Pavement Design good ref.

PAVEMENT DESIGN MANUAL

Commentary Report

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

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.

Contents Approval and Amendment Record This report has been issued and amended as follows:

Issue

Revision

1.0

0

Description

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

Page i

Lead Author

Mohamed Elbasyouny (PIL)

Lead Reviewer

Date

Mohamed Elbasyouny (PIL)

6/05/2013

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

5

6

7

4.1

1993 AASHTO Empirical method ...................................................................................... 5

4.2

Austroads Mechanistic-empirical method .......................................................................... 5

4.3

Abu Dhabi Municipality Pavement Design Manual ............................................................ 7

scope of manual .................................................................................................................... 8 5.1

Application of this manual ................................................................................................. 8

5.2

Content and format ........................................................................................................... 8

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

Acknowlegment ................................................................................................................... 13

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

Page ii

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

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

Page iii

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 DoT’s 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. Page 1

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 manual’s approach is consistent with DoT’s 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.

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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. 2. 3. 4. 5. 6. 7. 8. 9.

Get comprehensive brief from DoT Staff to understand their requirements. Submit Preliminary report to confirm DoT’s 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 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.

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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.

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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

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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 pavement’s tolerance level, based on material characteristics.

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Traffic

Foundation

Project Reliability

Performance Criteria

Climate

Inputs

Material Properties

Trial Section

Analysis

Pavement Analysis

Accept

No

Yes Comparison of Designs

Selection

Viable Design

Select Design

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.

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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 road’s 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 DoT’s 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 DoT’s 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. Page 8

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.

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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 Limited’s completion of the Pavement design manual is shown on the schedule included in PIL’s 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: First workshop Completion of Stakeholder Review: Delivery of First Draft Document: Completion of DOT Reviews Submission of Draft Document: Second Workshop: Final Comments: Final Draft Document: Final Document:

10 March 2011 14 March 2011 31 March 2011 April 2012 July 2012 September 2012 12 November 2012 01 December 2012 February 2013 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. Page 10

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.

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The following table list the technical meeting held during the development of the PDM. Table 1 Technical Meetings Information Date

Title

Agenda

PDM Preliminary Discussion of the Preliminary 20-Feb-11 report report and manual outline

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

Parviz Djahani (DoT), Dr. Salim Discussion of the Preliminary PDM Preliminary Suliman (DOT), Willie Victor 10-March-11 report and preparation for the report (Aurecon), Dr. Rasin Mufti (PIL), first workshop Mohamed Elbasyouny (PIL) Updated outline, schedule PDM Workshop and the comments received 05-April-11 comments on the PDM during the workshop 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) Dr. Salim Suliman (DOT), Dr. Rasin Mufti (PIL), Mohamed Elbasyouny (PIL)

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

Rob Hranac (TrafQuest), Mohamed El-Basyouny (PIL), Ahmed Abdel Dayem, (Trafquest)

15PDM progress Septembermeeting 11

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

Progress in PDM

06-June-12

PDM Review

Dr. Salim Suliman (DOT), Dr. Nabil Salman (DoT), Dr. Rasin Comments of PDM First Draft Mufti (PIL), Mohamed Elbasyouny (PIL)

12-June-12

PDM Review

Comments of PDM First Draft

Dr. Salim Suliman (DOT), Mohamed Elbasyouny (PIL)

Parviz Djahani (DoT), Dr. Salim Suliman (DOT), Jihad Sawan 19Meeting on Discuss location and content (DoT), Abdulla Al Shaibani DecemberPavement of Pavement Condition (DoT), Willie Victor (Aurecon), 12 Condition Survey Survey Andrew Harley (Halcrow), Mohamed Elbasyouny (PIL)

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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

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

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UNIFYING AND STANDARDIZING OF ROAD ENGINEERING PRACTICES CONSOLIDATED REVIEWER’S COMMENT SHEET

A14

Document Title:

ACONEX Document No. of Interim Deliverable Reviewed: Package Name: Sub-Package Name:

Pavement Design Manual MAN-000540

Deliverable Ref:

A14.12

3

Dated:

Revision No:

Consolidated Comments Submitted to DDC:

Geometry Geometry 2

Title of Interim Deliverable:

Second Draft Document

#################### ACONEX Document No. of Approved Content Outline:

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

Priorities: High Priority (H):

Comments that will cause the document to be unacceptable. Medium Priority (M): Comments which require the document to be revised and resubmitted. Low Priority (L): Observations such as typographical errors which may be corrected during next revision.

