PROJECT OVERVIEW

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PROJECT OVERVIEW N3/3 ATHLONE TO HILTON Dennis
Rossmann
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N3/3 ATHLONE TO HILTON
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CONTRACT No NRA N0303012/6 REHABILITATION OF
ROUTE 3, SECTIONS 3 4 ATHLONE TO HILTON km
19,130 (N3/3) TO km 1,160 (N3/4)
CONTRACT DETAILS Employer
SANRAL Contractor Basil Read /
Milling Techniks Consortium Consulting
Engineers BLN Consortium (Ingérop Africa,
Letsunyane
Associates (Pty) Ltd and
Preben Naidoo Associates) Tender Sum
R65 535 800-64
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CONSTRUCTION HISTORY
Construction by Provincial Roads Department NBC
commenced 1957 completed 1962 SBC completed
1971 Subsequent reseal and overlay
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TRAFFIC
ADT 22 560 ADTT 3058
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TOPOGRAPHY
Grades 7 max Up to 6 over 40 of
length Superelevation Up to 12
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TRAFFIC ACCOMMODATION
Closures to one lane limited to outside peak
periods Two lanes open in each direction outside
working hours Facility for removal of broken down
vehicles
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GEOTECHNICAL INSTABILITY
Infilled gullies Talis creep Requires continuous
management
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PAVEMENT DESIGN
Rigid pavement overlay Block paving Flexible
pavement (Asphalt overlay) Composite pavement
(Concrete / asphalt)
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COMPOSITE PAVEMENT

• Appropriate pavement
• Cost benefit
• Labour enhancement

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CRCP INLAY EXPERIENCE

• Riding quality / smoothness
• Longitudinal joint ( rigid / flexible)
• Pop-outs
• Subsurface drainage

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QUALITY CONTROL
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GEOMETRIC DESIGN Peter Unstead
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• GEOMETRIC DESIGN PHILOSOPHY
• PARTIAL CONCRETE INLAYS TO PRESCRIBED LEVELS
• FINISHED ROAD LEVEL TO BE RAISED ENABLING
• SMOOTHING OF VERTICAL ALIGNMENT
• ELIMINATION OF UNDULATIONS CAUSED BY FILL
  SUBSIDENCES
• REGULARISATION OF THE SUPERELEVATION TO A
  LIMITED EXTENT
• CARRIAGEWAYS TO BE WIDENED WITHIN GEOTECHNICAL
  AND BUDGET CONTSTRAINTS

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• HORIZONTAL AND VERTICAL ALIGNMENT
• CARRIAGEWAYS HAD BEEN CONSTRUCTED IN SEPARATE
  SECTIONS UNDER VARIOUS CONTRACTS AND OVER AN
  EXTENDED PERIOD OF TIME
• A TRULY GEOMETRICAL MODEL OF THE VERTICAL
  ALIGNMENT COULD NOT BE ESTABLISHED WITHOUT
  RESULTING IN EXCESSIVELY THICK OVERLAYS
• EXISTING ROAD LEVELS "SMOOTHED" BY GRAPHICAL
  METHODS
• SUPERELEVATION CORRECTIONS APPLIED
• VARIOUS THICKNESSES OF OVERLAY LESS THE 80mm
  MILLING DEPTH ADDED TO PRODUCE THE FINISHED
  ROAD LEVELS.

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• DESIGN METHODOLOGY
• DETAILED TOPOGRAPHICAL SURVEY USING GPS
  METHODS TO CREATE A DIGITAL TERRAIN MODEL OF THE
  EXISTING ROAD AND WIDENING AREAS.
• POINTS SURVEYED
• AT EACH EDGE OF ROAD
• ON THE LANE MARKINGS
• IN THE INVERT AND ON THE OUTER EDGES OF THE
  EXISTING SIDE DRAINS.
• A BEST-FIT GEOMETRIC HORIZONTAL ALIGNMENT
  DERIVED FOR EACH CARRIAGEWAY
• THE CENTRE-LINE CHOSEN BETWEEN THE SLOW LANE AND
  THE CENTRE LANE
• THE NBC REALIGNED BETWEEN km 23,2 AND km 23,7 TO
  CONTINUE THE THREE LANE SECTION PAST THE HILTON
  INTERCHANGE BY WIDENING THE CARRIAGEWAY IN THE
  MEDIAN.

