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Microsimulation for Rural and Exurban Regions: Lake County, California David Gerstle (presenting) & Zheng Wei Caliper Corporation
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Executive Summary Microsimulation is an important tool for modeling exurban and rural areas Congestion is often not an important driver of travel times “Minutia” such as grade, curvature, and lane widths are vitally important Shown using a case-study of Lake County, California using Caliper’s TransModeler microsimulation software: –Show how we calibrated & validated the model –Show failure to validate absent grade, curvature, lane widths, etc.
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Outline Project Background Model Scope Model Preparation Model Minutia
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Outline Project Background Model Scope Model Preparation Model Minutia
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Project Background Lake County Area Microsimulation Model (LAMM) To develop a traffic simulation model that: –Supports planning and operational analysis –Focuses on SR-20, SR-53, and SR-29 and the communities surrounding Clear Lake –Extends and complements existing models and modeling activities To evaluate future-year scenarios
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Project Background Lake County Area Microsimulation Model (LAMM) To develop a traffic simulation model that: –Supports planning and operational analysis –Focuses on SR-20, SR-53, and SR-29 and the communities surrounding Clear Lake –Extends and complements existing models and modeling activities To evaluate future-year scenarios
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Approx. 2 hr. drive from SFO to southern Lake County
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Lake County
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Project Background Lake County Area Microsimulation Model (LAMM) To develop a traffic simulation model that: –Supports planning and operational analysis –Focuses on SR-20, SR-53, and SR-29 and the communities surrounding Clear Lake –Extends and complements existing models and modeling activities To evaluate future-year scenarios
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Dominant route for through traffic passes through populated areas
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Outline Project Background Model Scope Model Preparation Model Minutia
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Outline Project Background Model Scope –Geography –Time Periods & Vehicle Population Model Preparation Model Minutia
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Lake County
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Lake County 450 square miles of Lake County, from Middletown (Napa border) to Upper Lake (Mendocino border)
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Lake County
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Lake County 720 miles of roadway (120 miles on State Routes) 4,200 Links and 3,300 Nodes All roads in the regional travel demand model are included
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Lake County High level of detail for local streets Nice
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Lake County Intersection geometry accurately reproduced
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Outline Project Background Model Scope –Geography –Time Periods & Vehicle Population Model Preparation Model Minutia
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Time Periods & Vehicle Population Times of day include two peak periods –6:00 – 9:00 AM –3:00 – 6:00 PM Vehicle Population –Auto –Truck
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Time Periods & Vehicle Population Times of day include two peak periods –6:00 – 9:00 AM –3:00 – 6:00 PM Vehicle Population –Auto –Truck
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Outline Project Background Model Scope Model Preparation –Data Collection –Model Calibration –Model Validation Model Minutia
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Outline Project Background Model Scope Model Preparation –Data Collection –Model Calibration –Model Validation Model Minutia
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Data Collection GPS-recorded travel times O-D surveys Turning movement counts Directional counts
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Data Collection O-D Survey Sites (5) Turning Movement (20) Directional Counts (26) GPS Travel Times
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Data Collection Turning Movement (20) Directional Counts (26) GPS Travel Times O-D Survey Sites (5)
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Data Collection O-D Survey Sites (5) Directional Counts (26) GPS Travel Times Turning Movement (20)
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Directional Counts (26) Data Collection O-D Survey Sites (5) Turning Movement (20) GPS Travel Times
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Outline Project Background Model Scope Model Preparation –Data Collection –Model Calibration –Model Validation Model Minutia
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Model Calibration Take the calibrated travel demand model as the starting point Iteratively cycle between –Trying to match turn & directional counts –Trying to equilibrate route choices Target traffic count calibration standards set by Caltrans
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Model Calibration Take the calibrated travel demand model as the starting point Iteratively cycle between –Trying to match turn & directional counts –Trying to equilibrate route choices Target traffic count calibration standards set by Caltrans Calibrated Travel Demand Model Match Counts (ODME) Match Times (DTA) Calibrated Micro-simulation Model
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Model Calibration Take the calibrated travel demand model as the starting point Iteratively cycle between –Trying to match turn & directional counts –Trying to equilibrate route choices Target traffic count calibration standards set by Caltrans
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Outline Project Background Model Scope Model Preparation –Data Collection –Model Calibration –Model Validation Model Minutia