No

Subject

Page / Section No

Priority (H,M,L) M

Reviewer’s Comment Bus stop pavement area should be laid with bitumen modified red colored asphalt wearing course.

Reviewer

Reviewer's Organization DOT-Public Transport Division

DDC Response

1

Bus stops

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


Corrected

4

Par 2.1 Overview

Page 9

First paragraph. Careful study and characterization of these factors is … Change "is" to "are"

L

Johan Calitz


Corrected

5

Par 2.2 Environment

Page 9

Environment includes a many variables…. Omit "a".

L

Johan Calitz


Corrected

6

Figure 2-2

Page 12

Cannot read some rainfall figures

H

Johan Calitz


Corrected

7

Table 2-1

Page 12

Start table on next page to fit the whole table on 1 page

M

Johan Calitz


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


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

M

Johan Calitz


Corrected

10

Paragraph 2.3.11

Page 22

Last sentence of first paragraph: "As an alternative method, can apply L .." Add "designers" before "can apply"

Johan Calitz


Corrected

11

Chapter 3 Pavement Materials

Page 25

Second paragraph. Add "a" to "Pavement is composed of .."

Johan Calitz


Corrected

L

Page 1 of 10

Added to Roads Specification manual


A14

Document Title:



Deliverable Ref:

A14.12

3

Dated:

Revision No:


Geometry Geometry 2







Reviewer's Organization Aurecon Docment Reviewer

DDC Response

Johan Calitz


Corrected

The title of this figure is on the page following the figure and should be L moved to the bottom of the figure on page 29

Johan Calitz


Corrected

page 30

Add "In the AASHTO Road Test the basis of these correlations is" to M 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

Johan Calitz


Corrected

Figure 3-2

Page 31

This figure copied from the AASHTO manual page II-21 should be M revised so that the footers which include AASHTO manual references are not shown.

Johan Calitz


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.

M

Johan Calitz


Corrected

18

Par 3.3 modified granular materials

Page 33

Last sentence of first paragraph : Change "stabilised" to "modified" in M the sentence "Austroads specifies that stabilised granular materials …". Refer page 53 Autroads Manual

Johan Calitz


Corrected

19

Figure 3-3

Page 35


Johan Calitz


Corrected

No

Subject

Page / Section No

12

Par 3.2.1 Empirical design for granular base and subbase materials

Page 28

13

Figure 3-1

Page 29

14

Figure 3-1

15

Priority (H,M,L)

Reviewer’s Comment

Reviewer

Add "The AASHTO Road Test basis of these correlations is" to the M 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 This figure copied from the AASHTO manual page II-19 should be M revised so that the footers which include AASHTO manual references are not shown.

Johan Calitz

page 29

Par 3.2.1 Empirical design for granular base and subbase materials

16

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Johan Calitz


Corrected

Page 42

Change "asphalt" in title to "asphalt concrete". Refer Austroads figure M 6.10 page 71

Johan Calitz


Corrected

Figure 4-3

Page 55

Change "Foundatio" to "Foundation" and "Climat" to "Climate". Refer Austroads page 97.

M

Johan Calitz


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


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


Corrected

27

Par 4.3.3.2Determine required structural design

Page 67

First paragraph. "Refer to section X.". Provide correct reference

H

Johan Calitz


Corrected

28

Par 4.3.3.2Determine required structural design

Page 67 - 69

Please provide reference to the design figures: Figure 4-6, Figure 47, Figure 4-8 and Figure 4-9. Could not be found in AASHTO or Austroads Design manuals

M

Johan Calitz


Corrected

No

Subject

Page / Section No

Priority (H,M,L)


Reviewer

20

Figure 3-4

Page 36


Johan Calitz

21

Par 3.5.1 Empirical design for asphalt concrete materials

Page 38

Change the second paragraph to the following: "The structural M 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

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.

23

Figure 3-7

24

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Johan Calitz


Corrected

Page 74

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

Johan Calitz


Corrected

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

M

Johan Calitz


Corrected

34

Equation 4-12

Page 75

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

Johan Calitz


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

M

Johan Calitz


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.

