window Width ◽  
High Frequency Variability ◽  
Vegetation Parameters ◽  
The Impact

The TU Wien Soil Moisture Retrieval (TUW SMR) approach is used to produce several operational soil moisture products from the Advanced Scatterometer (ASCAT) on the Metop series of satellites as part of the EUMETSAT Satellite Application Facility on Support to Operational Hydrology and Water Management (H SAF). The incidence angle dependence of backscatter is described by a second-order Taylor polynomial, the coefficients of which are used to normalize ASCAT observations to the reference incidence angle of 40∘ and for correcting vegetation effects. Recently, a kernel smoother was developed to estimate the coefficients dynamically, in order to account for interannual variability. In this study, we used the kernel smoother for estimating these coefficients, where we distinguished for the first time between their two uses, meaning that we used a short and fixed window width for the backscatter normalisation while we tested different window widths for optimizing the vegetation correction. In particular, we investigated the impact of using the dynamic vegetation parameters on soil moisture retrieval. We compared soil moisture retrievals based on the dynamic vegetation parameters to those estimated using the current operational approach by examining their agreement, in terms of the Pearson correlation coefficient, unbiased RMSE and bias with respect to in situ soil moisture. Data from the United States Climate Research Network were used to study the influence of climate class and land cover type on performance. The sensitivity to the kernel smoother half-width was also investigated. Results show that estimating the vegetation parameters with the kernel smoother can yield an improvement when there is interannual variability in vegetation due to a trend or a change in the amplitude or timing of the seasonal cycle. However, using the kernel smoother introduces high-frequency variability in the dynamic vegetation parameters, particularly for shorter kernel half-widths.

Finite Element Based Injury Metrics for Pulmonary Contusion From Vehicle to Vehicle Crash Simulations

2012 ◽  
Author(s):  
Kerry A. Danelson ◽  
Joel D. Stitzel
Keyword(s):  
Distress Syndrome ◽  
Motor Vehicle ◽  
Public Health Problem ◽  
The United States ◽  
Pulmonary Contusion ◽  
Volumetric Measurement ◽  
Abbreviated Injury Scale ◽  
Sampling System ◽  
Vehicle To Vehicle ◽  
Injured Lung

Motor Vehicle Crashes (MVCs) are a public health problem in the United States. In 2009, 33,808 Americans were killed in a MVC and 2.22 million more were injured.4 Pulmonary contusion (PC) is a common injury following MVC with over 38% of the Abbreviated Injury Scale (AIS) 3+ thoracic injuries identified as some form of PC in a recent National Automotive Sampling System (NASS) study.5 Miller et al. correlated the percent injured lung to the possibility of developing Acute Respiratory Distress Syndrome (ARDS). The results indicated that if 20% of the lung was injured, the incidence of ARDS sharply increased with seventy-eight percent of those patients developing ARDS.2 The significance of these findings is that the volumetric measurement of PC can predict possible clinical outcomes.

Depression and Inflammatory Markers in Veterans With Multiple Sclerosis

2021 ◽  
pp. 109980042110500
Author(s):  
Pamela Newland ◽  
Yelyzaveta Basan ◽  
Ling Chen ◽  
Gregory Wu
Keyword(s):  
Multiple Sclerosis ◽  
Inflammatory Markers ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
The United States ◽  
Biological Mechanisms ◽  
The Central Nervous System ◽  
Brain And Spinal Cord ◽  
The Brain

Multiple sclerosis (MS), an inflammatory neurodegenerative disease of the central nervous system (CNS), afflicts over one per thousand people in the United States. The pathology of MS typically involves lesions in several regions, including the brain and spinal cord. The manifestation of MS is variable and carries great potential to negatively impact quality of life (QOL). Evidence that inflammatory markers are related to depression in MS is accumulating. However, there are barriers in precisely identifying the biological mechanisms underlying depression and inflammation. Analysis of cytokines provides one promising approach for understanding the mechanisms that may contribute to MS symptoms. Methods: In this pilot study, we measured salivary levels of interleukin (IL)-6, IL-1beta (β), and IL-10 in 24 veterans with MS. Descriptive statistics were reported and Pearson correlation coefficients were obtained between cytokines and depression. Results: The anti-inflammatory cytokine IL-10 was significantly negatively associated with depression in veterans with MS (r = −0.47, p = .024). Conclusion: Cytokines may be useful for elucidating biological mechanisms associated with the depression and a measure for nurses caring for veterans with MS.

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