Pavement Rehabilitation and Asphalt Overlay Design Manual Appendices

210 Pages·2014·3.56 MB·English

Site Investigation Manual – 2013 Foreword

FOREWORD

The road network in Ethiopia provides the dominant mode of freight and passenger
transport and thus plays a vital role in the economy of the country. The network comprises
a huge national asset that requires adherence to appropriate standards for design,
construction and maintenance in order to provide a high level of service. As the length of
the road network is increasing, appropriate choice of methods to preserve this investment
becomes increasingly important.
In 2002, the Ethiopian Roads Authority (ERA) first brought out road design manuals to
provide a standardized approach for the design, construction and maintenance of roads in
the country. Due to technological development and change, these manuals require periodic
updating. This current version of the manual has particular reference to the prevailing
conditions in Ethiopia and reflects the experience gained through activities within the road
sector during the last 10 years. Completion of the review and updating of the manuals was
undertaken in close consultation with the federal and regional roads authorities and the
stakeholders in the road sector including the contracting and consulting industry.
Most importantly, in supporting the preparation of the documents, a series of thematic peer
review panels were established that comprised local experts from the public and private
sector who provided guidance and review for the project team.
This Manual supersedes the Site Investigation Manual part of the ERA Design Manuals of
2002. The procedures set out shall be adhered to unless otherwise directed by the
concerned bodies within ERA. However, I should emphasize that careful consideration to
sound engineering practice shall be observed in the use of the manual, and under no
circumstances shall the manual waive professional judgment in applied engineering. For
simplification in reference this manual may be cited as ERA’s Site Investigation Manual -
2013.
On behalf of the Ethiopian Roads Authority I would like to take this opportunity to thank
DFID, Crown Agents and the AFCAP team for their cooperation, contribution and support
in the development of the manual and supporting documents for Ethiopia. I would also like
to extend my gratitude and appreciation to all of the industry stakeholders and participants
who contributed their time, knowledge and effort during the development of the
documents. Special thanks are extended to the members of the various Peer Review Panels
whose active support and involvement guided the authors of the manual and the process.
It is my sincere hope that this manual will provide all users with both a standard reference
and a ready source of good practice for the design of roads, and will assist in a cost
effective operation, and environmentally sustainable development of our road network.
I look forward to the practices contained in this manual being quickly adopted into our
operations, thereby making a sustainable contribution to the improved infrastructure of our
country.
Comments and suggestions on all aspects from any concerned body, group or individual as
feedback during its implementation is expected and will be highly appreciated.

Addis Ababa, 2013

Zaid Wolde Gebriel
Director General, Ethiopian Roads Authority

Ethiopian Roads Authority Page i
Preface Site Investigation Manual – 2013

PREFACE

The Ethiopian Roads Authority is the custodian of the series of technical manuals, standard
specifications and bidding documents that are written for the practicing engineer in
Ethiopia. The series describe current and recommended practice and set out the national
standards for roads and bridges. They are based on national experience and international
practice and are approved by the Director General of the Ethiopian Roads Authority.

This Site Investigation Manual -2013 forms part of the Ethiopian Roads Authority series of
Road and Bridge Design documents. The complete series of documents, covering all roads
and bridges in Ethiopia, are contained within the series:

1. Geometric Design Manual
2. Site Investigation Manual
3. Geotechnical Design Manual
4. Route Selection Manual
5. Pavement Design Manual Volume I Flexible Pavements
6. Pavement Design Manual Volume II Rigid Pavements
7. Pavement Rehabilitation and Asphalt Overlay Design Manual
8. Drainage Design Manual
9. Bridge Design Manual
10. Low Volume Roads Design Manual
11. Standard Environmental Procedures Manual
12. Standard Technical Specifications
13. Standard Detailed Drawings
14. Standard Bidding Documents for Road Work Contracts – A series of Bidding
Documents covering a full range from large scale projects unlimited in value to minor
works with an upper threshold of $300,000. The higher level documents have both
Local Competitive Bidding and International Competitive Bidding versions

These documents are available to registered users through the ERA website:
www.era.gov.et

Manual Updates

Significant changes to criteria, procedures or any other relevant issues related to new
policies or revised laws of the land or that is mandated by the relevant Federal Government
Ministry or Agency should be incorporated into the manual from their date of
effectiveness.

Other minor changes that will not significantly affect the whole nature of the manual may
be accumulated and made periodically. When changes are made and approved, new
page(s) incorporating the revision, together with the revision date, will be issued and
inserted into the relevant chapter.

