pavement design good ref

Document Number: AD-D-09First Edition - May 2013

PAVEMENT DESIGN MANUAL

Commentary Report

PAVEMENT DESIGN MANUAL COMMENTARY REPORT

BY PARSONS INTERNATIONAL LIMITED

DOCUMENT NO: AD-D-09 FIRST EDITION

MAY 2013

Document No: AD-D-09 First Edition

May 2013 Department of Transport

PO Box 20 Abu Dhabi, United Arab Emirates

Copyright 2013, by the Department of Transport. All Rights Reserved. This manual, or parts thereof, may not be reproduced in any form without written permission of the publisher.

Page i

Contents Approval and Amendment Record

This report has been issued and amended as follows:

Issue

Revision

Description

Lead Author

Lead Reviewer

Date

1.0

0

Report to accompany draft final of Pavement Design Manual submitted to Review Committee

Mohamed Elbasyouny

(PIL)

Mohamed Elbasyouny

(PIL)

6/05/2013

Page ii

TABLE OF CONTENTS List of Figures .............................................................................................................................. iii List of Tables ................................................................................................................................ iii Executive Summary ...................................................................................................................... 1 1 Introduction ............................................................................................................................ 2 2 methodology .......................................................................................................................... 3 3 background and history ........................................................................................................ 4 4 base documents .................................................................................................................... 5

4.1 1993 AASHTO Empirical method ...................................................................................... 5 4.2 Austroads Mechanistic-empirical method .......................................................................... 5 4.3 Abu Dhabi Municipality Pavement Design Manual ............................................................ 7

5 scope of manual .................................................................................................................... 8 5.1 Application of this manual ................................................................................................. 8 5.2 Content and format ........................................................................................................... 8

6 Document development ...................................................................................................... 10 6.1 Progress meetings .......................................................................................................... 10 6.2 Consultation meetings .................................................................................................... 10 6.3 Formal submission .......................................................................................................... 10 6.4 Workshop ....................................................................................................................... 11 6.5 Comment Review ........................................................................................................... 11 6.6 Final submission ............................................................................................................. 11

7 Acknowlegment ................................................................................................................... 13 Appendix A: compiled comments from Dot/ stakeholders ...................................................... 15 Appendix B: workshop presentation ......................................................................................... 26

Page iii

LIST OF FIGURES Figure 1 Mechanistic-Empirical Design Method Flowchart .............................................................. 7

LIST OF TABLES Table 1 Technical Meetings Information ........................................................................................ 12

EXECUTIVE SUMMARY In 2010, the Department of Transport commenced with the Unifying and Standardizing of Road Engineering Practices Project. The objective of the project was to enhance the management, planning, design, construction, maintenance and operation of all roads and related infrastructures in the Abu Dhabi Emirate and ensure a safe and uniform operational and structural capacity throughout the road network.

To achieve this objective a set of 36 standards, specifications, guidelines and manuals were developed in consultation with all relevant authorities in the Abu Dhabi Emirate. In future, all authorities or clients involved in roads and road infrastructures in the Emirate shall exercise their functions and responsibilities in accordance with these documents.

One of these 36 manuals is the Pavement Design Manual (PDM). The PDM focuses on the material characterization, traffic estimation and climatic influence for the structural design of the pavements structural layers. Combining conditions and resources from different international manuals, while including ways to use sustainable and economical materials, this manual is highly applicable to Abu Dhabi.

This manual provides comprehensive information needed to develop complete structural pavement designs for both flexible (asphalt) and rigid (concrete) pavements. Topics covered in PDM include required traffic and climatic data for pavement design, material characterization, new pavement design, rehabilitation techniques, pavement maintenance, pavement management, low volume roads, evaluation of existing pavements condition and life cycle cost (LCC) analysis. This manual also covers the empirical and the mechanistic-empirical (M-E) design methods. Using the information in this manual, a designer can apply several design methods and select a final design based on a life cycle cost analysis.

In coordination with DoT and Aurecon (Project Manager), following process was identified and followed:

Get comprehensive brief from DoT Staff to understand their requirements. Submit Preliminary report to confirm DoTs requirements. Review the existing International pavement design manuals. Conduct an initial workshop to discuss the draft contents and methodology to be adopted. Prepare and submit a first draft Manual for comments and review by DoT. Receive comments from DoT and improve the draft. Submit a second draft for DoT / Stakeholders review. All agencies to attend a workshop to receive comment and thereby improve the draft. Collect comments from the workshop outcome and prepare a final manual.

All the Chapters and Appendices of the PDM were developed in complete co-ordination with DoT. Several chapters were submitted individually for DoT review during the development process. However, the first complete draft of the PDM was delivered for review in April 2012. The document has been subject to further rigorous review during several meetings with DoT lead reviewer. The second full draft of the document was delivered for review in September 2012. In November 2012 a workshop was held for all agencies to present the draft final and collect their comments. In mid December 2012 after meeting with DoT and other manuals developer a new chapter was requested to be added. Finally, in February 2013 the final draft manual was submitted.

1 INTRODUCTION Pavement design, an integral and critical part of the transportation system, focuses on thickness design of pavement layers. In general, pavement design requires knowledge about the materials in any existing pavement layers, the foundation upon which the pavement will reside, traffic levels, and climatic conditions. Selecting a final design, however, depends on the availability of materials, funding, and local experience.

The manuals approach is consistent with DoTs objective to upgrade the existing pavement design methodology by incorporating advanced technology and pavement design procedures. This manual provides comprehensive information needed to develop complete structural pavement designs for asphalt and concrete pavements. Topics include required data, material characterization, new pavement design, rehabilitation techniques, pavement maintenance, pavement management, low volume roads, and life cycle cost (LCC) analysis. This manual also covers the empirical and the mechanistic-empirical (M-E) design methods. Several pavement design methods are currently used by different agencies and countries. These methods vary somewhat for differing local conditions and resources. The procedures range from empirical to M-E approaches. New M-E pavement design analysis procedures developed over the last 20 years focus on the design and construction of high quality, long-lasting and well-performing highways that accommodate the increase in traffic volumes and loads in ways that exceed the empirical methods. These new approaches are challenging in that they require advanced analysis methods and material characterization. In response to these technical advances and increasingly easy computation, DoT has incorporated the newer and more fundamental mechanistic-empirical design approaches in this new manual.

Combining conditions and resources from different international manuals, while including ways to use sustainable and economical materials, this manual is highly applicable to Abu Dhabi. It covers different options for obtaining traffic count and loads, environmental factors, and advanced material characterizations that apply to Abu Dhabi. Brief descriptions for some pavement design topics are given since other DoT manuals cover such topics in more details.

This report supports the PDM manual, as it summarizes the approach followed in developing the PDM. The report also, provides the activities undertaken and communications with DoT to develop the PDM in its final version.

2 METHODOLOGY The method followed to develop the pavement design manual was set from the start of the project with the DoT and Aurecon (Project Manager). The following process was identified and followed:

1. Get comprehensive brief from DoT Staff to understand their requirements. 2. Submit Preliminary report to confirm DoTs requirements. 3. Review the existing International pavement design manuals. 4. Conduct an initial workshop to discuss the draft contents and methodology to be adopted. 5. Prepare and submit a first draft Manual for comments and review by DoT. 6. Receive comments from DoT and improve the draft. 7. Submit a second draft for DoT / Stakeholders review. 8. All agencies to attend a workshop to receive comment and thereby improve the draft. 9. Collect comments from the outcome of the workshop and prepare a final manual.

These steps were followed as practical as possible to develop the manual. Since the pavement design manual is special design manual consultation with stakeholders were conducted mainly during the workshops that was held during the project. Also, meetings with consultants developing other manual were held to coordinate the interaction between the pavement design manual and the other manuals.

The DoT instructions from the beginning were to incorporate a mechanistic-empirical method in the new design manual, include new material characterization and add sections for pavement maintenance and life cycle cost analysis. All the Chapters and Appendices of the PDM were developed in complete co-ordination with DoT. An initial table of contents of the topics that expected to be covered in the manual was given by the DoT. Some changes were introduced on the table of content. However, all topics were covered in the developed manual.