L

Johan Calitz


Added

37

Par 4.4.4.1 Design factors

Page 79

Change "The Four .." to "The four …" in the first paragraph

L

Johan Calitz


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 .."

M

Johan Calitz


Corrected

No

Subject

Page / Section No

Priority (H,M,L)


Reviewer

29

Par 4.3.4 Joint details

Page 70

Change "joint" to "joints" in first paragraph

L

Johan Calitz

30

Par4.3.5.1Rigid pavement types

Page 72

Third sentence of first paragraph. Change "LPCP" to "JPCP"

L

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%.

32

Equation 4-11

33

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Corrected

H

Johan Calitz


Corrected

page 156

In the third paragraph mention is made of adding "bitumen". This is the M Australian and American thermodology which is used worlwide. In this manual "bitumen" is called "asphalt".

Johan Calitz


Corrected

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.

H

Johan Calitz


Corrected

45

Appendix A: Developing Effective Modulus of Subgrade Reaction

page 185

The first paragraph says "This appendix provides an excerp from the M 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

Johan Calitz


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

M

Johan Calitz


Added

47

Glossary

Glossary to be added

M

Johan Calitz


Added

No

Subject

Page / Section No

Priority (H,M,L)


Reviewer

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

H

Johan Calitz

40

Par 8.4 Pavement preservation treatments

Page 144

Recommend that paragraph 8.5 Preservation Treatments be placed M 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.

41

Table 8-2: Pavement treatments and Page 147 and page Table 8-3 Pavement treatment cost 148 and expected life

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.

42

Profile milling, cold in place recycling, page 155 to page 157 These paragraphs should be numbered 8.5.2.6 ; 8.5.2.7; 8.5.2.8; Hot-in -place asphalt recycling, Full8.5.2.9 respectively depth asphalt repair (patching)

43

Hot -in-place asphalt recycling

44

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Traffic Projections

Page / Section No

/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.

Priority (H,M,L)

L

Reviewer

Al Ain Municipality

Reviewer's Organization

DDC Response This is included in the traffic manual

Al Ain Municipality

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

2

3

Equivlent Axle load factor

Modified granular material

/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

/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.

/3.4.2

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

L

Al Ain Municipality

M

Al Ain Municipality

Al Ain Municipality

added

Al Ain Municipality There are many relationships and none is recommended

4

Stabilized material

M

Page 6 of 10

Al Ain Municipality

Al Ain Municipality


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Recycled Material

Page / Section No

Priority (H,M,L)


/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.

/3.9.4

Include Methodology for Cold In situ Recycling with form bitumen, foamed asphalt mixes.

Reviewer

M

Al Ain Municipality

M

Al Ain Municipality


DDC Response Added but more information is included in the specification manual

Al Ain Municipality

Added in the maintenance chapter 6

7

Recycled Material

Interlocking Pavers Design

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

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

M

Al Ain Municipality

Al Ain Municipality

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

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 43 does not provide layer coefficient for concrete paver as well.

H

Page 7 of 10

Al Ain Municipality

Al Ain Municipality


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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, Subbase with CBR 30% used in Dubai. Therefore please provide reference to the above requirement to justify.

Priority (H,M,L)

Reviewer


L

Al Ain Municipality

M

Al Ain Municipality

Al Ain Municipality

L

Al Ain Municipality

Al Ain Municipality

DDC Response added

Al Ain Municipality

Modified as possible 10

Pavement treatment cost and expected life

The Manual should use the cost inputs based on the local condition rather than referring to US condition.

11

Pavement treatment cost and expected life

The envinmental impact should be considered for the cases, Alternatives 1 &2

The proposed method does not include the envirnmental effect.

