Docstoc

TITLE SLIDE IN CAPS HERE

Document Sample
TITLE SLIDE IN CAPS HERE Powered By Docstoc
					 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
   Relationship between variables
Y = (say) roughness after 5 years
      Poor
                                    




                             
               

     Good

                                        x
   Relationship between variables
Y = (say) roughness after 5 years

      Poor
                                    




                             
               

      Good

                                        x
              Multi-value problem
Y = (say) roughness after 5 years
      Poor

          




                       

     Good

                                    Plasticity Index
             Multi-value problem
Y = (say) roughness after 5 years
      Poor
                                                




                         

     Good

                                    Plasticity Index
              Multi-value problem
  Y = (say) roughness after 5 years
Poor
                                                  
                                     Very wet




                                          Very dry

Good

                                       Plasticity Index
    High traffic (conventional)

   traffic level                          3
   subgrade strength                      3
   base type                              3
   base layer thickness                   3
   base layer strength (for some types)   2
   sub-base layer thickness               3
   sub-base type                          2
   surface layer thickness                3
   surface type                           3
   climate                                3
                                           26,244
      THE ROAD DESIGN OR “RISK” ENVIRONMENT

                            PREVAILING CLIMATE             TRAFFIC CHARACTERISTICS
                            Rainfall (intensity,           Axle loading
DRAINAGE AND
                            distribution)                  Tyre pressures
HYDROLOGY
                            Temperature (evaporation &     Seasonality
Ground & surface
                            diurnal change)                Position           MAINTENANCE
water flow
                            Future change or               Growth projections Capacity & skills
Hydro-genesis
Demand of terrain           unpredictability                                      Funding
Modifying influences                                                              Programming

GEOMETRICS AND                                                          CONSTRAINTS OF THE
                                             OPTIMUM OR
CROSS-SECTION PROFILES                                                  “GREEN” ENVIRONMENT
Road width                                  APPROPRIATE                 Constrained alignments
Crown height                                  PAVEMENT                  Access to materials
Demand of terrain                              DESIGN                   Depletion of resources
Sealed shoulders                            METHODOLOGY                 Terrain stability

OTHER
Technology solution                                                 AVAILABLE MATERIALS
      •labour based                                                 Alternative & thin bituminous
      •Intermediate equip                                           surfacings
                                CONSTRUCTION
•Safety                                                             Pavement materials
                                Quality control
•Institutional environment                                                •Marginal materials
                                Capacity, training & experience
capacity                                                                  •Standards
                                Selection and use of plant
•Financing                                                          •Subgrade & road formation
                                Influence of construction traffic
•Political pressure                                                 •Problem soils
•Design period                                                      •Moisture sensitivity
•Road side activity                                                 •Stabilisation options and treatments
            Pass/fail criteria

Number of
samples


                 Specification
                 for trunk road




               Strength of material
                      Low traffic
   traffic level                         3
   subgrade strength                     3
   base type                             6
   base layer thickness                  3
   base layer strength (for all types)   3
   sub-base layer thickness              3
   sub-base type                         3
   surface layer thickness               3
   surface type                          4
   climate                               3
   technology                            2
   maintenance                           2
   cross section and geometry            4
   drainage                              3
   ++
                                          2 million at least
 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 ?


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
      EQUIVALENT THICKNESS De, INCHES
45
                                                                                          x
40                                                                          x        x   x x
                                                                                xx             x
35                                                                   x      x
                                                                                      x
                                                                                  x x x
                                                                                  x
                                                            x         x x       x
                                                   x   x    x                       x
30                                                      x             x
                                                                    xx x
                                                       x            x

25                                           x
                                                   x            x    x
                                 x       x

                                 x           x x       x        x
20

15                                   x



10                           x
                        x

 5

 0
     103      104      105           106                                   107                     108
           WEIGHTED EQUIVALENT ESA APPLICATIONS
AASHO "DESIGN" EQUATION COMPARED WITH DATA
       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
 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
A few observations
  Variability and improving
         technology
 do not knock belts and braces
 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



 Catalogue of structures?
 Graphs
?
 Think about it
The end for now
   Consideration of the Road Design
       Environment for LVSR’s
                         PREVAILING
   DRAINAGE AND           CLIMATE
   HYDROLOGY

                                          AVAILABLE
GEOMETRICS AND                            MATERIALS
CROSS-SECTION      OPTIMUM OR
  PROFILES         APPROPRIATE
                    PAVEMENT               TRAFFIC
OTHERS                                     CHARACTERISTICS
                     DESIGN
    MAINTENANCE                        CONSTRUCTION


                  CONSTRAINTS OF THE
                       “GREEN”
                     ENVIRONMENT
DRAINAGE AND HYDROLOGY


 Ground water
 Surface water
 Drainage design
 Permeability of pavement layers
 Surface infiltration
 Hydro-genesis
                CLIMATE



 Rainfall (intensity, distribution)
 Temperature (evaporation & diurnal
  change)
         CONSTRUCTION


 Technology and selection and use of
  plant
 Quality control and realistic variability
 Influence of construction traffic (intensity,
  distribution)
       MAINTENANCE


 Capacity and skills
 Funding
 Programming (likely timing)
            MATERIALS

 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

 Road width
 Sealed shoulders or not
 Embankment height
 Camber
                 TRAFFIC

 Axle loading
 Tyre pressures
 Seasonality
 Position on carriageway
 Vehicle types
 NMT
 Growth

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:8
posted:3/2/2012
language:
pages:30