The DoT requirements were included in a preliminary report that was submitted to DoT in March 2011. Following this submission a workshop was held in March 2011 to the DoT /Stakeholders. The purpose of this workshop was to present the updated topics and table of contents that will be incorporated in the manual as well as address comments received on the preliminary report.

Once the general outline was set from the workshop the manual development started. All the Chapters and Appendices of the PDM were developed in complete co-ordination with DoT. Several chapters were submitted individually for DoT review during the development process. The following sections will cover the document development and the consultation with the DoT.

3 BACKGROUND AND HISTORY Historically, pavement design had been based on empirical models formulated from pavement test tracks or lab testing. These empirical methods use nomographs and simple equations to obtain the layers thickness. While these nomographs were developed using limited data, the issue that had faced many agencies is when the conditions extend beyond the nomograph limits, is the resulting thickness acceptable from an economical and safety viewpoints or not.

There had been a huge advance in the technology which led to the easiness to perform complicated computations using computer. At the same time, there had been a significant increase in the traffic loads, traffic counts, advance in material characterization and better modelling of the environmental factors. Accordingly, agencies started looking into using mechanistic empirical (M-E) methods that is based on fundamental properties and advanced material characterization to better design economical pavement structure.

Countries around the World either use a method that was developed locally or adopt an international method but modify it to the country local condition. The manuals that were considered for the pavement design manual were the following:

1. A Guide to Structural Design of Road Pavements Austroads Australia and New Zealand.

2. South African Mechanistic Pavement Design Method South Africa 3. American Association of State Highway and Transportation Officials. Mechanistic-Empirical

Pavement Design Guide (MEPDG) USA. 4. Asphalt Institute Thickness Design Guide MS-1 5. Shell Oil Methodology UK. 6. American Association of State Highway and Transportation Officials. Guide for Design of

Pavement Structures (1993) USA. 7. Abu Dhabi Municipality (ADM) pavement design manual 8. Dubai Pavement Design Manual 9. Saudi Arabia Pavement Design Manual 10. Qatar Pavement Design Manual

The first 4 methods are mechanistic-empirical methods that are based on fundamental material characterization and mechanistic analysis of pavement structure. While the remaining methods are empirical methods developed from test tracks and lab testing analysis. Qatar PDM provides a catalog type of pavements design manual in which a pavement section can be selected based upon allowable traffic and foundation conditions.

These listed manuals were studied and evaluated for the Abu Dhabi. ME methods are based on similar concepts with different models development. Accordingly, it was decided to rely on only one empirical method and one ME method. The 1993 AASHTO was selected for the empirical method because all agencies and clients are familiar with this method. 1993 ASSHTO guide has been used for long time in Abu Dhabi as the base for Abu Dhabi Municipality Roadway Design Manual. While, Austroads was selected for the M-E method because the models used in Austroads were developed for similar climatic conditions to Abu Dhabi. In addition to these two main manuals Abu Dhabi Municipality Roadway Design Manual referenced to obtain inputs that was set for Abu Dhabi and is common to all pavement designers.

4 BASE DOCUMENTS The three manuals selected for the new Abu Dhabi pavement design manual were:

1. A Guide to Structural Design of Road Pavements Austroads Australia and New Zealand.

2. American Association of State Highway and Transportation Officials. Guide for Design of Pavement Structures (1993) USA.

3. Abu Dhabi Municipality (ADM) pavement design manual This section gives a general overview and summary to these manual.

4.1 1993 AASHTO Empirical method The 1993 American Association of State Highway and Transportation Officials (AASHTO) Guide for Design of Pavement Structures is based on empirical method. Most countries around the world use the 1993 AASHTO guide with some modification to reflect local experience and conditions. Abu Dhabi Municipality Roadway Design Manual, which is based on the 1993 AASHTO guide, is an example.

To develop the Guide for Design of Pavement Structures, AASHTO compiled results from road tests conducted from 1958 to 1960 in Ottawa, Illinois, U.S.A. Data from these tests reflect one climatic condition, one foundation type, and one million equivalent single axle loads (ESALs). From 1960 to 1993, AASHTO added several enhancements, such increased reliance on traffic data and a limiting layer approach.

Covering both flexible and rigid pavement design, The 1993 AASHTO Guide describes material characterization, equivalent traffic estimation, life cycle costs, and existing pavement evaluation. It applies an ESAL as the basic unit for traffic estimation. Its material characterizations use an empirical factor to reflect layer stiffness.

Pavement designers around the world have used this guide successfully for many years. Reasons for designers success with this guide include the following:

1. Pavement designers can easily use the Nomograph or software. 2. Inputs defined by the guide are simple, many of which can be assumed easily. 3. Designers are very familiar with the methodology.

4.2 Austroads Mechanistic-empirical method Advances in technology have encouraged the pavement community to start shifting from the empirical method to the M-E method, which is based on fundamental material properties and actual traffic loads.

Applying the fundamental stresses and strains of the materials in different layers at different depths of the pavement structure, the mechanistic method enables designers to evaluate the validity of proposed layer thicknesses. Designers calculate stresses and strains using either linear elastic analysis or a more complicated model that focuses on finite elements under actual traffic loads. Analysis using the mechanistic method also depends on detailed material characterizations, which vary based on temperature (for hot mix asphalt layers), ground water table depth, and moisture

content (for granular layers). All M-E methods involve using a software package to analyse and design the pavement structure.

Austroads, the association of Australian and New Zealand road transport and traffic authorities, has developed an M-E pavement design guide, Guide to Pavement Technology, Part 2: Pavement Structural Design. This manual contains ten different sections that cover all aspects of pavement design, including structural design, surfacing, materials, pavement evaluation and treatment, maintenance, construction work practices, and drainage. Austroads also has a software package for pavement analysis.

According to the Austroads guide, engineers apply structural analysis of the trial pavement configuration to quantify critical strains and stresses that are caused by traffic loads. They can vary the method to consider pavement layers as either fully elastic (viscoelastic), uniform in lateral extent, or variable, with either full friction or no friction between the layers. By using these variations, engineers attempt to establish theoretical estimates that agree with observed reactions to traffic loading.

In addition, engineers can analyse pavement designs based on varying traffic loads, from a single vertical load with uniform tire contact stress to multiple loads with multi-directional components and non-uniform stress distribution. They can also vary traffic speeds to further assess potential traffic loads. Engineers must be careful, however, to ensure that the sophistication of the analysis method is compatible with the quality of the input data. Otherwise, they need to make too many assumptions to fill the gaps, resulting in misleading, if not worthless, analysis.

Austroads states that engineers can reliably obtain required input for analysis based on the M-E method. Results from such analysis provide predictions of pavement performance that reasonably match pavement performance in Australasian.

Upon completing the structural analysis, engineers can use the results to estimate the allowable loading of the pavement configuration. Austroads states that, in the M-E method, most performance criteria assigned to pavement materials and to the subgrade relate the level of strain induced by a standard single axle load and the number of such loads that exceed the pavements tolerance level, based on material characteristics.

Figure 1 Mechanistic-Empirical Design Method Flowchart

4.3 Abu Dhabi Municipality Pavement Design Manual Abu Dhabi Municipality (ADM) pavement Design Manual was developed based on the 1993 AASHTO Guide for Design of Pavement Structures. The inputs required for the pavement design had been tailored for local conditions. ADM follows deep strength concept in pavement design. Using inputs from ADM manual in the 1993 AASHTO guide will provide pavement structure with thicker asphalt concrete layers. ADM also imposed minimum layer thickness for each road category to meet the standard specifications and mixture requirements available locally.

Traffic Foundation Climate Material Properties

Trial Section

Pavement Analysis Performance Criteria

Project Reliability

Comparison of Designs

Viable Design

Select Design

Inputs

Analysis

Selection

Accept No

Yes

5 SCOPE OF MANUAL 5.1 Application of this manual Information in this manual focuses on structural pavement design, with methods for determining layer thickness and pavement structural capacity. This manual is intended for use by pavement engineers conducting structural design for either existing or new pavement structures.

