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Britton Hammit, Kimley-Horn Jiaxin Tong, Kimley-Horn ... · PDF file Britton Hammit, Kimley-Horn. Jiaxin Tong, Kimley-Horn. Sanhita Lahiri, VDOT. VDOT VISSIM User Guide 2020 SimCap

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  • Britton Hammit, Kimley-Horn Jiaxin Tong, Kimley-Horn Sanhita Lahiri, VDOT

    VDOT VISSIM User Guide

    2020 SimCap Meeting

    January 14, 2020

  • Outline

    • Introduction

    • Overview of Contents

    • Vissim 11 Evaluation

    • Calibration Guidance

    • Conclusions

    2

  • Purpose and Need • Supplement VDOT Traffic Operations and Safety

    Analysis Manual (TOSAM).

    • Provide guidance and Virginia best practices for model development and analysis.

    • Maintain consistency for peer and agency review.

    • Promote the quality and consistent VISSIM analysis in support of decision making for project planning and infrastructure.

    3

  • User Guide Contents • Model Development

    • Model Review and Debugging • QC Checklist

    • Results and Preparation

    • Calibration Guidance

    • Model Scenarios

    4

  • Vissim 11 Evaluation

    5

  • Vissim 11 Evaluation Objectives • Improve understanding of Vissim 11 to

    provide VDOT recommendation on its adoption for new projects.

    • Provide guidelines for running legacy models in Vissim 11.

    • Highlight differences in parameter sensitivities between Vissim 11 and legacy software versions.

    • Update existing Vissim calibration guidance. 6

  • Questions of Interest 1. Will Vissim models calibrated in legacy

    Vissim versions remain calibrated when run directly in Vissim 11?

    2. Do these driving behavior model changes elicit a change in calibration guidance for specific parameters?

    7

  • Legacy Vissim Models • Compare the results of previously calibrated

    models in prior versions of Vissim with the results obtained by running those models in Vissim 11.

    • 10 Calibrated Models (5 Networks, AM/PM) • Models selected with varying network sizes,

    network features, and operational conditions.

    8

  • Legacy Vissim Models

    9

    Name Maintained Calibration in Vissim 11

    Primary MOE Difference between

    Versions

    Severity of MOE Difference

    Route 7 AM No Queue Length Moderate

    Route 7 PM No Travel Times Substantial

    Route 28 AM Yes - -

    Route 28 PM No Freeway speeds Substantial

    Seminary Road AM No Freeway speeds Substantial

    Seminary Road PM Yes Freeway speeds Moderate

    I-95 AM Yes - -

    I-95 PM No Speed Criteria Moderate

    Route 123 AM No Travel Times Substantial

    Route 123 PM No Travel Times Substantial

  • Potential Causes • Unique traffic conditions

    • Model development

    • Model calibration

    10

    Model Development

    AM Model Calibration

    PM Model Calibration

  • Calibration

    11

  • Calibration Adjust these:

    12

  • Calibration Using these:

    13

    Freeway Car Following Model (Wiedemann 99) – Calibration Parameters

    Parameter Default Value Unit Suggested Range

    Basic Segment

    Weave/Merge/ Diverge Segment

    CC0 Standstill distance 4.92 feet (ft) 4.5 to 5.5 >4.92

    CC1 Headway time 0.9 seconds (s) 0.85 to 1.05 0.90 to 1.50

    CC2 ‘Following’ variation 13.12 ft 6.56 to 22.97 13.12 to 39.37

    CC3 Threshold for entering ‘following’ -8 -- Use default

    CC4 Negative ‘following’ threshold -0.35 -- Use default

    CC5 Positive ‘following’ threshold 0.35 -- Use default

    CC6 Speed dependency of oscillation 11.44 -- Use default

    CC7 Oscillation acceleration 0.82 ft/s2 Use default

    CC8 Standstill acceleration 11.48 ft/s2 Use default

    CC9 Acceleration at 50 mph 4.92 ft/s2 Use default

    Arterial Car Following Model (Wiedemann 74) – Calibration Parameters

    Parameter Default Value Unit Suggested

    Range

    Average standstill distance 6.56 feet (ft) 3.28 to 6.56

    Additive part of safety distance 2.00 -- 2.0 to 2.2

    Multiplicative part of safety distance 3.00 -- 2.8 to 3.3

  • Calibration To reach these:

    14

  • Calibration Styles

    15

    Calibration Styles

  • Differences in Calibration Style

    • Activation of the Cooperative Lane Change parameter at merge, diverge, and weaving segments.