All suggestions to improve the draft manual should be made in accordance with the
following procedures:

Page ii Ethiopian Roads Authority
Site Investigation Manual – 2013 Preface

1. Users of the manual must register on the ERA website: www.era.gov.et
2. Proposed changes should be outlined on the Manual Change Form and forwarded with
a covering letter of its need and purpose to the Director General of the Ethiopian Roads
Authority.
3. Agreed changes will be approved by the Director General of the Ethiopian Roads
Authority on recommendation from the Deputy Director General (Engineering
Operations).
4. The release date will be notified to all registered users and authorities.

Addis Ababa, 2013

Zaid Wolde Gebriel
Director General, Ethiopian Roads Authority

Ethiopian Roads Authority Page iii
Preface Site Investigation Manual – 2013

ETHIOPIAN ROADS AUTHORITY
CHANGE CONTROL DESIGN MANUAL

This area to be completed by the ERA
MANUAL CHANGE
Director of Quality Assurance
Manual Title:____________________________ CHANGE NO._____________
_______________________________________ (SECTION NO. CHANGE NO.
_________________________
Section
Table
Explanation Suggested Modification
Figure
Page

Submitted by:
Name:____________________________________Designation:______________________________
Company/Organisation Address
____________________________________________________________________
_______________________________________email:__________________________Date:________
Manual Change Action
Authority Date Signature Recommended Action Approval
Registration
Director Quality Assurance
Deputy Director General Eng.Ops

Approval / Provisional Approval / Rejection of Change:

Director General ERA:__________________________________ Date: __________________

Page iv Ethiopian Roads Authority
Site Investigation Manual – 2013 Acknowledgements

ACKNOWLEDGEMENTS

The Ethiopian Roads Authority (ERA) wishes to thank the UK Government’s Department
for International Development (DFID) through their Africa Community Access
Programme (AFCAP) for their support in developing this Site Investigation Manual –
2013. The manual will be used by all authorities and organisations responsible for the
provision of roads in Ethiopia.
This Site Investigation Manual-2013 is based on a review of local and international
procedures and is based largely on ERA’s Site Investigation Manual – 2002 but includes
improvements and extensions to deal with topics that were not included in the earlier
manual. This manual also contains relevant parts of ERA’s Low Volume Roads Design
Manual.
From the outset, the approach to the development of the manual was to include all sectors
and stakeholders in Ethiopia. The input from the international team of experts was
supplemented by our own extensive local experience and expertise. Local knowledge and
experience was shared through review workshops to discuss and debate the contents of the
draft manual. ERA wishes to thank all the individuals who gave their time to attend the
workshops and provide valuable inputs to the compilation of the manual.
In addition to the workshops, Peer Review Groups comprising specialists drawn from
within the local industry were established to provide advice and comments in their
respective areas of expertise. The contribution of the Peer Group participants is gratefully
acknowledged.
The final review and acceptance of the document was undertaken by an Executive Review
Group. Special thanks are given to this group for their assistance in reviewing the final
draft of the document.
Finally, ERA would like to thank Crown Agents for their overall management of the
project
As with the other manuals of this series, the intent was, where possible, and in the interests
of uniformity, to use those tests and specifications included in the AASHTO and/or ASTM
Materials references. Where no such reference exists for tests and specifications mentioned
in this document, other references are used.

Executive Review Group
No. Name Organization
1 Amare Assefa, Ato Ethiopian Roads Authority
2 Daniel Nebro, Ato Ethiopian Roads Authority

Ethiopian Roads Authority Page v
Acknowledgements Site Investigation Manual – 2013

List of Persons Contributing to Peer Group Review
No. Name Organization
1 Abebe Asefa, Ato Ethiopian Roads Authority
2 Alemayehu Ayele, Ato Ethiopian Roads Authority
3 Asnake Haile, Ato OMEGA Consulting Engineers
4 Asrat Sewit, Ato Saba Engineering
5 Colin Gourley, Dr. ERA/DRID
6 Daniel Nebro, Ato Ethiopian Roads Authority
7 Efrem Degefu, Ato BEACON Consulting Engineers
8 Fikert Arega, W/ro Ethiopian Roads Authority
9 Muse Belew, Ato Ethiopian Roads Authority
10 Shimelis Tesfaye, Ato Spice Consult
11 Tewodros Alene, Ato Ethiopian Roads Authority
12 Zerihun Nuru, Ato Gondwana Engineering