Structural calculations for pavement design require knowledge of existing traffic flow, predictions of anticipated future traffic, and environmental factors at the roads location. Pavement designers must also obtain information about the properties of the materials (such as asphalt, Portland cement, or granular road base) that will be used in each pavement layer. Designs must account for these material properties in conjunction with the material specifications and asphalt mixture designs, as detailed in the Abu Dhabi DoT Standard Specifications for Road Works manual.

Completing the pavement design process involves using either the 1993 AASHTO nomograph or Austroads software to determine the required layer thickness. After generating several design options using different methods, a pavement engineer shall conduct an LCC analysis to compare the designs for cost effectiveness. For details about LCC analysis, refer to Chapter 9, Life-cycle Cost Analysis, in this manual, as well as the Abu Dhabi DoTs Project Cost Estimating and Standard Bill of Quantities manuals.

Pavement design requires not only designing new pavements, but also evaluating existing pavement. Ensuring that existing pavement facilities have sufficient functional capacity and ride quality involves maintenance, possibly including the construction of additional layers. Optional methods for maintaining existing pavements include chip sealing, fog sealing, slurry sealing, and crack sealing. Such maintenance or rehabilitation requires accessing the pavement condition surveys database, which is part of the Abu Dhabi DoTs pavement management system, to get information about the condition of the existing pavement. Refer to Chapter 10, Pavement Management Systems, in this manual for information about the pavement management system and Chapter 11 for the existing pavement evaluation and pavement condition surveys.

Evaluating existing pavements requires significant engineering judgement and effective application of the backcalculation procedure. Based on the pavement design guidelines in this manual, design engineers apply their own methodologies and experienced judgment to arrive at final rehabilitation methods.

This manual provides guidelines for the design of new and rehabilitation of asphalt and concrete pavements. The concrete pavement design guidelines are given in less detail. Applicable international standards for concrete pavement design are followed in the manual.

5.2 Content and format This manual includes sections detailing inputs such as traffic, climate, and material properties, as well as sections on maintenance, rehabilitation, and LCC analysis. It also provides appropriate charts and nomographs. The section on low-volume roads is particularly relevant for rural areas.

Because different design methodologies deal with inputs in different ways, this manual advises designers on how to estimate these inputs and how to obtain valid condition inputs for Abu Dhabi. It also includes ways to ensure that pavement designs support sustainability.

This manual includes the following chapters:

Chapter 1 Introduction: Outlines the purpose, scope, intended users, and application of this manual.

Chapter 2 Pavement design components: Describes elements, such as environmental and traffic factors, that must be considered in pavement design, and provides instructions on how to determine such factors.

Chapter 3 Pavement material characterization: Identifies properties of pavement materials and provides instructions on how to determine such properties through tests of the use of models.

Chapter 4 Pavement rehabilitation: Details the rehabilitation of flexible and rigid pavement structures.

Chapter 5 Rigid pavement design: Details the design of new flexible and rigid pavement structures.

Chapter 6 Low-volume roads: Covers the design of low-volume roads. Chapter 7 Drainage design: Focuses on the design of granular drainage layer in a

pavement structure. Chapter 8 Flexible pavement maintenance: Offers different maintenance options. Chapter 9 Life-cycle cost analysis: Details LCC analysis for pavement structures. Chapter 10 Pavement management systems: Provides an overview of the Abu Dhabi

PMS and summarises related concepts. Chapter 11 - Existing Pavement Evaluation: Provides overview of different methods to

conduct pavement condition surveys and how to analysis the collected distress data.

The appendices of this manual provide supplementary charts and tables for the design on the rigid pavements.

6 DOCUMENT DEVELOPMENT The development of the manual document required progress meeting with DoT and Aurecon, submission of separate chapters for early review, and meetings with DoT and other consultants. The Table below includes the dates of meetings and presentations held during the progress of the manual development.

The overall Schedule for Parsons International Limiteds completion of the Pavement design manual is shown on the schedule included in PILs Project Management Plan (PMP). The key milestone dates for the delivery of the Pavement Design manual are as follows.

Preliminary Study and List of Contents: 10 March 2011 First workshop 14 March 2011 Completion of Stakeholder Review: 31 March 2011 Delivery of First Draft Document: April 2012 Completion of DOT Reviews July 2012 Submission of Draft Document: September 2012 Second Workshop: 12 November 2012 Final Comments: 01 December 2012 Final Draft Document: February 2013 Final Document: 01 May 2013

6.1 Progress meetings Monthly progress meetings were being held with DoT and Aurecon to update on the progress of the manual development. The progress meeting were attended by the Parsons Project Director. Progress and information presented in these meeting were collected from each manual lead developer.

6.2 Consultation meetings The progress meeting were mainly on the project management level not on the technical level. Several technical meetings were held with the DoT pavement design manual lead reviewer (Dr. Salim Sulaiman). Also, meetings were held with other consultants (TrafQuest and Halcrow) developing other manual to discuss interaction between the pavement design manual and these manual. The manuals that had interaction with pavement design manual were the Geotechnical Investigation and Design Guidelines developed by Halcrow and the Road Performance Manual by TrafQuest.

In mid December 2012, a meeting was held at the DoT with DoT, Aurecon and the Getechnical investigation manual developer (Halcrow). The outcome of this meeting was to add a new section in the pavement design manual to cover the evaluation of the existing pavement structures.

6.3 Formal submission All the Chapters and Appendices of the PDM were developed in complete co-ordination with DoT. The initial plan was to submit chapter by chapter to the DoT lead reviewer. This plan was followed for the first few chapters that were submitted individually for DoT review. However, due to the interaction between different chapters and complication of the manual, all chapters were submitted together as a first complete draft.

The first complete draft of the PDM was delivered for review in April 2012. The document has been subject to rigorous review during several meetings with DoT lead reviewer and DoT reviewer panel. The comments obtained from this first review were addressed in a second draft.

The second full draft of the document was delivered for review in September 2012. The second draft was distributed to the Stakeholders for their review. Initial comments from Aurecon reviewers were send on the second draft. Comments that were received for the Pavement Design Manual are listed in Appendix A.

In November 2012 a workshop was held for all agencies to present the draft final and collect their comments. After the presentation additional comments were received from the Stakeholders mainly Al-Ain Municipality. All comments were addressed and included in the final document.

In mid December 2012 after meeting with DoT and other manuals developer a new chapter on the evaluation of the existing pavement structures was requested to be added. Initially, this new section was added as an appendix and in February 2013 the final draft manual was submitted.

Then the DoT requested that it should be added as a new chapter to the main text which was done in the final version that was submitted in beginning of May 2013.

6.4 Workshop Two workshops were given during the project; the first was given in March 2011 to discuss the initial outline of the manual. The second workshop was given on November 12th 2012. The second workshop presented the final developed manual. The workshop discussed the new features and methods described in the pavement design. A design example using the empirical and the M-E method was presented to compare the two methods. The presentation given during the second workshop is included in Appendix B.

6.5 Comment Review The comments received from the DoT / Stakeholders were reviewed carefully. Most of the comments incorporated in the pavement design manual. None of the comments was major due to the coordination with the DoT lead reviewer throughout the manual development.

The few comments that were not included require the standardization of certain inputs to the design process. The standardization of certain inputs would disagree with one of the main requirement of the manual that it should be applicable to all clients and projects. The standardization can be done individually by local agencies to accommodate their local requirements.

6.6 Final submission The final document was updated with the final format that was request by the project manager (Aurecon). The cover and back pages were added to the PDF file. A final version was submitted in May 2013.

The following table list the technical meeting held during the development of the PDM.

