MEPDGImplementation:

Arkansas

13 January 2008Washington, DC

Kevin D. Hall, Ph.D., P.E.Kevin D. Hall, Ph.D., P.E.Professor and HeadProfessor and HeadDept. of Civil EngineeringDept. of Civil EngineeringUniversity of ArkansasUniversity of Arkansas

Where do you attack the Beast?

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ClimateTraffic

Materials

Structure

DistressResponseTime

Damage

Damage Accumulation

Arkansas’ MEPDG Activities

• “First Look”– Sensitivity Analyses

• Materials Characterization– Hot‐mix asphalt– Portland cement concrete– Unbound materials

• Traffic Characterization• Design Studies• Local Calibration Research

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Sensitivity Analyses

• Identify those inputs most critical in distress predictions– Provided a ‘head start’ to material characterization studies

• Numerous studies completed around the U.S. to date

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Materials: Hot‐Mix Asphalt

• Dynamic Modulus (E*) – 3 NMAS

– 3 Binder Grades

– 4 Agg Types

– 2 Gradations

• Created catalog of E* data for “Level 1” design

• Assessed suitability of Level 3 predictive equation

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Materials: PCC

• Coefficient of ThermalExpansion (CTE)

• Poisson’s Ratio• Modulus of Elasticity

– 5 Agg types– Time Series Values

• Effect of Paste• Catalog of Values• Assessment of Predictive

Relationships

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Traffic Studies

• The Good…– 7 TTCs identified statewide

– Default monthly & hourly distribution factors suitable for use

– Developed statewide vehicle class distribution factors

– Developed statewide Axle Load Spectra

• The Bad…– TRAFLOAD could not be used; spreadsheets developed

• The Ugly…– Only 25 of 55 WIM sites suitable/comprehensive for traffic study

• Classification data: 17 of 25 sites passed quality checks• Weight data: 10 of 25 sites passed quality checks

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Design Studies

• Comparing designs with ‘current practice’– Aid in identifying initial performance criteria

• Developing comprehensive database structure to integrate design, construction, performance / PMS data

• Developing “Design Handbook”

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Example: “Design Handbook”

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General Traffic Inputs

Mean wheel locationUse default value shown

Traffic wander std. deviationUse default value shown

Design lane widthEnter lane width in feet

Average axle widthUse default value shown

Dual tire spacingUse default value shown

Tire pressure(s)Use default value(s) shown

Axle spacing(s)Use default value(s) shown

Local Calibration Efforts

• Potential ‘existing’ section identification– LTPP sites within Arkansas– ‘top 25’ Superpave sites

• Primarily modified binders

• Guidelines for data collection: new construction– Design– Construction– Performance Monitoring

• Database Construction

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Database Structures

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Climate Module: Database Structure

• MEPDG_Climate_Stations• MEPDG_Climate_Hourly• MEPDG_Climate_Daily• MEPDG_Climate_Seasonal

• MEPDG_Climate_GWT_General• MEPDG_Climate_GWT_Depth

• MEPDG_Climate_Elevation

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Climate Module: Software Features

• Generate A Virtual Weather Station – GPS Coordinates of Project Under Design– Closest 6 Weather Stations & WTD Points– Interpolation: Inversely Weighted by Distances– Prepare “*.icm” File for Specific Design

• Summary Report: Show the Location of the Prepared Climate File

• Produce A Geo-Referenced Map to Show the Geographical Relationships

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Climate Module: Geo‐Mapping Utility

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Climate Module:  User Software

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Traffic Module: MEPDG Software

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Traffic Module: Traffic Monitoring In Arkansas

WIM SitesVehicle Classification SitesVolume Count Only SitesNon-Operational Sites

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Traffic Module: Database Structure

• MEPDG_Traffic_Stations_Yearly• MEPDG_Traffic_Volume_Daily• MEPDG_Traffic_Vehicle_Class_Monthly• MEPDG_Traffic_Weight_Single_Monthly• MEPDG_Traffic_Weight_Tandem_Monthly• MEPDG_Traffic_Weight_Tridem_Monthly• MEPDG_Traffic_Weight_Quad_Monthly

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Traffic Module: QC Data Check (Vehicle Classification)

• Completeness of the Data– Error in Dates, Months, State Code, etc– Exactly 24 Hours A Day– Days W/O A Single Vehicle

• QC Procedure (FHWA, LTPP, TRC 0402)– Compare Manual Counts with WIM Data– Check the # of Class 1 (Motorcycles)– Check the # of Unclassified Vehicles – Data W/O Significant Change

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Traffic Module: QC Data Check (Vehicle Weight)

• Based on Class 9 Vehicles (Main Truck Type)• QC Procedure

– Check the Weight of Front Axle– Check the Weight of Drive Tandem Axle– Check the Gross Vehicle Weights – # of Vehicles Over the Legal Weight Limit

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Traffic Module: Data Quality Control

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Traffic Module: Software Features

• Generate Required 11 Traffic Files– Based on TTC Class

• Six TTC Classes from TRC 0402• If No Idea: Statewide Average• HFC: Preliminary Implementation Stage

• Summary Report to Show the Location of the Prepared Traffic Files

• A Geo-Referenced Map to Show the Geographical Relationships

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Materials Module: Inputs

• General Inputs – 4 Tables• Asphalt Concrete (AC) – 7 Tables• Portland Cement Concrete (PCC) – 5 Tables• Stabilized Base – 1 Table• Unbound Materials / Subgrade – 2 Tables• Bedrock – 1 Table

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Materials Module: Retrieval Software

• Dynamic Modulus• CTE• MR

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Project Files: Pavement Performance

• Ride (IRI)• Distress

- AC: cracking, rutting- JPCP: cracking, faulting- CRCP: punchouts

• Structure/Stiffness (FWD, GPR)• Friction

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Project Files: Construction

• Construction (11)• Field Materials Sampling (4)• AC Construction Related Testing (12)• PCC Construction Related Testing (6)• Stabilized Materials Construction Related

Testing (2)• Unbound Materials and Subgrade

Construction Related Testing (7)

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Project Files: Maintenance

• Seal Coats• Crack Sealing• Patching• Joint Sealing• Grinding• Milling• Grooving

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Database Tables

Arkansas’ MEPDG Investment

• “First Look”– Sensitivity Analyses complete $176k

• Materials Characterization– Hot‐mix asphalt complete $330k

– Portland cement concrete ongoing $250k

– Unbound materials (“complete”) ????

• Traffic Characterization complete $  81k

• Design Studies ongoing$375k

• Local Calibration Research  (3 studies)Total Research Commitment (to date): $1.2M+29

Arkansas’ Bottom Line…

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