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• DESIGN METHODOLOGY
• USING ROAD DESIGN SOFTWARE EXISTING ROAD LEVELS
  DETERMINED ON CENTRE-LINE, FUTURE LANE MARKING
  POSITIONS AND EDGES OF THE CARRIAGEWAY
• LEVELS TRANSFERRED TO A SPREADSHEET
• COLUMN PROVIDED TO ADJUST THE DESIGN CENTRE LINE
  LEVEL RELATIVE TO EXISTING LEVEL TO PRODUCE A
  SMOOTH LONGITUDINAL PROFILE
• EXISTING CROSSFALLS ASSESSED FOR UNIFORMITY WITH
  RESPECT TO LHS AND RHS OF CENTRE LINE AND
  COMPLIANCE WITH STANDARDS.
• DESIGN CROSSFALLS CHOSEN
• DESIGN LEVELS DERIVED AT VARIOUS OFFSETS LEFT AND
  RIGHT OF CENTRE-LINE
• EDGE LEVELS DETERMINED BY THE CROSSFALLS CHOSEN.

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• DERIVATION OF DESIGN LEVELS
• DIFFERENCES BETWEEN EXISTING ROAD LEVELS AND THE
  PROPOSED DESIGN LEVELS CALCULATED AND INFLUENCE
  ON PAVEMENT DESIGN ASSESSED
• THE SMOOTHNESS OF THE LONGITUDINAL PROFILES ON
  CENTRE-LINE AND AT THE EDGES ASSESSED
  GRAPHICALLY BY APPLYING A SLOPING DATUM LINE.
  ADJUSTMENTS APPLIED AND CHECKED UNTIL A
  SATISFACTORY PROFILE WAS OBTAINED.

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SMOOTHING OF LEVELS N3/3 SOUTHBOUND CARRIAGEWAY
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• WIDENING OF THE CARRIAGEWAYS
• EXTENT SUBJECT TO GEOTECHNICAL AND BUDGET
  CONSTRAINTS
• NORTHBOUND CARRIAGEWAY
• BETWEEN RICKIVY VIADUCT AND km 21,2 WIDENING
  WOULD ENTAIL EXTENSIVE EARTHWORKS AND
  RETAINING WALLS
• NORTH OF km 21,2 TO HILTON INTERCHANGE
• TO EASE TRAFFIC CONGESTION, A 3m WIDE SLOW
  SHOULDER WAS MORE ESSENTIAL ON THE LONG
  SUSTAINED 6 GRADE WHERE HEAVY VEHICLES TEND TO
  TRAVEL TWO ABREAST UP TO HILTON
• HEAVY VEHICLES BREAK DOWN MORE OFTEN IN THIS
  AREA THAN FURTHER SOUTH
• THICK MIST MORE PREVALENT

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• WIDENING OF THE CARRIAGEWAYS
• EXISTING 15,1m WIDTH AVAILABLE FROM km 21,7 TO
  km 23,4
• A RELATIVELY FLAT AREA AVAILABLE ON THE RIGHT
  HAND SIDE OF THE NBC TO ALLOW WIDENING IN THE
  MEDIAN AVOIDING WIDENING OF CUTTINGS AND
  CONSTRUCTION OF RETAINING WALLS ON THE LEFT HAND
  SIDE
• EXTENSION OF THE EXISTING 15,1m WIDE SECTION
  BACK TO km 21,2 AND FROM km 23,2 OVER THE RIDGE
  TO THE DOWNGRADE APPROACHING CEDARA COST
  EFFECTIVE DUE TO RELATIVELY MINOR EARTHWORKS
  INVOLVED