Table 1 Technical Meetings Information

Date Title Agenda Attendees

20-Feb-11 PDM Preliminary report

Discussion of the Preliminary report and manual outline

Dr. Salim Suliman (DOT), Dr. Rasin Mufti (PIL), Dr. Walid

Nassar (PIL)

10-March-11 PDM Preliminary report

Discussion of the Preliminary report and preparation for the

first workshop

Parviz Djahani (DoT), Dr. Salim Suliman (DOT), Willie Victor

(Aurecon), Dr. Rasin Mufti (PIL), Mohamed Elbasyouny (PIL)

05-April-11 PDM Workshop comments

Updated outline, schedule and the comments received

on the PDM during the workshop

Dr. Salim Suliman (DOT), Dr. Rasin Mufti (PIL), Mohamed

Elbasyouny (PIL)

08-June-11 PDM progress meeting

Discuss comments on Chapters 1,2,and 3

Dr. Salim Suliman (DOT), Dr. Rasin Mufti (PIL), Mohamed

Elbasyouny (PIL)

14-June-11 PDM and RPMS Manual Discuss interaction between

PDM and RPMS Manual

Rob Hranac (TrafQuest), Mohamed El-Basyouny (PIL),

Ahmed Abdel Dayem, (Trafquest)

15-September-

11 PDM progress

meeting Progress in PDM Dr. Salim Suliman (DOT), Dr. Rasin Mufti (PIL), Mohamed

Elbasyouny (PIL)

06-June-12 PDM Review Comments of PDM First Draft Dr. Salim Suliman (DOT), Dr.

Nabil Salman (DoT), Dr. Rasin Mufti (PIL), Mohamed

Elbasyouny (PIL)

12-June-12 PDM Review Comments of PDM First Draft Dr. Salim Suliman (DOT), Mohamed Elbasyouny (PIL)

19-December-

12

Meeting on Pavement

Condition Survey

Discuss location and content of Pavement Condition

Survey

Parviz Djahani (DoT), Dr. Salim Suliman (DOT), Jihad Sawan

(DoT), Abdulla Al Shaibani (DoT), Willie Victor (Aurecon),

Andrew Harley (Halcrow), Mohamed Elbasyouny (PIL)

7 ACKNOWLEGMENT This document was developed by Parsons International Limited. The document consultants would like to express their personal thanks and gratitude to:

Dr Parviz Djahani: For overall leading and steering of the project. Dr. Salim Sulaiman (DoT Review Committee Lead): For his clear and thoughtful guidance throughout the development of PDM.

Willie Victor, For his time and support during the project progress. Members of the DoT review Committee For their time and input to aid the development of the PDM.

All remaining stakeholders :For having shared their thoughts, comments and ideas to develop the PDM.

Parsons Staff:

Dr. Rasin Mufti, Project Director Dr. Mohamed Elbasyouny, manual lead author Eng. Sohila Bemanian, maintenance author Eng. Keith Hixson, drainage author Dr. Walid Nassar, peer reviewer Eng. Ramesh Vishwakarma, rigid pavement author Gaylin Gardette, editor Ron Manns, editor Abdul Vasid, Cad designer

APPENDIX A: COMPILED COMMENTS FROM DOT/ STAKEHOLDERS This appendix provides the comments received for the Pavement Design Manual draft final version by December 2012.

A14 Document Title: Deliverable Ref: A14.12Title of Interim Deliverable: Second Draft Document

MAN-000540 Revision No: 3 Dated: #################### ACONEX Document No. of Approved Content Outline:

Geometry #################### Due Date for Initial Responses:

Priorities: High Priority (H):

Medium Priority (M):

Low Priority (L):

Priority(H,M,L)

1 Bus stops Bus stop pavement area should be laid with bitumen modified red colored asphalt wearing course.

M DOT-Public Transport Division

Added to Roads Specification manual

2 Par 1.4 Content and Format Page 3 Chapter 8 - Flexible pavement maintenance: Change "offers" to "Offers"

L Johan Calitz Aurecon Docment Reviewer

Corrected

3 Par 1.5.1Flexible pavements Page 4 In second paragraph change "contactors" to "contractors" L Johan Calitz Aurecon Docment Reviewer

Corrected

4 Par 2.1 Overview Page 9 First paragraph. Careful study and characterization of these factors is Change "is" to "are"


Corrected

5 Par 2.2 Environment Page 9 Environment includes a many variables. Omit "a". L Johan Calitz Aurecon Docment Reviewer

Corrected

6 Figure 2-2 Page 12 Cannot read some rainfall figures H Johan Calitz Aurecon Docment Reviewer

Corrected

7 Table 2-1 Page 12 Start table on next page to fit the whole table on 1 page M Johan Calitz Aurecon Docment Reviewer

Corrected

8 Paragraph 2.3.2 Vehicle classification

Page 16 Vehicle classifications on paragraph 3 should start with numbering 1 and not 7 to be similar to numbering in Figure 2-4 on page 17

M Johan Calitz Aurecon Docment Reviewer

Corrected

9 Paragraph 2.3.10 Truck factor and Paragraph 2.3.11 Equivalent axle load factor

Page 21 and Page 22 These paragraps should be changed around because the method to calculate EALF used in equation 2-9 in paragraph 2.3.10 is only provided in paragraph 2.3.11


Corrected

10 Paragraph 2.3.11 Page 22 Last sentence of first paragraph: "As an alternative method, can apply .." Add "designers" before "can apply"


Corrected

11 Chapter 3 Pavement Materials Page 25 Second paragraph. Add "a" to "Pavement is composed of .." L Johan Calitz Aurecon Docment Reviewer

Corrected

DDC Response

Observations such as typographical errors which may be corrected during next revision.

No Subject Page / Section No Reviewers Comment Reviewer Reviewer's Organization

Sub-Package Name: Geometry 2Comments that will cause the document to be unacceptable.Comments which require the document to be revised and resubmitted.

Package Name: Consolidated Comments Submitted to DDC:

UNIFYING AND STANDARDIZING OF ROAD ENGINEERING PRACTICESCONSOLIDATED REVIEWERS COMMENT SHEET

Pavement Design Manual

ACONEX Document No. of Interim Deliverable Reviewed:

Page 1 of 10






Low Priority (L):

Priority(H,M,L) DDC Response








12 Par 3.2.1 Empirical design for granular base and subbase materials

Page 28 Add "The AASHTO Road Test basis of these correlations is" to the second sentence of the second paragraph reading "A granular base of has a layer " Refer to page II-17 and II-20 of 1993 AASHTO Guide for Design of Pavement Structures


Corrected

13 Figure 3-1 Page 29 This figure copied from the AASHTO manual page II-19 should be revised so that the footers which include AASHTO manual references are not shown.


Corrected

14 Figure 3-1 page 29 The title of this figure is on the page following the figure and should be moved to the bottom of the figure on page 29


Corrected

15 Par 3.2.1 Empirical design for granular base and subbase materials

page 30 Add "In the AASHTO Road Test the basis of these correlations is" to the second sentence of the paragraph reading " Granular subbase has a base layer " Refer to page II-20 of 1993 AASHTO Guide for Design of Pavement Structures


Corrected



Corrected

17 Par 3.2.2 Mechanistic design for granular base and subbase materials

Page 32 Change the last sentence of the third paragraph to: "The top half of Table 3-2 is applicable for granular material that has a CBR greater than 30%." Refer Table 6.4 on page 52 of Austroads manual.


Corrected

18 Par 3.3 modified granular materials Page 33 Last sentence of first paragraph : Change "stabilised" to "modified" in the sentence "Austroads specifies that stabilised granular materials ". Refer page 53 Autroads Manual


Corrected



Corrected

Page 2 of 10






Low Priority (L):











Corrected

21 Par 3.5.1 Empirical design for asphalt concrete materials

Page 38 Change the second paragraph to the following: "The structural coefficient of AC varies between 0.2 and 0.44 and AC with a layer coefficient of 0.44 (per inch), corresponds to an AC resiient modulus of 3.1 Gpa (450,000 psi)" Reference AASHTO manual page II-17


Corrected

22 Par 3.5.2 Mechanistic design for asphalt concrete materials

Page 41 First bullet " modulus of the bitumen" Second bullet. "percentage bitumen in the asphalt.." Directly from Austroads manual page 71. This is the convention used in AAHTO and Austroads design manuals. In this design manual the authors used aphalt binder and asphalt concrete.


Corrected

23 Figure 3-7 Page 42 Change "asphalt" in title to "asphalt concrete". Refer Austroads figure 6.10 page 71


Corrected

24 Figure 4-3 Page 55 Change "Foundatio" to "Foundation" and "Climat" to "Climate". Refer Austroads page 97.


Corrected

25 Par 4.2.2.3Determination of a granular base layer's elastic parameters

Page 58 First paragraph. Change "because" to "Because" L Johan Calitz Aurecon Docment Reviewer

Corrected

26 Par 4.3.2 Empirical pavement design Page 61 Second parapraph. Reference is made to Appendix C for design traffic calculation procedure. Appendix C on page 202 contains AASHTO slab thickness design tables. Correct reference.