The manual covers Austrailian as well as American standards

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

M

Page 8 of 10

Al Ain Municipality

Al Ain Municipality


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Pavement Design Check list

General Comment

Emperical Pavement Design Example

/4.5

14

1 Pavement Design Manual












Priority (H,M,L)


Reviewer


Provide check list sheet that include requirements information for the pavement design to assess designer in revising pavement design documents

L

Al Ain Municipality

Al Ain Municipality

Provide detailed example for pavement design using ME method

M

Al Ain Municipality

Al Ain Municipality

Traffic requires more details on Traffic count and axle configurations

Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel

Add Examples Techniques for Stabilization and Material selection More details on Pavement Management Systems Maintenance chapter need to include diagnostic and methods Graphics throughout the manual need to be improved and made clearer. 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 Add section on Paver interlocking blocks design – use UK Add sketches for axle types Adjust design lane, % of trucks and other traffic factors. Check equation 2.9 and add example

Page 9 of 10

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

Provided and added to chapter 4.

addressed in the final version

DOT added

DOT added

DOT This would be covered in the management manual

DOT added chapter on pavement evaluation

DOT All graphs are fixed

DOT DOT DOT

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

DOT Added

DOT Corrected

DOT Corrected

DOT


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

Reviewer

Emphasize that better quality material should be at the top for empirical design. Add more details on the Geo-grids functionality and description Comment on reliability and its impact on structure design Adjust the drainage coefficient to include 1.2 for drainage layers.

Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel Dr.Salim/ Dr. Nabel

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

Dr.Salim/ Dr. Nabel

Include CBR power model


DDC Response Corrected

DOT Added

DOT text is added

DOT DOT

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

DOT Corrected

DOT Corrected


Page 10 of 10

DOT

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.

Page 26

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UNIFYING AND STANDARDIZATION OF HIGHWAY ENGINEERING PRACTICES


Workshop 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

1

5/6/2013

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 Parson’s 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.

2

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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

3

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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

4

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Chapter 2 Pavement Components

Rainfall 56.3 mm


Weighted mean annual air temperature 45.0° C to 38.7° C, 43.5° C

5

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Chapter 2 Pavement Components 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 Single axle, single tire Single axle, dual tire Tandem axle, single tire Tandem axle, dual tire Tridem axle, dual tire Quad axle, dual tire

Load (kN) 53 80 90 135 181 221

Design Method Empirical Mechanistic – Control Fatigue Mechanistic – Control Rutting

Load Damage Exponent (m) 4 5 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

Chapter 3 Pavement Materials Subgrade Soils Mr = 10 * CBR CBR < 20% (Empirical) 0.64 Mr = 2555 * CBR CBR > 20% (Empirical) Log CBR = 2.494 - 1.131 log (DCP) (ME) Back calculations Using Falling Weight Deflectometer testing (ME)

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Chapter 3 Pavement Materials Aggregate Base Material a2 = 0.249(log10EBS) - 0.977 (per inch) a3 = 0.227(log10ESB) - 0.839 (per inch) Mr Testing Default Values

(Empirical) (Empirical) (ME) (ME)

Chapter 3 Pavement Materials Cement Stabilized Material a2 = 0.25 (Empirical) 28 days Unconfined Testing (ME) Default Values (ME)

Property

Lean Mix Concrete

Base 4-5% cement

Range of Modulus (MPa) Typical Modulus (MPa) Degree of anisotropy Range of Poisson’s ratio Typical value of Poisson’s ratio

5000-15000 7000 1 0.1-0.3 0.2

3000-8000 5000 1 0.1-0.3 0.2

Subbase quality crushed rock 2-4% cement 2000-5000 3500 1 0.1-0.3 0.2

Subbase quality crushed rock 4-5% cement 1500-3000 2000 1 0.1-0.3 0.2

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Chapter 3 Pavement Materials 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

Chapter 4 New Design

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Chapter 4 New Design - ME Traffic

Foundation

Project Reliability

Performance Criteria

Climate

Material Properties

Trial Section

Inputs

Analysis

Pavement Analysis

Accept

No

Yes Comparison of Designs

Selection

Viable Design

Select Design

Chapter 4 New Design - ME

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Chapter 4 New Design 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 For Example Cause of Rutting Total pavement thickness inadequate Unstable granular layer due to saturation Unstable layer due to low shear strength Unstable AC mix (including stripping) Compaction by Traffic Studded tire wear

Layer(s) Causing Rut Subgrade Base or subbase Base Surface Surface, base, subbase Surface

Solution Thick overlay Remove unstable layer over thick overlay Remove unstable layer or thick overlay Remove unstable layer Surface milling and/or levelling overlay Surface milling and/or levelling overlay

Chapter 5 Rehabilitation Repairs needed before overlay Distress Type Alligator cracking

Linear cracks

Rutting Surface irregularities

Required Repair • Repair all high-severity alligator cracking. • Repair medium-severity cracking, unless using reflective crack control or paving fabric. • Remove soft subsurface material. • 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. • Apply milling or place a levelling course to remove ruts. • Investigate which layer caused any severe rutting. • Investigate depressions, humps, ad corrugations; apply treatment as necessary, which typically involves removal and replacement.

