scholarly journals A TRAFFIC FUNDAMENTAL DIAGRAM CALIBRATING METHODOLOGY TO AVOID UNBALANCED SPEED–DENSITY OBSERVATIONS

Transport ◽  
2021 ◽  
Vol 36 (1) ◽  
pp. 13-24
Author(s):  
Chunbo Zhang ◽  
Zhaoguo Huang ◽  
Yonggang Wang
Keyword(s):  
Traffic Flow ◽  
Least Square Method ◽  
Least Square ◽  
Fundamental Diagram ◽  
Traffic Capacity ◽  
Density Relationship ◽  
Sample Method

Traffic fundamental diagram is extremely important to analyse traffic flow and traffic capacity, and the central part of traffic fundamental diagram is to calibrate speed–density relationship. However, because of unbalanced speed–density observations, calibrating results using Least Square Method (LSM) with all speed–density points always lead to inaccurate effect, so this paper proposed a selecting data sample method and then LSM was used to calibrate four well-known single-regime models. Comparisons were made among the results using LSM with all speed–density points and the selecting data sample. Results indicated that the selecting data sample method proposed by this paper can calibrate the singleregime models well, and the method overcomes the inaccurate effect caused by unbalanced speed–density observations. Data from different highways validated the results. The contribution of this paper is that the proposed method can help researchers to determine more precise traffic fundamental diagram.

scholarly journals Determination of Observation Weight to Calibrate Freeway Traffic Fundamental Diagram Using Weighted Least Square Method (WLSM)

2017 ◽  
Vol 29 (2) ◽  
pp. 203-212
Author(s):  
Chunbo Zhang ◽  
Xiucheng Guo ◽  
Zhenping Xi
Keyword(s):  
Least Square Method ◽  
Specific Weight ◽  
Interesting Case ◽  
Least Square ◽  
Observation Data ◽  
Fundamental Diagram ◽  
Freeway Traffic ◽  
Weighted Least Square ◽  
Density Relationship ◽  
The One

Due to unbalanced speed-density observations, the one-regime traffic fundamental diagram and speed-density relationship models using least square method (LSM) cannot reflect actual conditions under congested/jam traffic. In that case, it is inevitable to adopt the weighted least square method (WLSM). This paper used freeway Georgia State Route 400 observation data and proposed 5 weight determination methods except the LSM to analyse 5 wellknown one-regime speed-density models to determine the best calibrating models. The results indicated that different one-regime speed-density models have different best calibrating models, for Greenberg, it was possible to find a specific weight using LSM, which is similar for Underwood and Northwestern Models, but different for that one known as 3PL model. An interesting case is the Newell's Model which fits well with two distinct calibration weights. This paper can make contribution to calibrating a more precise traffic fundamental diagram.

Vessel Traffic Flow Distribution Model of Bridge Area Waterway in the Middle Stream of Yangtze River

2014 ◽  
Vol 551 ◽  
pp. 127-133 ◽  
Author(s):  
Hai Qiang Hou ◽  
Yi Cheng Li ◽  
Wei He ◽  
Xing Long Liu
Keyword(s):  
Traffic Flow ◽  
Yangtze River ◽  
Flow Distribution ◽  
Least Square Method ◽  
Least Square ◽  
Distribution Model ◽  
Distribution Rule ◽  
Operating Factor ◽  
Safety Operation ◽  
Vessel Speed

Traffic flow data collection in Wuhan Yangtze River Bridge, locates in the middle of Yangtze River, is help for analysis of the waterway operating factor, which in return increases the capacity in the bridge area waterways and promotes vessel collision avoidance. Traffic flow parameters like vessel speed, arrival time, vessel clearance were collected by manual observation. Through analysis of vessel speed and vessel clearance distribution rule, the vessel speed-clearance model is established based on least square method. Real-time density of ships on navigation, channel utilization and ship safety operation area can be obtained by study on the relationship between speed and shipping space..

Novel Approach for Calibrating Freeway Highway Multi-Regimes Fundamental Diagram

2020 ◽  
Vol 2674 (9) ◽  
pp. 561-574
Author(s):  
Emmanuel Kidando ◽  
Alican Karaer ◽  
Boniphace Kutela ◽  
Angela E. Kitali ◽  
Ren Moses ◽  
...  
Keyword(s):  
Traffic Flow ◽  
Bayesian Model ◽  
Potential Benefit ◽  
Data Driven ◽  
Fundamental Diagram ◽  
Novel Approach ◽  
Proposed Model ◽  
Density Relationship ◽  
Data Driven Approach ◽  
Flow Variables