    • A low Safety Distance Reduction Factor.

    • Activation of the Advanced Merge parameter.

    16

  • Cooperative Lane Change

    17

    Cooperative Lane Change

    Activated

    Calibrated

    Route 28 AM

    I-95 AM

    Not Activated

    Uncalibrated

    Route 28 PM

    I-95 PM

  • Cooperative Lane Change

    18

    Route 28, AM Model CLC Activated - Calibrated

    Field Vissim 9 Vissim 11 Field Vissim 9 Vissim 11

    Route 28, PM Model CLC not Activated – Not Calibrated

  • Safety Distance Reduction Factor

    19

    Safety Distance Reduction Factor (SDRF)

    0.25

    Uncalibrated

    Seminary Road AM

    Route 123 AM

    Route 123 PM

    0.55

    Calibrated

    Seminary Road PM

  • Safety Distance Reduction Factor

    20

    Seminary Road, PM Model SDRF Near Default – Calibrated

    Field Vissim 9 Vissim 11

    Field Vissim 9 Vissim 11

    Seminary Road, AM Model SDRF Significantly Below Default

    – Not Calibrated

  • Advanced Merge

    21

    Advanced Merge

    Activated

    Calibrated

    Route 28 AM

    Seminary Road PM

    I-95 AM

    Not Activated

    Uncalibrated

    Route 28 PM

    Seminary Road AM

    I-95 PM

  • Summary • Models that were previously calibrated in legacy

    versions of Vissim were more likely to maintain calibration in Vissim 11 when

    • Cooperative Lane Change and Advanced Merge features were activated.

    • Safety Distance Reduction factor was maintained at a conservative value near default.

    • When converting a calibrated legacy model to Vissim 11, time and resources should be allotted to re-visit model calibration and fully QC model operations.

    22

  • Questions of Interest 1. Will Vissim models calibrated in legacy

    Vissim versions remain calibrated when run directly in Vissim 11?

    2. Do these driving behavior model changes elicit a change in calibration guidance for specific parameters?

    23

  • Calibration Parameter Evaluation • Sensitivity analysis of parameters in Vissim 9

    and 11 to study the impact of changes in parameter values on model outputs

    24

    5 Models

    17 Parameters

    4 Parameter Values

  • Summary of Findings • Updates to lane change algorithms in Vissim 11

    should yield smoother traffic flow under the default parameter settings.

    • Thus, modelers should need to make fewer changes towards a more “aggressive” driving behavior settings.

    • Safety Distance Reduction Factor • Lane Change Distance

    • No evidence that previously-established recommendations for parameter ranges need to be revised.

    25

  • Findings  Practical Guidance Evidence that some “Calibration Styles” are preferred over others.

    • Narrowing ambiguity in the calibration process. • Improving resulting model robustness,

    transferability, and consistency.

    26

  • Calibration Guidance

    • Calibration parameter definitions • Calibration plan • Pre-Calibration set-up • Calibration guidelines • Calibration steps and structure

    27

  • Calibration Guidelines 1. Activate cooperative lane change at all merge,

    diverge, weaving segments.

    2. Keep freeway car-following model parameters CC0 and CC1 consistent between all connected freeway links.

    3. Freeway car-following model parameter CC2 should be greater in merge, diverge, weaving segments compared to basic segments.

    4. Safety Distance Reduction Factor adjustment should be a last resort in model calibration.

    28

  • CC1 Consistency

    29

    CC1 = 0.9 sec

    CC1 = 1.1 sec

    CC1 = 1.2 sec

  • 30

  • 31

    Round 1 Iterative adjustments of: • CCO/CC1 • CC2 for “basic segments” • CC2 for “merge, diverge, and weaving segments” • Lane Change Distance

    Round 2 Iterative adjustments of: • Additional seeding conditions • Lane change deceleration parameters • Cooperative Lane Change parameters • Minimum Net Headway lane change parameter

    Round 3 Iterative adjustments of: • Addition of special Driving Behavior Containers • Safety Distance Reduction Factor lane change parameter

    Freeway Corridor Calibration

    Only if necessary

  • Summary

    32

    • Model calibration will always be an iterative, trial-and-error procedure with numerous uncertainties.

    • VDOT’s user guide introduces new guidelines and steps that can be used to structure this iterative procedure to improve consistency, efficiency, and model validity.

    VISSIM User Guide is available at http://www.virginiadot.org/business/resources/VDOT_Vissim_UserGui

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