13

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Chapter 5 Rehabilitation Structural Evaluation Visual Survey and material testing Nondestructive Testing (NDT) Estimation of Remaining surface life

Chapter 5 Rehabilitation 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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Chapter 8 Pavement Maintenance Distress identification – FHWA Distress Manual 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.1.6 3.1.7 3.1.8

Fatigue (alligator) cracking Bleeding Block cracking Corrugation and shoving Depression Joint reflection cracking Longitudinal cracking Patching

3.1.9 3.1.10 3.1.11 3.1.12 3.1.13 3.1.14 3.1.15 3.1.16 3.1.17

Polished aggregate Potholes Ravelling Rutting Slippage cracking Stripping Transverse (thermal) cracking Water bleeding and pumping Edge Cracking

Chapter 8 Pavement Maintenance Treatment options and cost Pavement 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-m ill 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

Chapter 9 Life Cycle Cost Analysis Maintenance and Rehabilitation Frequencies

1) 2) 3) 4) 5) 6)

Treat ment 50 mm overlay 50 mm mill and overlay Scrub seal Slurry seal Chip seal Microsurf acing

7) Micro mill (25mm) 8) Cold-in-place recycling and overlay 10) Hot-in-place recycling 11) Thin hot mix overlay (<50mm) 12) Patching 13) Thick overlay (125mm) 14) Full depth reclamation and 100 mm overlay 15) Complete reconstruction

Expected Life (Years) 7-10 10-15 2-5 3-8 3-6 3-8 1-4 10-15 5-7 5-8 3-5 8-15 20+ 20+

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Chapter 9 Life Cycle Cost Analysis Cost Estimation

Empirical design - Example Option 1

Option 2

6 cm Asphalt Surface Course

6 cm Asphalt Surface Course

25 cm Asphalt Base Course

25 cm Asphalt Base Course

17 cm Cement Stabilized Base Layer 35 cm Aggregate Base Layer Subgrade Layer Subgrade Layer

18

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ME Design Example – Step 1 We have to start with a section 6 cm Asphalt Surface Course 25 cm Asphalt Base Course

35 cm Aggregate Base Layer

Subgrade Layer

ME Design Example – Step 2 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

19

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ME Design Example – Step 2 Surface Course

Base Course

Pen 40/50

Pen 60/70

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

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

ME Design Example – Step 2

20

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ME Design Example – Step 3 Linear Elastic Analysis – Any Program (recommend Circly associated with Austroads)

21

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ME Design Example – Step 4

ME Design Example – Step 4 Smix

Vb

Strain

N

AC Surface Layer

3000

8

4.74E-05

1,712,553,784

AC Base Layer

1800

7

8.92E-05

102,951,808

5.48E-04

404,913,284

Subgrade

Design Traffic (Million) Empirical (power 4) = 41 ME- Fatigue (power 5) = 59 ME- Rutting (Power 7) = 161

Over Design

22

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Thanks!

Discussions

23

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 0.3069+0.7984+1.2914 = 2.3967.

summation

of

the

three

values

i.e.

Table 4-14: Vehicle Classification Distribution Vehicle Class 1 2 3 4 5 6 7 8 9 10 11 12 13 Total

• • •

Percentage of Total Traffic 0 10 30 1 30 6 2 5.5 13 2.08 0.3 0.06 0.06 100

AADT 0 170 510 17 510 102 34 93.5 221 35.36 5.1 1.02 1.02 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

13.34 17.79 22.24 26.69 31.14 35.59 40.03 44.48 48.93 53.38 57.83 62.28 66.72 71.17 75.62 80.07 84.52 88.96 93.41 97.86 102.31 106.76 111.21 115.65 120.10 124.55 129.00 133.45 137.89 142.34 146.79 151.24 155.69 160.14 164.58 169.03 173.48 177.93 Total