Project Team
No. Name Organization Role
AFCAP Coordinator for
1 Bekele Negussie ERA
Ethiopia
2 Abdo Mohammed ERA Project Coordinator
3 Frew Bekele ERA Project Coordinator
4 Lulseged Ayalew AFCAP/Crown Agents Lead Author
5 Robert Geddes AFCAP/Crown Agents Technical Manager
6 Les Sampson AFCAP/Crown Agents Technical Director

Addis Ababa, 2013

Zaid Wolde Gebriel
Director General, Ethiopian Roads Authority

Page vi Ethiopian Roads Authority
Site Investigation Manual – 2013 Table of Contents

TABLE OF CONTENTS

FOREWORD........................................................................................................................ I
PREFACE .......................................................................................................................... II
ACKNOWLEDGEMENTS ..................................................................................................... V
TABLE OF CONTENTS ..................................................................................................... VII
LIST OF FIGURES ............................................................................................................. XI
LIST OF TABLES.............................................................................................................. XII
GLOSSARY OF TERMS .................................................................................................... XIV
ABBREVIATIONS AND ACRONYMS................................................................................XVIII
1 INTRODUCTION ...................................................................................................... 1-1
1.1 Background and Context .................................................................................. 1-1
1.2 Objectives ........................................................................................................ 1-2
1.3 Scope ............................................................................................................... 1-3
1.4 Stages of Site Investigation ............................................................................... 1-3
1.5 Approach .......................................................................................................... 1-4
1.6 Manual Structure .............................................................................................. 1-4
1.7 Types of road projects ...................................................................................... 1-6
1.7.1 New Construction ................................................................................... 1-6
1.7.2 Rehabilitation ......................................................................................... 1-7
1.7.3 Reconstruction (including upgrading) ..................................................... 1-7
1.8 The Site Investigation Team ............................................................................. 1-8
1.9 Other Factors .................................................................................................... 1-8
1.9.1 Health, Safety and the Environment ........................................................ 1-8
1.9.2 Site Access .............................................................................................. 1-8
1.9.3 Presence of Existing Services .................................................................. 1-8
1.9.4 Security ................................................................................................... 1-9
1.9.5 Socio-political considerations ................................................................. 1-9
1.9.6 Proximity to Existing Roads and Waterways ........................................... 1-9
2 PHYSIOGRAPHY, CLIMATE, GEOLOGY AND SOIL DISTRIBUTIONS ........................... 2-1
2.1 Introduction ...................................................................................................... 2-1
2.2 Physiography and landform .............................................................................. 2-1
2.3 Climate ............................................................................................................. 2-3
2.3.1 Climatic Zones ........................................................................................ 2-3
2.3.2 Climatic Indices ...................................................................................... 2-5
2.4 Geology ............................................................................................................ 2-6
2.5 Soil type and distribution .................................................................................. 2-8
2.6 Land cover and land use ................................................................................. 2-12
3 INVESTIGATION METHODS AND TECHNIQUES ....................................................... 3-1
3.1 Introduction ...................................................................................................... 3-1
3.2 Topographic and thematic maps ....................................................................... 3-2
3.3 Remote Sensing ................................................................................................ 3-2
3.4 Geophysical methods ........................................................................................ 3-4
3.5 Seismic refraction ............................................................................................. 3-6

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Table of Contents Site Investigation Manual – 2013

