george white, ceo pavia systems

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A simplified pavement design tool using AASHTO 93/98

George White, CEOPavia Systems

PaveXpress

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From dilbert.com

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TRANSPORTATION INFRASTRUCTURE IS FUNDAMENTAL TO OUR WAY OF LIFE. Why we do what we do…

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To transform the capabilities of organizations in the transportation industry through the practical use of remarkable technologies.

PAVIA’S MISSION

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Version 2.0 - A Simplified Pavement Design Tool

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Why PaveXpress?

AASHTO has been developing MEPDG for high volume roads, but a gap has developed for local roads and lower volume roads.

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Application Objectives

Provide tool to develop technically sound new and rehabilitation pavement designs for roadway and parking lot pavements

Provide a user-friendly, visually appealing, pavement design tool accessible to users on a variety of devices

Provide a free application for conducting pavement designs following 1993 and 1998 AASHTO

Provide resources to enhance understanding and comfort with pavement design

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Application Users

• Local Government Agencies

• A/E/C Firms• Engineering Students• State Transportation

Agencies• FHWA• Foreign Companies and

Governments

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Guiding Principles for Application

• Provide accurate un-biased results…be a trusted resource

• Only ask the user for what is required to perform a technically sound design

• Where appropriate suggest industry accepted defaults to minimize user input

• Provide context sensitive help and guidance

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I don’t always do pavement designs, but when I do, I prefer PaveXpress.

Image from themostinterestingblogintheworld.com

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Approach: Technical• Provide technically sound

designs using:– Flexible: AASHTO ’93– Rigid: AASHTO ‘93 w/ ‘98

Supplement– Parking lot guidance

(Flexible only)• Use industry accepted

standards and guidance• Linkages to State and

Local guidance• Linkages to Pavement

Interactive

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The equation was derived from empirical information obtained at the AASHO Road Test.

The solution represents the average amount of traffic that can be sustained by a roadway before deteriorating to some terminal level of serviceability, according to the supplied inputs.

1993 AASHTO Design Guide Equation — Basic Overview

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Where:W18 = the predicted number of 18-kip equivalent single axle load (ESAL) applicationsZR = standard normal deviateS0 = combined standard error of the traffic prediction and performance predictionΔPSI = difference between the initial design serviceability index (pi) and the design terminal

serviceability index (pt)MR = resilient modulus of the subgrade (psi)

log10 𝑊𝑊18 = 𝑍𝑍𝑅𝑅 × 𝑆𝑆0 +9.36 × log10 𝑆𝑆𝑆𝑆 + 1 − 0.20 +log10

∆𝑃𝑃𝑆𝑆𝑃𝑃4.2 − 1.5

0.4 + 1094𝑆𝑆𝑆𝑆 + 1 5.19

+ 2.32 × log10 𝑀𝑀𝑅𝑅 − 8.07


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www.PaveXpressDesign.com 15

Where:W18 = the predicted number of 18-kip equivalent single axle load (ESAL) applicationsZR = standard normal deviateS0 = combined standard error of the traffic prediction and performance predictionD = slab depth (inches)ΔPSI = difference between the initial design serviceability index (pi) and the design terminal serviceability index (pt)S′c = modulus of rupture of PCC (flexural strength)Cd = drainage coefficientJ = load transfer coefficientEc = elastic modulus of PCCk = modulus of subgrade reaction


log10 𝑊𝑊18 = 𝑍𝑍𝑅𝑅 × 𝑆𝑆0 + 7.35 × log10 𝐷𝐷 + 1 − 0.06 +log10

∆𝑃𝑃𝑆𝑆𝑃𝑃4.5 − 1.5

1 + 1.624 × 107𝐷𝐷 + 1 8.46

+ 4.22 − 0.32𝑝𝑝𝑡𝑡 × log10𝑆𝑆𝑐𝑐′ 𝐶𝐶𝑑𝑑 𝐷𝐷0.75 − 1.132

215.63 𝐽𝐽 𝐷𝐷0.75 − 18.42

�𝐸𝐸𝑐𝑐 𝑘𝑘0.25

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The designer inputs data for all of the variables except for the structural number (SN), which is indicative of the total pavement thickness required.

Once the total pavement SN is calculated, the thickness of each layer within the pavement structure is calculated

Where:ai = ith layer coefficientDi = ith layer thickness (inches)mi = ith layer drainage coefficient

𝑆𝑆𝑆𝑆 = 𝑎𝑎1𝐷𝐷1 + 𝑎𝑎2𝐷𝐷2𝑚𝑚2 + 𝑎𝑎3𝐷𝐷3𝑚𝑚3 + ⋯+ 𝑎𝑎𝑖𝑖𝐷𝐷𝑖𝑖𝑚𝑚𝑖𝑖

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New to Version 2.0• AC Overlay Design for Flexible

Pavement Rehabilitation Only• Evaluation Methods for

Existing AC Pavement– Condition Survey– Non-Destructive Deflection

Testing• Includes Questions on Coring

and Milling– Delamination/Stripping– Top-Down or Bottom-Up

Cracking• Adjustment to Existing

Pavement Layer Coefficients

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Before Getting Started

Need to have:Knowledge of existing

pavement structureKnowledge of subgrade

conditionKnowledge of surface

conditionTraffic level for design

period

Nice to have:Cores of roadway

(cracks in particular)Subgrade modulus testsNDT data Policy on reliability and

serviceability level

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LET’S TAKE A CLOSER LOOK!A sneak preview at some of the highlights.

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Home page: Welcome to PaveXpress

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Navigation up top, resources to familiarize you

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Background Information is available

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Linked and integrated to Pavement Interactive

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Frequently asked questions

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You must register with email and password.

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Once logged in, go to My Projects to view your designs

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Create and manage your folders of designs

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Create a new project and design at the click of a button

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Give it a name and location

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A clean, step wise process for creating the design

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1. Start with general project information, locations

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2. Expand into design parameters

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Context sensitive help linked to resources throughout

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Enter traffic and loading information

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Calculate traffic from AADT using AASHTO methods

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Completion year traffic is set, now on to LEF

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Create composite load equivalency factor

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Specify your surface layer information

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Warnings where appropriate to alert of changes

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Enter your base layer and subgrade information

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Add multiple base layers if needed

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And enter your subgrade…can use conversion tables

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And voila…a design and resources are available

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And the calculations are shown

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Iterate back and forth to check sensitivity, add layers

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For Rigid, a similar process with a few alterations

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Additional design parameters for weather

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Specify the surface characteristics

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Specify the base characteristics

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And again, voila, a design is presented with calculations

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Parking lots you ask?

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Light duty points directly to local guidance (catalogs)

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Takes you to local guidance from OAPA

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Some other capabilities you should be aware of

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Organize, store, and print your designs

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Share your design directly from PaveXpress via email

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Compare up to 3 designs side by side

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LETS RUN THROUGH SOME DESIGN SCENARIOS LIVE

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Future of PaveXpress

A framework to continue to build upon:• Simplified mechanistic design for Asphalt

Pavements– Linear Elastic Analysis (EverStress)

• Cost estimating module

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QUESTIONS?

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A Simplified Pavement Design Tool

www.PaveXpressDesign.com

george white, ceo pavia systems

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