5.26 3.235 5.211 5.151 6.235 8.435 9.899 11.163 10.061 8.144 6.266 4.755 3.667 2.967 2.267 1.818 1.364 1.031 0.791 0.541 0.417 0.29 0.206 0.243 0.144 0.084 0.079 0.04 0.1 0.042 0.024 0.017 0.011 0.01 0.008 0.008 0.007 0.009 100

Equivalent Axle Load Factor (EALF) Single 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.1 0.2 0.3 0.4 0.5 0.6 0.8 1.0 1.2 1.5 1.9 2.2 2.7 3.2 3.7 4.4 5.1 5.9 6.8 7.7 8.8 10.0 11.3 12.8 14.3 16.1 17.9 19.9 22.1 24.5

Table 4-16: Tandem Axle Load Distribution

TF 0.0000 0.0001 0.0003 0.0006 0.0014 0.0033 0.0062 0.0107 0.0141 0.0161 0.0171 0.0175 0.0177 0.0186 0.0181 0.0182 0.0170 0.0158 0.0147 0.0121 0.0112 0.0092 0.0077 0.0106 0.0073 0.0049 0.0053 0.0031 0.0088 0.0042 0.0027 0.0022 0.0016 0.0016 0.0014 0.0016 0.0015 0.0022 0.3069

Axle Load (KN)

Percentage

26.69 35.59 44.48 53.38 62.28 71.17 80.07 88.96 97.86 106.76 115.65 124.55 133.45 142.34 151.24 160.14 169.03 177.93 186.83 195.72 204.62 213.51 222.41 231.31 240.20 249.10 258.00 266.89 275.79 284.69 293.58 302.48 311.38 320.27 329.17 338.06 346.96 355.86 Total

7.572 7.496 6.8 6.618 7.128 6.75 6.608 6.499 6.441 5.657 5.021 4.818 4.556 3.799 3.206 2.496 2.039 1.509 1.054 0.826 0.77 0.543 0.395 0.309 0.277 0.212 0.127 0.12 0.108 0.058 0.044 0.039 0.038 0.027 0.012 0.012 0.006 0.01 100

Equivalent Axle Load Factor (EALF) Tandem 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.2 0.3 0.4 0.5 0.7 1.0 1.2 1.6 2.0 2.5 3.0 3.7 4.4 5.3 6.3 7.4 8.6 10.0 11.6 13.3 15.3 17.4 19.8 22.4 25.2 28.3 31.7 35.3 39.3 43.6 48.3

Table 4-17: Tridem Axle Load Distribution

TF 0.0001 0.0004 0.0008 0.0016 0.0032 0.0052 0.0082 0.0123 0.0178 0.0221 0.0270 0.0349 0.0435 0.0470 0.0505 0.0494 0.0501 0.0455 0.0387 0.0365 0.0406 0.0340 0.0291 0.0266 0.0278 0.0246 0.0169 0.0183 0.0188 0.0115 0.0098 0.0098 0.0108 0.0086 0.0042 0.0047 0.0026 0.0048 0.7984

4.5.3

Axle Load (KN)

Percentage

53.38 66.72 80.07 93.41 106.76 120.10 133.45 146.79 160.14 173.48 186.83 200.17 213.51 226.86 240.20 253.55 266.89 280.24 293.58 306.93 320.27 333.62 346.96 360.31 373.65 387.00 400.34 413.68 427.03 440.37 453.72 Total

29.409 6.9 5.725 5.212 3.423 3.376 4.24 3.318 5.169 3.728 6.634 4.2 3.268 3.073 2.864 1.955 1.252 1.071 1.12 1.312 0.812 0.32 0.318 0.41 0.461 0.097 0.056 0.083 0.017 0.132 0.045 100

Equivalent Axle Load Factor (EALF) Tridem 0.0 0.0 0.0 0.1 0.1 0.2 0.3 0.4 0.6 0.8 1.1 1.5 1.9 2.5 3.1 3.9 4.7 5.7 6.9 8.3 9.8 11.5 13.5 15.7 18.2 20.9 23.9 27.3 31.0 35.0 39.5

TF 0.0022 0.0013 0.0022 0.0037 0.0041 0.0065 0.0125 0.0144 0.0317 0.0315 0.0753 0.0628 0.0633 0.0758 0.0888 0.0753 0.0592 0.0615 0.0775 0.1085 0.0796 0.0369 0.0429 0.0644 0.0837 0.0203 0.0134 0.0226 0.0053 0.0463 0.0178 1.2914

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 value will yield a layer coefficient of 0.24 per inch (0.10 per cm).