H Johan Calitz Aurecon Docment Reviewer

Corrected

27 Par 4.3.3.2Determine required structural design

Page 67 First paragraph. "Refer to section X.". Provide correct reference H Johan Calitz Aurecon Docment Reviewer

Corrected

28 Par 4.3.3.2Determine required structural design

Page 67 - 69 Please provide reference to the design figures: Figure 4-6, Figure 4-7, Figure 4-8 and Figure 4-9. Could not be found in AASHTO or Austroads Design manuals


Corrected

Page 3 of 10






Low Priority (L):









29 Par 4.3.4 Joint details Page 70 Change "joint" to "joints" in first paragraph L Johan Calitz Aurecon Docment Reviewer

Corrected

30 Par4.3.5.1Rigid pavement types Page 72 Third sentence of first paragraph. Change "LPCP" to "JPCP" L Johan Calitz Aurecon Docment Reviewer

Corrected

31 Equation 4-10 Page 73 Provide details for the symbols used in equation as in Austroads manual page 127. Note that according to Austroads manual the maximum value for subgrade CBR determined according to this method is 15%.


Corrected

32 Equation 4-11 Page 74 Change "Designers shall use Equation 4-12.." to "Designers shall use equation 4-11.." in the line below the equation. Refer Austroads Manual page 130, equation 9.2


Corrected

33 Equation 4-12 Page 74 Change title of Equation 4.12 to "Allowable axle load repitions when stress (Sr) is between 0.45 and 0.55." Refer Autroads manual page 130 equation 9.3


Corrected

34 Equation 4-12 Page 75 Change "designers shall use Equation 4-13.." to "designers shall use equation 4-12.." in the line below the eqation. Refer Austroads Manual page 130, equation 9.3


Corrected

35 Equation 4-13 Page 75 Change title of Equation 4-13 to: "Equivalent Stress for use in equations 4-11 and 4-12". Refer Austroads manual page 130


Corrected

36 Par 4.4.3 Construction procedure Page 78 Recommend that the use of stabilised layers beneath interlock paver blocks be mentioned. Also bedding sand layer thickness of 50 mm might be changed to 25 to 50 mm.


Added

37 Par 4.4.4.1 Design factors Page 79 Change "The Four .." to "The four " in the first paragraph L Johan Calitz Aurecon Docment Reviewer

Corrected

38 Par 5.4.2 Functional evaluation of existing pavement

Page 93 In the third bullet change "Refer to table 4-1 .." to "Refer to Table 5-1 .."


Corrected

Page 4 of 10






Low Priority (L):









39 Par 5.5.6 Mechanistic design Page 102 Reference should be made to Austroads Guide to Pavement Technology Part 5: Pavement Evaluation and Treatment Design


Corrected

40 Par 8.4 Pavement preservation treatments

Page 144 Recommend that paragraph 8.5 Preservation Treatments be placed before Paragraph 8.4 Pavement preservation treatments. The reason being that the individual treatments mentioned in paragraph 8.4 are discussed in detail in paragraph 8.5.


Corrected

41 Table 8-2: Pavement treatments and Table 8-3 Pavement treatment cost and expected life

Page 147 and page 148

Abbreviation "CIR" for cold in place recycling is used in comparison with pages 136, 137 and 155 where the abreviation "CIPR" is used. Recommend change to "CIPR" in these tables.


Corrected

42 Profile milling, cold in place recycling, Hot-in -place asphalt recycling, Full-depth asphalt repair (patching)

page 155 to page 157 These paragraphs should be numbered 8.5.2.6 ; 8.5.2.7; 8.5.2.8; 8.5.2.9 respectively


Corrected

43 Hot -in-place asphalt recycling page 156 In the third paragraph mention is made of adding "bitumen". This is the Australian and American thermodology which is used worlwide. In this manual "bitumen" is called "asphalt".


Corrected

44 Par 9.4 LCCA example page 171 The first line reads:"Figure 9-5 shows a step- by -step process" This is not correct because Figure 9-5 is a photo of a highway.


Corrected

45 Appendix A: Developing Effective Modulus of Subgrade Reaction

page 185 The first paragraph says "This appendix provides an excerp from the 1993 American Association of State " This exerp is not as on page ii-37 par 3.2.1 of the 1993 AASHTO manual. The reference should be corrected


Corrected

46 Cited References page 220 Add Austroads: Guide to Pavement Technology, Part 5: Pavement Evaluation and Treatment Design. Synney Australia: Austroads Incorporated, 2008. 978-1-921551-22-2


Added

47 Glossary Glossary to be added M Johan Calitz Aurecon Docment Reviewer

Added

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1 Traffic Projections /2.3.6

Please include rational growth rate for major town(example Al Ain, Abu Dhabi, western region, any other major city area) based on the latest studies (steam model 2015etc) conducted by the transport agencies to enable the designer to have fair assumption to predict future traffic.

LAl Ain Municipality Al Ain Municipality

This is included in the traffic manual

2 Equivlent Axle load factor /2.3.11

IT will be better if we used Standard axel load from GCC truck manufacturing specification, or the truck weight that adopted by DOT to defined standard axel load that used in UAE. Also consider different type of busses and their standard axle load factor for each one seperately


PDM is general manual however, clients need to include local axles.

3 Modified granular material /3.3

Provide extract of the specification for modified granular material, percentage of cement, lime to be added, expected stiffness, indirect tensile strength, other properties etc.

MAl Ain Municipality Al Ain Municipality

added

4 Stabilized material /3.4.2Provide Figure showing the relationship between indirect tensile strength, field stiffness of stabilized material with layer coefficient.


There are many relationships and none is recommended

Page 6 of 10






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5 Recycled Material /3.8

There is no Design guide line provided in the manual for the use of recycled pavement material for rehabilitation of pavement structure. In fact most part of the world these techniques have been adopted long ago. As the Abu Dhabi Emirates mandates to use sustainable design technique, the manual should have more emphasized on these techniques by providing design guideline, design example. Furthermore this chapter should be expanded by taking into consideration of case studies.


Added but more information is included in the specification manual

6 Recycled Material /3.9.4 Include Methodology for Cold In situ Recycling with form bitumen, foamed asphalt mixes. M

Al Ain Municipality Al Ain Municipality

Added in the maintenance chapter

7 Interlocking Pavers DesignThe manual does not provide guideline for heavy duty interlocking pavers design. The information provided under this section is bare minimum.


PDM is not entended for heavy duty such as in airport. General guideline for regular interlocking pavers is given

8 Interlocking Pavers Design

Layer coefficient for, Concrete paver, sand bedding considered in the example (section 4.4.4.1, paragraph 3) is incorrect as per the table 4-3.Layer coefficient for sand bedding cannot be the same as Asphalt and table 4-3 does not provide layer coefficient for concrete paver as well.

HAl Ain Municipality Al Ain Municipality

reference added. However, this is an approximation that was recommended by ICPI

Page 7 of 10






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9 Unbound Granular material /6.3.2

The last paragraph of the above section states that the minimum CBR for the sub base is 65%.But sub base, CBR 60% material used in Al AIn , Similarly, Sub-base with CBR 30% used in Dubai. Therefore please provide reference to the above requirement to justify.


added

10 Pavement treatment cost and expected lifeThe Manual should use the cost inputs based on the local condition rather than referring to US condition. M


Modified as possible

11 Pavement treatment cost and expected lifeThe envinmental impact should be considered for the cases, Alternatives 1 &2 L


The proposed method does not include the envirnmental effect.

12 Cited references General Comment

The manual is more biased towards American Standards. The author did not refer important design guidelines adopted in the other developed countries standards. The Author should also refer other standards as well while compiling comprehensive documents. Example .For heavy duty paving block design Author should refer BS 7533-1:2001 which provide comprehensive design guideline. Similarly, Recycle Asphalt pavement design (Cold in situ recycling/ Hot in place recycling as stated in the life cycle cost example) no design guideline provided. Author could have referred other standards adopted in the developed countries


The manual covers Austrailian as well as American standards

Page 8 of 10






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13 Pavement Design Check list General CommentProvide check list sheet that include requirements information for the pavement design to assess designer in revising pavement design documents


This would differ from one client to the other and each should have his own requirements.

