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Project Presentation For ECIV 748 – Traffic Flow Theory ESTIMATING PARAMETERS FOR

Project Presentation For ECIV 748 – Traffic Flow Theory ESTIMATING PARAMETERS FOR MODIFIED GREENSHIELD’S MODEL FROM FIELD OBSERVATIONS Omor Sharif Fall 2010 University of South Carolina, Columbia. Topics. 1. Background and Objective 2. Data Extraction 3. Data Visualization

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Project Presentation For ECIV 748 – Traffic Flow Theory ESTIMATING PARAMETERS FOR

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  1. Project Presentation For ECIV 748 – Traffic Flow Theory ESTIMATING PARAMETERS FOR MODIFIED GREENSHIELD’S MODEL FROM FIELD OBSERVATIONS Omor Sharif Fall 2010 University of South Carolina, Columbia

  2. Topics 1. Background and Objective 2. Data Extraction 3. Data Visualization 4. Parameter Estimation of Modified’ Greenshield’s Model 5. Findings and Conclusions

  3. Background and Project Objective To associate theoretical traffic models with field observations of traffic flow • Greenshield’sModel (1934) – Linear Speed-Density Model • Modified Greenshield’sModel – To improve upon limitations of original model • Two Regime Model adopted in this project– • Estimating parameters for • Constant Speed Model (Free flow Regime) • Modified Greenshield’s Model (Congested Regime )

  4. Data Extraction Source - Online Database Repositories GPS-enabled vehicles and mobile devices, traditional road sensors, fixed point sensors and GPS probes Two Sources - INRIX.com TRAFFIC.com Dataset available from TRAFFIC.com

  5. Data Visualization- Macroscopic Flow Characteristics (@Hammond Road) FIGURE Hourly flow patterns for different days in EB direction FIGURE Hourly flow patterns for different days in WB direction

  6. Data Visualization- Macroscopic Flow Characteristics (@Hammond Road) • FIGURE Directional Split on Thursday • FIGURE Average hourly distribution of mode in the study period

  7. Data Visualization- Macroscopic Speed Characteristics (@Hammond Road) • FIGURE Hourly speed distributions • with standard deviation (WB) • FIGURE Speed histogram from four week speed data (EB)

  8. Estimating Parameters • Greenshield’s model: Two Regime Model: Modified Greenshield’s model:

  9. Parameters for I-40 @ Hammond Road

  10. Parameters for I-40 @ Harrison Avenue

  11. Parameters for I-40 @ Davis Drive

  12. Closing Remarks • Two regime model is preferable instead of a single regime • Constant speed model for free flow region and Modified Greenshield’s model for congested flow region was adopted • The fit is better for Hammond road and Davis drive compared to Harrison avenue • The free flow speed is lower than speed limit for all three sections • Mode overestimates Jam density for Hammond Road and Davis drive (reaches maximum possible physical density) • At a density greater than 40 pce/mile/lane all sections reaches capacity and become congested at higher density • Very few observations at capacity and poor tracking of near capacity observations by the model • Overall The proposed two regime model tracks the field data reasonably well

  13. Thank YouQuestions ?

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