4.5.3.4

Asphalt Concrete Layer

The aggregate gradation and binder content in Abu Dhabi mix design specification differ for different asphalt concrete (AC) layer types mainly, surface course and base course. This difference in gradation and binder content will provide a different modulus for each layer. However, in the empirical design the same modulus is assumed for all AC layers. In the empirical pavement design the AC materials is assumed to have a resilient modulus of 3.1 GPa (450,000 psi) which will yield a layer coefficient value of 0.44 per inch and 0.17 per cm. In some cases when an open graded friction course or an existing asphalt layer is used in the pavement structure the modulus value can be reduced to 300,000 psi which reduces the layer coefficient to 0.35 per inch as given in Figure 3-5. For this example, the common a1 value of 0.44 will be used.

4.5.4

Structure design

The traffic and material are the main inputs for the pavement structure design. However, additional inputs are required according to the 1993 AASHTO guide procedure. The additional inputs are as follows for Rural Roads: • • • • •

Reliability level (%) = 99.9 % as given in Table 4-1 for Rural Roads. Standard normal deviate = -3.09052 for the 99.9 % reliability Initial serviceability = 4.2 Terminal Serviceability = 3.0 Overall standard deviation = 0.45

In addition to: • • • • • • •

ESAL = 41,046,106 Subgrade Mr = 15,000 psi Base Mr = 36,953 psi CTB Mr = 850,000 psi Layer coefficient for AC a1 = 0.17 Layer coefficient for aggregate base a2 = 0.05 Layer coefficient for CTB base a2 = 0.10

Equation 4-1 is then used to calculate the required structure number (SN) at the top of the subgrade (SN2) and base layer (SN1). The required SN2 is equal to 6.93. While, SN1 is equal to 5.18. SN1 is obtained by using the MR of the base layer as the input to the 1993 AASHTO equation. Option 1 using aggregate granular base: The total thickness of the AC layer = SN1 / a1 = 5.18/0.17 = 30.5 cm i.e. 31 cm. This can be divided into 6 cm surface course and 25 cm base course. The thickness of the base layer = (SN2 – SN1)/a2 = (6.93 – (31*0.17))/0.05 = 33.2 cm i.e. 35 cm. This can be divided into 15 cm granular base layer and 20 cm granular subbase layer. Total SN = 31*0.17+35*0.05=7.02, which exceeds the 6.93 required from the 1993 AASHTO equation. Option 2 using cement stabilized base: In case of using the CTB, a new SN1 could have been obtained to reduce the AC thickness. However, in this example the AC thickness is kept the same at 31 cm, and makes the modification in the base layer thickness. The thickness of the base layer = (SN2 – SN1)/a2 = (6.93 – (31*0.17))/0.1 = 16.6 cm i.e. 17 cm of a CTB base layer. Total SN = 31*0.17+17*0.1=6.97, which exceeds the 6.93 required from the 1993 AASHTO equation.

4.5.5

Cost Analysis

There are two options for the pavement structure design for the given road, the first option has a total thickness of 66 cm and uses the aggregate as a base. While, the second option has a total thickness of 48 cm and uses the cement stabilized bases (CTB). These two options yield a cost difference in its construction as well as maintenance frequency over the life of the pavement. The initial construction cost will be considered here for this example, while for maintenance cost and users cost due to maintenance can be check in the example in Life cycle cost analysis Chapter 9 of this manual.

The AC cost will be the same since the AC thickness was kept constant. The cost of the 30 cm of the aggregate base costs 50 AED per unit area. The cost of the 17 cm of CTB is 40 AED per unit area. The total area of the project is 10 km with 4 lane road (10*1000*4*3.65 = 146,000 square meter). Accordingly, the expected cost saving in only the initial construction cost is 10*146,000, which is about 1.5 million AED.

Pavement Design good ref.

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