14

Emperical Pavement Design Example /4.5Provide detailed example for pavement design using M-E method M


Provided and added to chapter 4.

1 Pavement Design Manual

Traffic requires more details on Traffic count and axle configurations

Dr.Salim/ Dr. Nabel DOT

addressed in the final version

2 Pavement Design ManualAdd Examples Dr.Salim/ Dr. Nabel DOT

added

3 Pavement Design ManualTechniques for Stabilization and Material selection Dr.Salim/ Dr. Nabel DOT

added

4 Pavement Design ManualMore details on Pavement Management Systems Dr.Salim/ Dr. Nabel DOT

This would be covered in the management manual


Maintenance chapter need to include diagnostic and methods


added chapter on pavement evaluation


Graphics throughout the manual need to be improved and made clearer.


All graphs are fixed


Add Chapter on over-weighted trucks and up-normal loads damage to pavement



Add section on analysis and data interpretation of Falling Weight Deflectometer (FWD) testing


Added reference but no specific method is added since it will depend on the software used for the backcalcualtions.


Add section on Paver interlocking blocks design use UK


Added

10 Pavement Design ManualAdd sketches for axle types Dr.Salim/ Dr. Nabel DOT

Added


Adjust design lane, % of trucks and other traffic factors.


Corrected

12 Pavement Design ManualCheck equation 2.9 and add example Dr.Salim/ Dr. Nabel DOT

Corrected

Page 9 of 10






Low Priority (L):










Add more details to page 23 and describe traffic wander and other factors listed.


Corrected

14 Pavement Design ManualInclude CBR power model Dr.Salim/ Dr. Nabel DOT

Added


Emphasize that better quality material should be at the top for empirical design.


text is added


Add more details on the Geo-grids functionality and description


Geo-grids specification is added in the specification manual. Geogird impact in pavement design is not proven

yet


Comment on reliability and its impact on structure design


Text updated


Adjust the drainage coefficient to include 1.2 for drainage layers.


Corrected


Adjust Road Classes to reflect Highway classes (Truck route, freeway, expressway, collector and local).


Corrected

Page 10 of 10

APPENDIX B: WORKSHOP PRESENTATION This appendix provides the slides for the presentation given by PIL on the pavement design manual draft final version during the second workshop on 12 November 2012.

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UNIFYING AND STANDARDIZATION OF UNIFYING AND STANDARDIZATION OF UNIFYING AND STANDARDIZATION OF UNIFYING AND STANDARDIZATION OF UNIFYING AND STANDARDIZATION OF UNIFYING AND STANDARDIZATION OF UNIFYING AND STANDARDIZATION OF UNIFYING AND STANDARDIZATION OF

HIGHWAY ENGINEERING PRACTICESHIGHWAY ENGINEERING PRACTICESHIGHWAY ENGINEERING PRACTICESHIGHWAY ENGINEERING PRACTICESHIGHWAY ENGINEERING PRACTICESHIGHWAY ENGINEERING PRACTICESHIGHWAY ENGINEERING PRACTICESHIGHWAY ENGINEERING PRACTICES

Pavement Design ManualPavement Design Manual

Workshop on 12 November 2012Workshop on 12 November 2012

Unifying and Standardization of Highway Engineering Practices

Manuals Developed by Parsons

Geometry 2

Roads and Highway Drainage Manual

Road Landscape Manual


Construction

Standard Specification for Roads and Structures Works

Volume 1 Road Works

Volume II Structure Works

Standard Bill of Quantities

Project Cost Estimating Manual

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Overall Objectives

Unify the approach for preparing BoQ and Cost Estimation for all

Road Projects in the Emirates

Update to recent international standards and practices

Inclusive for all conditions and types of road construction within

the Emirate

Produce high quality manuals and documents that are most

applicable for the longest term possible

Customize Manuals for Abu Dhabi environment utilizing Parsons

local work experience

Objective of Pavement Design Manual Provides detailed guidelines for Pavement Structural

Design, that includes:

Structure Design of Flexible and Rigid Pavements,

New and rehabilitation of pavement structures

Low Volume Roads

Life Cycle Cost analysis

Pavement Maintenance strategy

More details and analysis that require the Engineers

involvement and understanding of traffic, material,

environment and pavement structural design to

provide a sustainable and economical design.

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Preparation Approach and Methodology

Mechanistic Pavement

Design based on Guide to

Pavement Technology Part

2, Austroads, 2008, Australia.

Empirical Pavement Design

based on AASHTO Guide for

Design of Pavement

Structures, 1993, USA.

Other Documents

The manual shall be read in conjunction with the following

documents.

AASHTO Guide for Design of Pavement Structures, 1993

Guide to Pavement Technology Part 2, Austroads, 2008,

DoT Standard Specifications

DoT Roads Drainage Manual

DoT Standard Bill of Quantities

DoT Cost Estimating Manual

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Organization of the Pavement Design Manual

The PD manual is divided into ten different Chapters:

1. Introduction

2. Pavement Components

3. Pavement Materials

4. New Pavement Design

5. Rehabilitation Design

6. Low Volume Roads

7. Drainage Design

8. Pavement Maintenance

9. Life Cycle Cost Analysis

10.Pavement Management System.

Chapter 2 Pavement Components

Environmental

Empirical design correct subgrade modulus using

Relative Damage (Uf)

ME design rainfall for subgrade modulus and

temperature for asphalt modulus

Traffic Analysis

Equivalent Single Axle load 80 kN

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Rainfall

56.3 mm


Weighted mean

annual air

temperature

45.0 C to 38.7 C,

43.5 C

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Traffic Design life

Vehicle classification

Axle group configuration

Tire pressure

Vehicle count

Traffic projections

Design lanes

Directional factor

Percentage of trucks

Truck factor

Equivalent axle load factor

ESAL calculation


Axle Group type Load (kN) Single axle, single tire 53 Single axle, dual tire 80 Tandem axle, single tire 90 Tandem axle, dual tire 135 Tridem axle, dual tire 181 Quad axle, dual tire 221

Design Method Load Damage Exponent (m)

Empirical 4 Mechanistic Control Fatigue 5 Mechanistic Control Rutting 7

EALF = (L/SL)m

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Chapter 3 Pavement Materials

Material Characterization for pavement layers:

Subgrade

Subbase/Base

Cement Stabilized

Asphalt concrete

Plain concrete

General information on;

Geotextile and geogrid

Recycled Materials

Warm Mix Asphalt


Subgrade Soils

Mr = 10 * CBR CBR < 20% (Empirical)

Mr = 2555 * CBR0.64 CBR > 20% (Empirical)

Log CBR = 2.494 - 1.131 log (DCP) (ME)

Back calculations Using Falling Weight

Deflectometer testing (ME)

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Aggregate Base Material

a2 = 0.249(log10EBS) - 0.977 (per inch) (Empirical)

a3 = 0.227(log10ESB) - 0.839 (per inch) (Empirical)

Mr Testing (ME)

Default Values (ME)


Cement Stabilized Material

a2 = 0.25 (Empirical)

28 days Unconfined Testing (ME)

Default Values (ME)

PropertyLean Mix

Concrete

Base 4-5%

cement

Subbase

quality

crushed rock

2-4% cement

Subbase

quality

crushed rock

4-5% cement

Range of Modulus (MPa) 5000-15000 3000-8000 2000-5000 1500-3000

Typical Modulus (MPa) 7000 5000 3500 2000

Degree of anisotropy 1 1 1 1

Range of Poissons ratio 0.1-0.3 0.1-0.3 0.1-0.3 0.1-0.3

Typical value of Poissons ratio 0.2 0.2 0.2 0.2

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Asphalt Concrete Materials

a1 = 0.44 (Empirical)

Asphalt Modulus testing (ME)

Shell Nomograph based on temperature, binder

and loading time (speed) (ME)

Chapter 4 New Design

Flexible, Rigid pavements

Interlocking pavers Blocks design

Empirical Design Based on 1993 AASHTO

Mechanistic Design Based on 2008 Austroads

(requires CYCRLY software)

Step by Step is given.

