Road Pavements Forum Structural Design Working Group

Revision of the South African Flexible Pavement Design Method

7 November 2006

Pretoria

H L Theyse

Slide 2 © CSIR 2006 www.csir.co.za

Research and Development (R&D) Framework

• Pavement Design Task Group• Established May 2005• Series of meetings during July and August 2005• R&D framework submitted in November 2005

• Characteristics of new pavement design method• R&D topics

• Performance based information system• Demand analysis (Traffic and environment)• Material resilient response models • Pavement resilient response models• Damage models • Probabilistic and recursive schemes

• Each R&D topic have a number of identified R&D needs• Each R&D need is currently being translated into one or more project

briefs to address those needs

Slide 3 © CSIR 2006 www.csir.co.za

R&D Process

• Project funding and contracts• Funding organisations will sponsor projects of interest to them• Contract between service provider and project client

• Project management• Each project will start with an inception phase

• Investigate available solutions• Finalize project methodology• Finalize cost and resource allocation

• Ongoing project review through existing structure of Road Pavements Research Advisory Committee (RPRAC) to ensure correct delivery on time

Slide 4 © CSIR 2006 www.csir.co.za

R&D Process (continued)

• Overarching integration level project• Integration of output from various ME-design related projects• Integration of performance based information system with ME-design

components in a single design method

• Delivery mechanisms• Website for tracking progress on R&D process and sharing general

information• Any content (documents and software) developed as part of the

project available for use on the project website• Immediate, short, medium and long-term output

• User-manual with an overview of the method• Detail technical documents on individual components• Technical guidelines, test protocols and method specifications

Slide 5 © CSIR 2006 www.csir.co.za

Project objectives

• Overall objective• To develop a design method that is

• Accurate (agree with reality)• Impartial in terms of pavement type selection

• Unbound (Crushed stone, natural gravel)• Stabilised (Cement, Foamed-bitumen, Emulsified-bitumen)• HMA• Concrete (not included in flexible pavement design R&D process)

• Project structured according to immediate, short, medium and long-term objectives and deliverables• Achievement of objectives subject to availability of resources

Slide 6 © CSIR 2006 www.csir.co.za

Time-frame for R&D process

Immediate 12 to 18 months

Short-term 3 to 5 years

Medium-term 5 to 8 years

Long-term 8 to 12 years

Slide 7 © CSIR 2006 www.csir.co.za

Revised design method

• Integration of two components• Information system based on past performance • Mechanistic-Empirical analysis and design system

• Performance based information system• Starting point for design – coupled with ME-design using default

input values for preliminary design and training• Validation data set for reality checks and calibration

• ME-design component• Provides opportunity for design refinement

• Project specific input combined with design expertise• Utilisation of available road-building material

Slide 8 © CSIR 2006 www.csir.co.za

Integration of past performance and M-E design components

Design Method

Young professional

Seasoned professional

Design specialist

Design scenario:• Routine and preliminary design• Low risk• Low design experience• Known materials – default input• Conventional material classification

Design scenario:• Important design• Medium risk • Seasoned professional designer• Project specific input

Design scenario:• Very important design, high risk• Special investigations • Specialist designer• Unusual materials• Project specific input

User Design application

Performance based

information system

ME-design component

Slide 9 © CSIR 2006 www.csir.co.za

Work in progress

• Performance based information system• Modelling and Analysis Systems CC appointed to develop and

populate the system

• ME-design component• CSIR Built Environment appointed for inception phase

• Develop project briefs – 22 briefs• Industry workshop – 15 November 2006• Project website linked to RPRAC website

Slide 10 © CSIR 2006 www.csir.co.za

Temperature

Moisturecontent

Density

Grading

Atterberglimits

Bindercontent

Binderproperties

Geometry

PB/2006/A-2

Other?

Other?

PB/2006/A-1

Grading

PB

/2006/B-1b

PB

/2006/B-1a

PB

/2006/B-1c

UCS

Stress and strain at break

Time/previousloading

HM

AU

nbou

ndS

tabi

lized

PB

/200

6/B

-4

PB/2006/A-3PB/2006/A-4

PB/2006/C-1

PB/2006/C-3

PB/2006/C-4

PB/2006/C-5

Resilientresponse models

Damage models

PB/2006/D-1

HM

AU

nbou

nd

PB/2006/D-2

Other?

Sta

biliz

ed

PB/2006/D-3

Sub

grad

e

PB/2006/D-2

PB/2006/E-3

Com

pute

rso

lutio

n

PB/2006/E-1 and PB/2006/E-2

PB

/2006/B-2 an

d P

B/2006/B

-3PB/2006/C-2

PB

/200

6/B

-4

Slide 11 © CSIR 2006 www.csir.co.za

Slide 12 © CSIR 2006 www.csir.co.za

Structural Design Working Group Progress

• Performance based information system due for completion in August 2007

• ME-design component• Preparation nearly completed

• R&D framework• Project briefs to be finalised after 15 November

• Project work to start in 2007

Slide 13 © CSIR 2006 www.csir.co.za

Announcement …..

• In the light of the CSIR mandate, CSIR Built Environment has decided to distribute Pavement Analysis and Design Software (PADS) free of charge from mid-2007• Me – PADSTM

• Back - PADSTM

• Traf - PADSTM

• Pro – PADSTM

• User certification required - training course• Launch at May 2007 RPF