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Model Validation Take the calibrated traffic simulation model as the starting point Iteratively cycle between –Trying to match point-to-point travel times –Reviewing/revisiting model development and calibration steps Target travel time calibration standards set by Caltrans
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Model Validation Take the calibrated traffic simulation model as the starting point Iteratively cycle between –Trying to match point-to-point travel times –Reviewing/revisiting model development and calibration steps Target travel time calibration standards set by Caltrans Calibrated Traffic Simulation Model Revisit Calibration (ODME/DTA) Match Times (Simulation) Validated Micro-simulation Model
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Model Validation Boundary Upper Lake Lucerne SR-53 Lower Lake Kelseyville Middletown Point-to-Point Travel Times
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Boundary Upper Lake Lucerne SR-53 Lower Lake Kelseyville Middletown Model Validation AM Southbound Travel Times
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Boundary Upper Lake Lucerne SR-53 Lower Lake Kelseyville Middletown Model Validation AM Northbound Travel Times
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Boundary Upper Lake Lucerne SR-53 Lower Lake Kelseyville Middletown Model Validation PM Southbound Travel Times
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Boundary Upper Lake Lucerne SR-53 Lower Lake Kelseyville Middletown Model Validation PM Northbound Travel Times
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Model Validation
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Lower and Upper Bounds calculated by bootstrapping sample
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Model Validation Lower and Upper Bounds calculated by bootstrapping sample 1.Create bootstrapped sample of the set of simulation runs 2.For each run in bootstrapped sample, create bootstrapped sample of point-to-point travel times 3.Calculate expected travel time for each simulation run
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Model Validation Lower and Upper Bounds calculated by bootstrapping sample 1.Create bootstrapped sample of the set of simulation runs 2.For each run in bootstrapped sample, create bootstrapped sample of point-to-point travel times 3.Calculate expected travel time for each simulation run Which is to say this is NOT an average of all of the point-to- point travel times
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Model Validation
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Outline Project Background Model Scope Model Preparation Model Minutia –Curvature –Grade –Lane Width –Two-lane Highway Passing
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Outline Project Background Model Scope Model Preparation Model Minutia –Curvature –Grade –Lane Width –Two-lane Highway Passing
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Curvature
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Radius of 20ft, curvature of (1/20ft)*1000ft = 50 in Segment layer
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Curvature
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Maximum speed is constrained by the radius
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Curvature
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Curvature at which maximum speed 55 mph
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Curvature Reduction in Travel Time for two pairs with most curvature
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Outline Project Background Model Scope Model Preparation Model Minutia –Curvature –Grade –Lane Width –Two-lane Highway Passing
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Grade
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30 ft of elevation gain, from USGS DEM Grade 1,000 ft long
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Grade 3% Grade
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Grade 3% Grade Effect on Acceleration Effect on Max. Speed
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Grade
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Now looking at statistics across all point-to-point Travel Times (not at simulation run level)
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Grade Effect is opposite for uphill vs. downhill
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Outline Project Background Model Scope Model Preparation Model Minutia –Curvature –Grade –Lane Width –Two-lane Highway Passing
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Lane Width
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12 ft lane 11 ft lane 10 ft lane
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Lane Width 12 ft lane 11 ft lane 10 ft lane
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Lane Width
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Back to Expected Travel Time
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Lane Width Travel Time drops without Lane Width restriction
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Outline Project Background Model Scope Model Preparation Model Minutia –Curvature –Grade –Lane Width –Two-lane Highway Passing
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Two-lane Highway Passing
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Two-Lane Highway Passing
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Now looking at statistics across all point-to-point Travel Times (not at simulation run level)
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Two-Lane Highway Passing Generally increases travel time, as expected Exceptions are due to network effects
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Conclusion Lane level detail is essential for accurate modeling of rural and exurban regions
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Conclusion Lane level detail is essential for accurate modeling of rural and exurban regions, and, as a corollary, microsimulation is essential for accurate modeling of rural and exurban regions
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Thank you david@caliper.com
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