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THE WAY FORWARD. or. WHO SAID RESEARCH WAS EASY ?. Relationship between variables. Y = (say) roughness after 5 years. Poor. Expectation for acceptable performance. . Good. x. Relationship between variables. Y = (say) roughness after 5 years. Poor. . . Good. x.

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The way forward

THE WAY FORWARD

or

WHO SAID

RESEARCH WAS EASY ?


Relationship between variables
Relationship between variables

Y = (say) roughness after 5 years

Poor

Expectation for acceptable performance

Good

x


Relationship between variables1
Relationship between variables

Y = (say) roughness after 5 years

Poor

Good

x


Relationship between variables2
Relationship between variables

Y = (say) roughness after 5 years

Poor

Good

x


Relationship between variables3
Relationship between variables

Y = (say) roughness after 5 years

Poor

Good

x


Multi value problem
Multi-value problem

Y = (say) roughness after 5 years

Poor

Good

Plasticity Index


Multi value problem1
Multi-value problem

Y = (say) roughness after 5 years

Poor

Good

Plasticity Index


Multi value problem2
Multi-value problem

Y = (say) roughness after 5 years

Poor

Very wet

Very dry

Good

Plasticity Index


High traffic conventional
High traffic (conventional)

  • 3

  • 3

  • 3

  • 3

  • 2

  • 3

  • 2

  • 3

  • 3

  • 3

  • 26,244

  • traffic level

  • subgrade strength

  • base type

  • base layer thickness

  • base layer strength (for some types)

  • sub-base layer thickness

  • sub-base type

  • surface layer thickness

  • surface type

  • climate


The road design or risk environment
THE ROAD DESIGN OR “RISK” ENVIRONMENT

TRAFFICCHARACTERISTICS

Axle loading

Tyre pressures

Seasonality

Position

Growth projections

PREVAILING CLIMATE

Rainfall (intensity, distribution)

Temperature (evaporation & diurnal change)

Future change or unpredictability

DRAINAGE AND HYDROLOGY

Ground & surface

water flow

Hydro-genesis

Demand of terrain

Modifying influences

MAINTENANCE

Capacity & skills

Funding

Programming

GEOMETRICS AND

CROSS-SECTION PROFILES

Road width

Crown height

Demand of terrain

Sealed shoulders

CONSTRAINTS OF THE “GREEN” ENVIRONMENT

Constrained alignments

Access to materials

Depletion of resources

Terrain stability

OPTIMUM OR APPROPRIATE PAVEMENT DESIGN METHODOLOGY

  • OTHER

  • Technology solution

    • labour based

    • Intermediate equip

  • Safety

  • Institutional environment capacity

  • Financing

  • Political pressure

  • Design period

  • Road side activity

  • AVAILABLE MATERIALS

  • Alternative & thin bituminous

  • surfacings

  • Pavement materials

    • Marginal materials

    • Standards

  • Subgrade & road formation

  • Problem soils

  • Moisture sensitivity

  • Stabilisation options and treatments

CONSTRUCTION

Quality control

Capacity, training & experience

Selection and use of plant

Influence of construction traffic


Pass fail criteria
Pass/fail criteria

Number of

samples

Specification for trunk road

Strength of material


Low traffic
Low traffic

  • 3

  • 3

  • 6

  • 3

  • 3

  • 3

  • 3

  • 3

  • 4

  • 3

  • 2

  • 2

  • 4

  • 3

  • 2 million at least

  • traffic level

  • subgrade strength

  • base type

  • base layer thickness

  • base layer strength (for all types)

  • sub-base layer thickness

  • sub-base type

  • surface layer thickness

  • surface type

  • climate

  • technology

  • maintenance

  • cross section and geometry

  • drainage

  • ++


Basis for the orn31 designs
BASIS FOR THE ORN31 DESIGNS

  • Full scale design and performance experiments carried out by TRL in tropical countries

  • Full scale design and performance experiments carried out by others in tropical countries

  • Performance studies of as-built networks

  • Empirically based performance models

    (eg Highway Design Model III )

  • Theoretical / mechanistic analysis

X


How do we cope
How do we cope ?

Engineering judgement


Engineering judgement
Engineering judgement

  • we cannot do without it

  • but it is all too easy to draw incorrect conclusions so...

  • one man’s judgement is not enough

  • we need to know about variability and reliability

  • to do so we need lots of data


The way forward

103

104

105

106

107

108

EQUIVALENT THICKNESS De, INCHES

45

x

40

x

x

x

x

x

x

x

35

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

30

x

x

x

x

x

x

x

25

x

x

x

x

x

x

x

x

x

x

20

x

15

x

10

x

x

5

0

WEIGHTED EQUIVALENT ESA APPLICATIONS

AASHO "DESIGN" EQUATION COMPARED WITH DATA


Engineering judgement1
Engineering judgement

  • we cannot do without it

  • it is all too easy to draw incorrect conclusions so...

  • one man’s judgement is not enough

  • to evaluate risk we need lots of data

  • consensus necessary - an expert system

  • hence this project


The way forward
The way forward

  • As the projects proceeds there will be many issues to be addressed

  • this meeting has been the ‘literature review’ (as it were)

  • the projects are clearly very ambitious and there is a danger of failing to focus sufficiently on the most important issues

  • we now need to begin to synthesize our experiences to help inform the data collection phase



Variability and improving technology
Variability and improving technology

  • do not knock beltsandbraces

  • specifications can get tighter and better as contractors improve

  • there are usually several ways to solve a problem

  • it may be unnecessary to agonise over which is best - they may be equally (or almost equally) cost effective

  • on the other hand they may not !!!

  • so don’t waste money (John Hine)


And eventually we will need to decide how to present the final output
And eventually we will need to decide how to present the final output

  • Catalogue of structures?

  • Graphs

  • ?

  • Think about it


The end for now

The end for now final output


Consideration of the road design environment for lvsr s
Consideration of the Road Design Environment for LVSR’s final output

PREVAILING

CLIMATE

DRAINAGE AND HYDROLOGY

AVAILABLE MATERIALS

GEOMETRICS AND CROSS-SECTIONPROFILES

OPTIMUM OR APPROPRIATE PAVEMENT DESIGN

TRAFFICCHARACTERISTICS

OTHERS

MAINTENANCE

CONSTRUCTION

CONSTRAINTS OF THE “GREEN” ENVIRONMENT


Drainage and hydrology
DRAINAGE AND HYDROLOGY final output

  • Ground water

  • Surface water

  • Drainage design

  • Permeability of pavement layers

  • Surface infiltration

  • Hydro-genesis


Climate
CLIMATE final output

  • Rainfall (intensity, distribution)

  • Temperature (evaporation & diurnal change)


Construction
CONSTRUCTION final output

  • Technology and selection and use of plant

  • Quality control and realistic variability

  • Influence of construction traffic (intensity, distribution)


Maintenance
MAINTENANCE final output

  • Capacity and skills

  • Funding

  • Programming (likely timing)


Materials
MATERIALS final output

  • Alternative & thin bituminous surfacings

  • Pavement materials

    • Marginal materials

    • Standards

  • Subgrade & road formation

  • Problem soils

  • Moisture sensitivity

  • Stabilisation options and treatments


Geometrics and cross section profiles
GEOMETRICS AND final outputCROSS-SECTION PROFILES

  • Road width

  • Sealed shoulders or not

  • Embankment height

  • Camber


Traffic
TRAFFIC final output

  • Axle loading

  • Tyre pressures

  • Seasonality

  • Position on carriageway

  • Vehicle types

  • NMT

  • Growth