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Chapter 4 New Design - ME

Traffic Foundation Climate Material Properties

Trial Section

Pavement AnalysisPerformance Criteria

Project Reliability

Comparison of Designs

Viable Design

Select Design

Inputs

Analysis

Selection

Accept No

Yes

Chapter 4 New Design - ME

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Rigid Pavement

Empirical Design Based on AASHTO

Mechanistic Design Based on 2008 Austroads

(requires CYCRLY software)

Joint details is given

Dowels and tie bars design

Chapter 5 Rehabilitation

Important consideration

Pre-overlay repair

Milling

Recycling

Structural or functional overlay

Pavement Evaluation structural Capacity

Empirical overlay design 1993 AASHTO

ME overlay design 2008 Austroads

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Chapter 5 Rehabilitation - Investigation

Cause of Rutting Layer(s) Causing

Rut

Solution

Total pavement thickness

inadequate

Subgrade Thick overlay

Unstable granular layer due to

saturation

Base or subbase Remove unstable layer

over thick overlay

Unstable layer due to low shear

strength

Base Remove unstable layer or

thick overlay

Unstable AC mix (including

stripping)

Surface Remove unstable layer

Compaction by Traffic Surface, base,

subbase

Surface milling and/or

levelling overlay

Studded tire wear Surface Surface milling and/or

levelling overlay

For Example


Distress Type Required Repair

Alligator cracking Repair all high-severity alligator cracking.

Repair medium-severity cracking, unless using reflective

crack control or paving fabric.

Remove soft subsurface material.

Linear cracks Patch high-severity cracks.

Fill linear cracks greater than 0.25 inch with sand-asphalt

mixture or crack filler.

Apply reflective crack control for transverse cracks with

significant opening and closing.

Rutting Apply milling or place a levelling course to remove ruts.

Investigate which layer caused any severe rutting.

Surface irregularities Investigate depressions, humps, ad corrugations; apply

treatment as necessary, which typically involves removal

and replacement.

Repairs needed before overlay

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Structural Evaluation

Visual Survey and material testing

Nondestructive Testing (NDT)

Estimation of Remaining surface life


ME Overlay Design

Similar to New design

Evaluate Existing layer properties

Assume existing layers are fully cracked (no

remaining life)

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Chapter 6 Low Volume Roads

LVR Traffic is less than 1 million ESAL

Asphalt or Aggregate surfaced roads

Only 1993 AASHTO design

Lower Level of inputs

Aggregate surface treatment for stabilization

Asphalt treated

Cement treated

Minimum AC thickness of 60 mm.

Chapter 8 Pavement Maintenance

Distress Identification and Treatment options

Linked to Pavement Management System

Why Routine Maintenance

Extend Pavement service life

Reduce cost no major reconstruction

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Distress identification FHWA Distress Manual

3.1.1 Fatigue (alligator) cracking 3.1.2 Bleeding 3.1.3 Block cracking 3.1.4 Corrugation and shoving 3.1.5 Depression 3.1.6 Joint reflection cracking 3.1.7 Longitudinal cracking 3.1.8 Patching

3.1.9 Polished aggregate 3.1.10 Potholes 3.1.11 Ravelling 3.1.12 Rutting 3.1.13 Slippage cracking 3.1.14 Stripping 3.1.15 Transverse (thermal) cracking 3.1.16 Water bleeding and pumping 3.1.17 Edge Cracking


Treatment options and costPavement Treatments

1. Do nothing 2. Crack seal/fill 3. Fog seal 4. Scrub seal (broom seal) 5. Slurry seal 6. Chip seal 7. Microsurfacing 8. Micro-mill 9. CIR 10. HIPAR 11. Thin hot mix overlay 12. Patching 13. Thick overlay 14. Full-depth reclamation 15. Total reconstruction

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Chapter 9 Life Cycle Cost Analysis

Based on FHWA LCCA

Steps:

Establish alternatives

Determine an analysis period

Determine a discount rate

Determine maintenance and rehabilitation frequencies

Estimate costs

Calculate life-cycle costs

Analyze LCCA results


Treatment Expected Life (Years) 1) 50 mm overlay 7-10 2) 50 mm mill and overlay 10-15 3) Scrub seal 2-5 4) Slurry seal 3-8 5) Chip seal 3-6 6) Microsurfacing 3-8 7) Micro mill (25mm) 1-4 8) Cold-in-place recycling and

overlay 10-15

10) Hot-in-place recycling 5-7 11) Thin hot mix overlay

(

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Cost Estimation

Empirical design - Example

Option 1 Option 2

6 cm Asphalt Surface Course

25 cm Asphalt Base Course

35 cm Aggregate Base Layer

Subgrade Layer



17 cm Cement Stabilized Base Layer

Subgrade Layer

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ME Design Example Step 1

We have to start with a section



35 cm Aggregate Base Layer

Subgrade Layer


Traffic = 41 Million ESAL

WMAPT = 43.5 C

Estimate Material properties: Testing/Correlations

Asphalt layer: two mixtures Surface and base

Aggregate Base: CBR 65%, Mr = 255 Mpa

Subgrade Layer: CBR 10%, Mr = 100 Mpa

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Surface Course

Pen 40/50 T1 = 15.6 C Pen= 17

T2 = 14 C Pen = 43

A = 0.033

PI = 1.326

T800pen = 63.5 C

WMAPT = 43.5 C

Binder S = 5 Mpa

Binder by wt = 3.9%

Binder by Volume = 8%

Air voids % = 6%

Aggregate Volume = 86 %

Mix Modulus = 3000 Mpa

Base Course

Pen 60/70 T1 = 15.6 C Pen= 25

T2 = 14 C Pen = 64

A = 0.043

PI = -0.5101

T800pen = 50.38 C

WMAPT = 43.5 C

Binder S = 1 Mpa

Binder by wt = 3.5%

Binder by Volume = 7%

Air voids % = 6%

Aggregate Volume = 87 %

Mix Modulus = 1800 Mpa


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Linear Elastic Analysis Any Program

(recommend Circly associated with Austroads)

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Smix Vb Strain N

AC Surface

Layer3000 8 4.74E-05 1,712,553,784

AC Base Layer 1800 7 8.92E-05 102,951,808

Subgrade 5.48E-04 404,913,284

Design Traffic (Million)

Empirical (power 4) = 41

ME- Fatigue (power 5) = 59

ME- Rutting (Power 7) = 161

Over Design

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Thanks!

Discussions

4.5 Empirical Pavement Design Example This section provides an example for an empirical flexible pavement design using the 1993 American Association of State Highway and Transportation Officials (AASHTO) Guide for Design of Pavement Structures.

The example is a 4 lane highway that will link Adu Dhabi Island to Al Ain. The soil is mainly characterized as A-3 Silty-Sand soil with a CBR of 10%. The traffic study shows that the current one way Average Annual Daily Traffic (AADT) is about 1700 vehicle with 60% Buses and trucks (Classes 4 to 13). Flexible pavement is recommended for this road. However, two scenarios will be used to compare the most economical option of the two. The first option is to use typical multi layer structure with aggregate granular base layer. While, the second option is to use a deep strength structure, which includes a cement stabilized base layer.

The following are the required inputs for the pavement design.

4.5.1 Environment The ground water table (GWT) along the roadway is deep and will not impact the moisture content of the subgrade layer. Accordingly, no correction is need for the subgrade modulus.

4.5.2 Traffic Traffic is very important and requires accurate data. A traffic survey was conducted in a nearby existing road. Both vehicle count and vehicle classification was conducted in the survey in addition to an axle load survey. The following parameters are taken for the pavement design:

Vehicle Classifications: From the traffic survey it was found that the traffic is divided into different vehicle classes as given Table 4-14. The AADT per vehicle class is shown in the third column. The truck traffic from this would be the summation of the vehicle counts from class 4 to class 13. This would yield an Annual Average Daily Truck Traffic (AADTT) of 1700*0.6= 1020 vehicle per day.

