WHAT IS AASHTOWare PAVEMENT ME - virginiadot.org · Current practice is 1993 AASHTO pavement design...
Transcript of WHAT IS AASHTOWare PAVEMENT ME - virginiadot.org · Current practice is 1993 AASHTO pavement design...
WHAT IS AASHTOWare PAVEMENT ME –
VDOT’s New Pavement Design Software?
Affan Habib, PE
Pavement Program Manager
VDOT Materials Division
October 3, 2017 - Richmond, VA
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Outline
I. Introduction and background of
MEPDG
II. Overview of MEPDG design
process
III. VDOT MEPDG Implementation
Overview
IV. Impact of MEPDG Implementation
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I. INTRODUCTION AND BACKGROUND OF MEPDG
PROCEDURE
What is AASHTOWare
PavementME?
• VODT’s New Pavement Design Software
• From 1/1/2018
• Developed by AASHTO
• Software for a totally different method of pavement
design: MEPDG
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VDOT’s MEDG Implementation
Plan At a Glance
▪ Where does VDOT plan to use MEPDG?
• Interstate and Primary routes.
▪ New alignment, reconstruction, and lane widening
▪ Rehab design: sometime in the future
• Continue to use VDOT’s Secondary & Subdivision
Pavement Design Guide & Procedures on Secondary
& Subdivision streets
▪ Some high volume secondary roads with AADT >
10,000 maybe designed using MEPDG at discretion of
Districts Material Engineer.
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What is Mechanistic Empirical Pavement
Design Guide (MEPDG)?
▪ Design based on measurable performance (e.g.,
rutting, cracking etc.)
▪ Based on Mechanistic-Empirical principles
Mechanistically:It calculates pavement responses(stresses, strains, and
deflections) due to loading and environment and uses those
responses to compute incremental damage overtime.
Empirically:
It relates the cumulative damage to observed pavement
distresses (i.e. IRI, rutting, cracking, faulting, and punchout etc.)6
Why Do We Need a New Pavement
Design Procedures/Software?
▪ Current practice is 1993 AASHTO pavement design guide• Developed between late 50s and late 90s
• Based on AASHO Road test
▪ VDOT adopts 1993 process in early 2000
▪ AASHTO declared sun set on 1993 design software (e.g., Darwin)
▪ 1993 design has lot of limitations (one location, one subgrade, < 2 Million ESALs, and 1950s construction)
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MEPDG Development
• 1993 pavement design method paved the way for MEPDG
▪ Developed based on the LTPP performance data
▪ Across USA and Canada
▪ Various NCHRP studies
▪ Balloted and accepted in 2007
▪ Enhancements ongoing
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▪ Implemented (Asphalt pavement and/or overlays):
14 states
▪ Planning to implement (Asphalt pavement and/or
overlays): 31 states
9Source: MEPDG National User Group
Meeting , December 2016
How many states are adopting
MEPDG?
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II. OVERVIEW OF MEPDG DESIGN PROCESS
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MEPDG Design Process
Climate
Traffic
Layer Properties
Stress,
Strain, or
DeflectionTRANSFER
FUNCTION
Materials
Distress
Performance Threshold
Adjustment
▪ Minimizes the limitations of the 1993 process
▪ Improved handling of climatic effects and traffic
loadings
▪ Various hierarchical Input Levels
▪ Depending on availability and importance
▪ Relating between design and performance
▪ Ability to calibrate and set threshold limits to local
conditions
▪ It is not all about thickness
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Benefits of MEPDG Design
MEPDG: It’s Not All About
Thickness (all the time)
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6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
22.00
24.00
0.00 10.00 20.00 30.00 40.00 50.00 60.00
AC
Th
ickn
ess, In
ch
ESAL, Millions
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▪ Ability to analytically assess impact of specification
changes (ex. Binder content, air void, and gradation).