3.6 Electrical resistivity........................................................................................... 3-7
3.7 Pits and Trenches .............................................................................................. 3-7
3.8 Boring ............................................................................................................... 3-9
3.8.1 Auger boring ......................................................................................... 3-11
3.8.2 Wash type boring ................................................................................... 3-12
3.8.3 Rotary wash boring ............................................................................... 3-12
3.8.4 Drilling in rock ...................................................................................... 3-12
3.9 Pit, Trench and Boring Logs ........................................................................... 3-13
3.10 Sampling ......................................................................................................... 3-15
3.11 In-situ tests...................................................................................................... 3-17
4 SOIL AND ROCK DESCRIPTION AND CLASSIFICATION ............................................ 4-1
4.1 Introduction ...................................................................................................... 4-1
4.2 Soil description ................................................................................................. 4-1
4.3 Coarse grained soils .......................................................................................... 4-2
4.4 Fine grained soils .............................................................................................. 4-2
4.5 Soil classification .............................................................................................. 4-5
4.6 Engineering characteristics of soils ................................................................... 4-9
4.6.1 Coarse grained soils ................................................................................ 4-9
4.6.2 Fine grained soils .................................................................................. 4-10
4.7 Rock ............................................................................................................... 4-10
4.7.1 Description ............................................................................................ 4-10
4.7.2 Rock name ............................................................................................. 4-11
4.7.3 Lithological descriptions ....................................................................... 4-11
4.7.4 Rock colour ........................................................................................... 4-14
4.7.5 Bedding ................................................................................................. 4-14
4.7.6 Weathering ............................................................................................ 4-15
4.7.7 Rock strength......................................................................................... 4-16
4.7.8 Rock discontinuity ................................................................................. 4-17
5 SITE INVESTIGATION STAGES ................................................................................. 5-1
5.1 Introduction ...................................................................................................... 5-1
5.2 Desk study ........................................................................................................ 5-1
5.2.1 Identifying sources of information ........................................................... 5-1
5.2.2 Reviewing available information ............................................................. 5-3
5.3 Reconnaissance survey ...................................................................................... 5-5
5.4 Preliminary site investigation ............................................................................ 5-5
5.5 Final site investigation ...................................................................................... 5-6
6 DESIGN DATA SURVEYS.......................................................................................... 6-1
6.1 Introduction ...................................................................................................... 6-1
6.2 Sub-grade characterization ................................................................................ 6-2
6.2.1 Location and spacing of test pits and borings .......................................... 6-2
6.2.2 Depth of test pits and boreholes ............................................................... 6-5
6.2.3 Laboratory testing ................................................................................... 6-5
6.2.4 Subsurface profile ................................................................................... 6-8
6.3 Road Cuts and Embankments ............................................................................ 6-9
6.3.1 Road cuts .............................................................................................. 6-10
6.3.2 Embankments ........................................................................................ 6-13
6.4 River crossings................................................................................................ 6-16
6.4.1 Bridges .................................................................................................. 6-17

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6.4.2 Subsurface investigation ....................................................................... 6-17
6.4.3 Footings................................................................................................ 6-21
6.4.4 Driven Piles .......................................................................................... 6-21
6.4.5 Drilled Shafts ........................................................................................ 6-22
6.4.6 Potential scour depth ............................................................................ 6-24
6.4.7 Inspection of existing bridges ................................................................ 6-24
6.4.8 Culverts ................................................................................................ 6-25
6.4.9 Low water crossings ............................................................................. 6-26
7 SPECIAL INVESTIGATIONS ..................................................................................... 7-1
7.1 Introduction ...................................................................................................... 7-1
7.2 Landslides ........................................................................................................ 7-1
7.2.1 Types of landslides .................................................................................. 7-2
7.2.2 Depths of landslides ................................................................................ 7-4
7.2.3 The role of groundwater.......................................................................... 7-5
7.2.4 Landslide mapping .................................................................................. 7-6
7.2.5 Exploration and sampling ....................................................................... 7-7
7.2.6 Monitoring .............................................................................................. 7-9
7.3 Expansive soils ............................................................................................... 7-10
7.3.1 Identification......................................................................................... 7-11
7.3.2 Laboratory tests .................................................................................... 7-14
7.4 Collapsible soils ............................................................................................. 7-14
7.4.1 Identification......................................................................................... 7-15
7.4.2 Strength ................................................................................................ 7-15
7.4.3 Collapse potential ................................................................................. 7-16
7.5 Dispersive soils .............................................................................................. 7-17
7.5.1 Laboratory tests .................................................................................... 7-18
7.5.2 Field identification ................................................................................ 7-19
7.6 Colluvial soils................................................................................................. 7-20
7.6.1 Exploration techniques ......................................................................... 7-21
7.6.2 Engineering characteristics .................................................................. 7-22
7.7 Lateritic soils .................................................................................................. 7-23
7.7.1 Identification......................................................................................... 7-23
7.7.2 Special properties ................................................................................. 7-24
7.8 Saline soils ..................................................................................................... 7-25
7.9 Degradable rocks ............................................................................................ 7-26
7.10 Groundwater................................................................................................... 7-28
7.11 Wetlands ........................................................................................................ 7-32
7.12 Disposal sites .................................................................................................. 7-33
8 CONSTRUCTION MATERIAL SURVEYS ................................................................... 8-1
8.1 Introduction ...................................................................................................... 8-1
8.2 Investigation procedures ................................................................................... 8-1
8.2.1 Aerial photographs ................................................................................. 8-3
8.2.2 Pits and borings ...................................................................................... 8-4
8.3 Material types ................................................................................................... 8-5
8.3.1 Common Fill ........................................................................................... 8-5
8.3.2 Sub-grade and capping layer .................................................................. 8-6
8.3.3 Unbound granular pavement materials ................................................... 8-6
8.3.4 Bitumen-Bound Granular Layers and Surfacing Aggregates ................... 8-7

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