Axle load distribution: the Axle load survey gave the percentage of axle load distributions for each of the single, tandem and Tridem axles, as shown in Table 4-15, Table 4-16, and Table 4-17, respectively. These loads were used to calculate the EALF as given in Equation 2-10. The standard axle load from Table 2-3 for the single, tandem and Tridem axles were 80, 135 and 181 kN, respectively. Also, the power used in the calculation is 4 for the empirical design method as given in Table 2-4. The EALF for each load group is given in the third column.

The EALF is then multiplied by the percentage of this axle load to obtain the individual truck factor (TF) as shown in the fourth column. The individual values are then summed up to obtain the total TF for each axle.

The total TF for all axles types summation of the three values i.e. 0.3069+0.7984+1.2914 = 2.3967.

Table 4-14: Vehicle Classification Distribution

Vehicle Class Percentage of Total Traffic AADT

1 0 0

2 10 170

3 30 510

4 1 17

5 30 510

6 6 102

7 2 34

8 5.5 93.5

9 13 221

10 2.08 35.36

11 0.3 5.1

12 0.06 1.02

13 0.06 1.02

Total 100 1700

Design life: 20 years The growth rate was taken to be 6.5%. Using a linear growth factor (GF) as given in

Equation 2-7 will give a GF of 2.3. The lane factor (LDF) and direction factor (DF) were both taken as 100% i.e. 1. The previous parameters are used to calculate the total equivalent single axle load (ESAL) as given in Equation 2-11. ESAL = 1700*0.6*2.3967*2.3*1*1*20*365 = 41,046,106.

Table 4-15: Single Axle Load Distribution

Axle Load (KN) Percentage Equivalent Axle Load

Factor (EALF) Single TF

13.34 5.26 0.0 0.0000

17.79 3.235 0.0 0.0001

22.24 5.211 0.0 0.0003

26.69 5.151 0.0 0.0006

31.14 6.235 0.0 0.0014

35.59 8.435 0.0 0.0033

40.03 9.899 0.1 0.0062

44.48 11.163 0.1 0.0107

48.93 10.061 0.1 0.0141

53.38 8.144 0.2 0.0161

57.83 6.266 0.3 0.0171

62.28 4.755 0.4 0.0175

66.72 3.667 0.5 0.0177

71.17 2.967 0.6 0.0186

75.62 2.267 0.8 0.0181

80.07 1.818 1.0 0.0182

84.52 1.364 1.2 0.0170

88.96 1.031 1.5 0.0158

93.41 0.791 1.9 0.0147

97.86 0.541 2.2 0.0121

102.31 0.417 2.7 0.0112

106.76 0.29 3.2 0.0092

111.21 0.206 3.7 0.0077

115.65 0.243 4.4 0.0106

120.10 0.144 5.1 0.0073

124.55 0.084 5.9 0.0049

129.00 0.079 6.8 0.0053

133.45 0.04 7.7 0.0031

137.89 0.1 8.8 0.0088

142.34 0.042 10.0 0.0042

146.79 0.024 11.3 0.0027

151.24 0.017 12.8 0.0022

155.69 0.011 14.3 0.0016

160.14 0.01 16.1 0.0016

164.58 0.008 17.9 0.0014

169.03 0.008 19.9 0.0016

173.48 0.007 22.1 0.0015

177.93 0.009 24.5 0.0022

Total 100 0.3069

Table 4-16: Tandem Axle Load Distribution

Axle Load (KN) Percentage Equivalent Axle Load

Factor (EALF) Tandem TF

26.69 7.572 0.0 0.0001

35.59 7.496 0.0 0.0004

44.48 6.8 0.0 0.0008

53.38 6.618 0.0 0.0016

62.28 7.128 0.0 0.0032

71.17 6.75 0.1 0.0052

80.07 6.608 0.1 0.0082

88.96 6.499 0.2 0.0123

97.86 6.441 0.3 0.0178

106.76 5.657 0.4 0.0221

115.65 5.021 0.5 0.0270

124.55 4.818 0.7 0.0349

133.45 4.556 1.0 0.0435

142.34 3.799 1.2 0.0470

151.24 3.206 1.6 0.0505

160.14 2.496 2.0 0.0494

169.03 2.039 2.5 0.0501

177.93 1.509 3.0 0.0455

186.83 1.054 3.7 0.0387

195.72 0.826 4.4 0.0365

204.62 0.77 5.3 0.0406

213.51 0.543 6.3 0.0340

222.41 0.395 7.4 0.0291

231.31 0.309 8.6 0.0266

240.20 0.277 10.0 0.0278

249.10 0.212 11.6 0.0246

258.00 0.127 13.3 0.0169

266.89 0.12 15.3 0.0183

275.79 0.108 17.4 0.0188

284.69 0.058 19.8 0.0115

293.58 0.044 22.4 0.0098

302.48 0.039 25.2 0.0098

311.38 0.038 28.3 0.0108

320.27 0.027 31.7 0.0086

329.17 0.012 35.3 0.0042

338.06 0.012 39.3 0.0047

346.96 0.006 43.6 0.0026

355.86 0.01 48.3 0.0048

Total 100 0.7984

Table 4-17: Tridem Axle Load Distribution

Axle Load

(KN) Percentage

Equivalent Axle

Load Factor

(EALF) Tridem

TF

53.38 29.409 0.0 0.0022

66.72 6.9 0.0 0.0013

80.07 5.725 0.0 0.0022

93.41 5.212 0.1 0.0037

106.76 3.423 0.1 0.0041

120.10 3.376 0.2 0.0065

133.45 4.24 0.3 0.0125

146.79 3.318 0.4 0.0144

160.14 5.169 0.6 0.0317

173.48 3.728 0.8 0.0315

186.83 6.634 1.1 0.0753

200.17 4.2 1.5 0.0628

213.51 3.268 1.9 0.0633

226.86 3.073 2.5 0.0758

240.20 2.864 3.1 0.0888

253.55 1.955 3.9 0.0753

266.89 1.252 4.7 0.0592

280.24 1.071 5.7 0.0615

293.58 1.12 6.9 0.0775

306.93 1.312 8.3 0.1085

320.27 0.812 9.8 0.0796

333.62 0.32 11.5 0.0369

346.96 0.318 13.5 0.0429

360.31 0.41 15.7 0.0644

373.65 0.461 18.2 0.0837

387.00 0.097 20.9 0.0203

400.34 0.056 23.9 0.0134

413.68 0.083 27.3 0.0226

427.03 0.017 31.0 0.0053

440.37 0.132 35.0 0.0463

453.72 0.045 39.5 0.0178

Total 100 1.2914

4.5.3 Materials Flexible pavement structure can be composed of several layers such as the subgrade, granular base/subbase, cement stabilized base and asphalt concrete layer. In the following section the modulus of each possible layer will be estimated using the models given in Chapter 3 of this manual.

4.5.3.1 Subgrade Layer The subgrade layer resilient modulus (Mr) is calculated from CBR test results. As given in the heading of the example, the subgrade soil in the road area is predominately A-3 Silty-

Sand soil with a minimum CBR of 10%. Equation 3-1 is used to estimate the Mr of the subgrade layer. The subgrade Mr is an essential input into the 1993 AASHTO design equation.

Mr = 1500*10= 15,000 psi. = 100 MPa

4.5.3.2 Aggregate Base Layer According to Abu Dhabi Roads Material Specifications, the aggregate base layer material should satisfy a minimum CBR of 65%. If this value is assumed to be achieved in the site during construction, then the Mr for the base layer would be calculated from Equation 3-2.

Mr = 2555*65^0.64 = 36,953 psi = 255 MPa.

Figure 3-1 is then used to estimate the layer coefficient for the granular base layer (a2) which is yield to be 0.13 per inch = 0.05 per cm.

4.5.3.3 Cement Stabilized base layer The cement stabilized base (CTB) layer is used as a deep strength layer in such cases that heavy traffic is expected to use the pavement structure. The cement stabilized layer will increase the load carrying capacity of the pavement structure without the need to increase the total thickness of the pavement structure. Figure 3-3 can be used to obtain the layer coefficient based on unconfined compressive strength after 7 days of the CTB material. Test results from project using CTB provided a unconfined compressive strength of 900 psi or a modulus of 850,000 psi (5,860 MPa). This

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