Other Potential Benefits of
MEPDG
0.1
0.15
0.2
0.25
0.3
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
3.0 4.0 5.0 6.0 7.0 8.0 9.0
Ru
ttin
g in
inch
es
Bo
tto
m-u
p C
rack
ing
(%)
Binder Content by weight (%)
Effect of Binder Content on Bottom-up Cracking and Rutting
Bottom-up Cracking
Rutting
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Other Potential Benefits of
MEPDG
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3
4
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4 5 6 7 8 9 10 11 12
Bo
tto
m-u
p C
rack
ing
(%)
Air Void (%)
Effect of Increased Density on Performance
Bottom-up Cracking
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Other Potential Benefits of
MEPDG
Study Average Reduction in Fatigue Life for 1% Air
Void Increase
UC Berkeley (1969) 27.20%
UCB (1996 15.10%
WesTrack (2002) 11.90%
Al (2010) 9.20%
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2
3
4
5
6
7
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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Bo
tto
m-u
p C
rack
ing
(%)
Year
Effect of Air Voids to Bottom-Up Cracking
7% Air Void
8% Air Void
III. VDOT MEPDG
IMPLEMENTATION OVERVIEW
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▪ VDOT planned MEPDG implementation in mid 2000
▪ VDOT was one of the 15 lead agencies to implement
MEPDG
▪ Significant works were deemed needed
• Materials, traffic, local calibration, training etc.
▪ Started ‘shadow’ design from 2014
▪ Official implementation date set at January 1, 2018
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VDOT’s MEPDG Implementation
at a Glance
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Develop Inputs
Materials
Traffic
Climate
Training
Staff
Software
Review Models
Local Calibration
Understanding output
Policy
Connect with VDOT business practices
Current status
VDOT’s MEPDG
Implementation Plan/Status
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▪ Objective: “No Surprise”
▪ Technical Working Group (TWG)
• Members (VDOT, VTRC, Industry, FHWA)
• Work on technical issues
(user manual, modelling, and input values)
• Meets once a month to discuss on technical issues
▪ Stakeholder Group
• Consists of VDOT, FHWA, VTRC and Industry
• Periodic updates on progress & timeline
MEPDG Implementation: Extensive
Outreach
▪ VDOT has developed MEPDG User Manual. Available
in VDOT external site for downloading: http://www.virginiadot.org/business/materials-download- docs.asp
▪ VDOT will change the User Manual periodically
▪ Updates on MOI Chapter III and VI were included in
regards to MEPDG
▪ All VDOT specific inputs files are available in VDOT
external site for downloading:http://www.virginiadot.org/business/materials-download-docs.asp
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How Does All These Incorporated
into Practice?
IV. IMPACT OF MEPDG
IMPLEMENTATION
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▪ Different input parameters
▪ Good News - Input parameters were developed and available
for VDOT and external users.
▪ Traffic
▪ No change in data collection
▪ ADT, truck %, growth rate etc.
▪ Subgrade investigation & testing
▪ Some changes in the investigation/reporting
• AASHTO soil classification
• Estimation of Resilient Modulus (RM) from unconfined
compressive strength test
• No CBR – Resilient Modulus correlation to determine (RM)
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What Will MEPDG Change for
Contractors, Consultant & DBer?
▪ Materials input
• Designer does not need to gather additional data (AC, PCC, and
aggregate).
(http://www.virginiadot.org/business/materials-download- docs.asp)
▪ Environmental Input
• Designer does not need to gather additional data.
(http://www.virginiadot.org/business/materials-download- docs.asp)
▪ Personnel Training
▪ Different Software - AASHTOWare Pavement ME version
2.2.6
• $ 5,500 per license/year
• Can be procured through AASHTO
http://www.aashtoware.org/Pavement/Pages/default.aspx24
What Will MEPDG Change for
Contractors, Consultant & DBer?
VDOT’s MEPDG Implementation
Plan At a Glance
▪ Where does VDOT plan to use MEPDG?
• Interstate and Primary routes.
▪ New alignment, reconstruction, and lane widening
▪ Rehab design: sometime in the future
• Continue to use VDOT’s Secondary & Subdivision
Pavement Design Guide & Procedures on Secondary
& Subdivision streets
▪ Some high volume secondary roads with AADT >
10,000 maybe designed using MEPDG at discretion of
Districts Material Engineer.
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