For almost a century, several models have been developed to calibrate the pairwise relationship between traffic flow variables, that is, speed, density, and flow. Multi-regime models are well known for being superior over single-regime models in fitting the speed–density relationship. However, in modeling multi-regime models, breakpoints that separate the regimes are visually established based on the subjective judgment of data characteristics. Thus, this study proposes a data-driven approach to estimate the breakpoints of multi-regime models. It applies the Bayesian model for calibrating multi-regime models (two and three-regime models) for fitting traffic flow fundamental diagram. Furthermore, the analysis presented accounts for the random characteristics associated with the flow. To demonstrate the application of the proposed algorithm, traffic flow data from Interstate 10 (I-10) freeway in Jacksonville, Florida, were used in the analysis. The results demonstrate the potential benefit of using the proposed model in calibrating the fundamental diagram. The proposed approach can also quantify uncertainty and encode prior knowledge about the breakpoints in the model if the model developer wishes.

Construction of Adjustment Model of Traffic Volume Forecast in The Latter Part of Expressway Operating

2012 ◽  
Vol 178-181 ◽  
pp. 1526-1531
Author(s):  
Ming Shun Li ◽  
Zuo Hui Zhu
Keyword(s):  
Linear Relationship ◽  
Traffic Flow ◽  
Feasibility Study ◽  
Least Square Method ◽  
Traffic Volume ◽  
Least Square ◽  
Adjustment Model ◽  
Traffic Flow Forecast ◽  
Method Model ◽  
Flow Forecast

This paper focuses on the problem of serious deviation about predicted traffic flow on the feasibility study stage of expressway,puts forward an idea to compare and analyse the predicted traffic flow in feasibility study stage and the actual traffic after project operation,introducts least square method model, and finds out the linear relationship between them, thus predicts traffic flow of expressway operation. Finally, the calculation is made by combining with concrete expressway project,which proves that this method is usefull to improving the accuracy of the traffic flow forecast.

Direct Assessment of Effective Renal Plasma Flow from Renoscintigraphy with a Gamma Camera and an On-Line Computer

1981 ◽  
Vol 20 (06) ◽  
pp. 274-278
Author(s):  
J. Liniecki ◽  
J. Bialobrzeski ◽  
Ewa Mlodkowska ◽  
M. J. Surma
Keyword(s):  
Count Rate ◽  
Renal Plasma Flow ◽  
Early Period ◽  
Least Square Method ◽  
Least Square ◽  
Uptake Coefficient ◽  
Positive Linear Correlation ◽  
On Line ◽  
Best Fit ◽  
Plasma Activity

A concept of a kidney uptake coefficient (UC) of 131I-o-hippurate was developed by analogy from the corresponding kidney clearance of blood plasma in the early period after injection of the hippurate. The UC for each kidney was defined as the count-rate over its ROI at a time shorter than the peak in the renoscintigraphic curve divided by the integral of the count-rate curve over the "blood"-ROI. A procedure for normalization of both curves against each other was also developed. The total kidney clearance of the hippurate was determined from the function of plasma activity concentration vs. time after a single injection; the determinations were made at 5, 10, 15, 20, 30, 45, 60, 75 and 90 min after intravenous administration of 131I-o-hippurate and the best-fit curve was obtained by means of the least-square method. When the UC was related to the absolute value of the clearance a positive linear correlation was found (r = 0.922, ρ > 0.99). Using this regression equation the clearance could be estimated in reverse from the uptake coefficient calculated solely on the basis of the renoscintigraphic curves without blood sampling. The errors of the estimate are compatible with the requirement of a fast appraisal of renal function for purposes of clinical diagknosis.

PENGARUH KNOWLEDGE MANAGEMENT, KOMPETENSI, MOTIVASI TERHADAP KINERJA KARYAWAN

2015 ◽  
Vol 5 (2) ◽  
pp. 1
Author(s):  
Miftahol Arifin
Keyword(s):  
Knowledge Management ◽  
Linear Regression ◽  
Significant Influence ◽  
Employee Performance ◽  
Least Square Method ◽  
Least Square ◽  
Analysis Tool ◽  
Ordinary Least Square ◽  
Competence Motivation ◽  
Performance Analyze

The purpose of this research is to analyze the influence of knowledge management on employee performance, analyze the effect of competence on employee performance, analyze the influence of motivation on employee performance). In this study, samples taken are structural employees PT.centris Kingdom Taxi Yogyakarta. The analysis tool in this study using multiple linear regression with Ordinary Least Square method (OLS). The conclusion of this study showed that the variables of knowledge management has a significant influence on employee performance, competence variables have an influence on employee performance, motivation variables have an influence on employee performance, The analysis showed that the variables of knowledge management, competence, motivation on employee performance.Keywords: knowledge management, competence, motivation, employee performance.

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