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• WIDENING OF THE CARRIAGEWAYS
• SOUTHBOUND CARRIAGEWAY
• LIMITED TO EXTENDING EXISTING 15,1m WIDTH FROM
  km 24,7 TO km 25,5 AT HILTON
• HEAVY VEHICLES GENERALLY CONFINED TO CRAWLER
  LANE BETWEEN RICKIVY VIADUCT AND HILTON
• HEAVY VEHICLES SELDOM BREAK DOWN
• WIDENING THE 12,0m WIDE CARRIAGEWAY BETWEEN km
  21,2 AND km 22,9 CONSTRAINED BY VERY HIGH FILLS
  ON RHS AND THE NEED TO AVOID CUTTING INTO THE
  HILLSIDE ON LHS
• WIDENING OF THE 11,0m WIDE CARRIAGEWAY BETWEEN
  THE ARRESTOR BED AND km 21,2 CONSTRAINED BY DEEP
  SEATED FILL INSTABILITY

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Pavement Design and Details

• Herman Wolff

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PRESENTATION OVERVIEW

• Pavement design principles
• Design traffic
• Pavement models
• Flexible pavement design method
• Rigid pavement design method
• Resulting pavement structures
• Design details

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PAVEMENT DESIGN PRINCIPLES

• CRC partial inlays used in slow lanes
• Slow moving heavy traffic on steep incline
• High ambient temperatures
• CRC to allow for future overlays
• CRC partial inlay in NBC centre lane
• Heavies overtaking on uphill sections
• Joint between slow and centre lanes concrete to
  concrete
• Asphalt base and surfacing used in SBC centre
  lane
• Lower traffic because of dedicated crawler lane
• Easier traffic accommodation.
• Asphalt surfacing used in fast lanes
• Low traffic loading

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DESIGN TRAFFIC

• Cumulative E80s over 15 years
• Slow lanes 40 million
• NBC centre lane 20 million
• SBC centre lane 10 million
• Fast lanes 1 million

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PAVEMENT MODELS

• Derivation of pavement models for mechanistic
  analysis
• As-built information
• Backcalculated elastic layer moduli from FWD
  testing
• Asphalt cores

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FLEXIBLE PAVEMENT DESIGN

• Asphalt and cemented layers
• SAMDM stochastic transfer functions based on
  linear elastic material behaviour and failure in
  fatigue
• Granular layers
• Stochastic transfer functions based on non-linear
  elasto-plastic material behaviour and failure in
  permanent deformation
• Subgrade layers
• Transfer function based on linear elastic
  material behaviour and failure in permanent
  deformation

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ASPHALT
TRH4 Revision (1995) Phase 1 Updating Transfer
Functions for SAMDM.
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RIGID PAVEMENT DESIGN

• Manual M10
• Deterministic
• Nomograms
• Underlying pavement modelled by a single
  semi-infinite layer with an equivalent support
  stiffness
• CNCRISK computer program
• Developed by C and CI
• Stochastic (Monte Carlo Simulation)
• Computerised
• Underlying pavement modelled by multiple layers
  characterised by thickness and stiffness (MPa)

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PAVEMENT STRUCTURES - FLEXIBLE

• Fast lanes
• 30 SMA, 20 40 asphalt levelling layer
• 30 SMA, 60 asphalt base, asphalt levelling layer
• Fast lane widenings
• 30 SMA, 60 asphalt base, 150 C3 subbase, 300 G7
  and G9 selected layers, subgrade (improved)
• SBC middle lane
• 30 SMA, 150 asphalt base
• 30 SMA, 100 asphalt base, 250 C3 subbase
  (reworked)

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PAVEMENT STRUCTURES - RIGID

• Thickness varies between 180 and
• 220 mm depending on loading and support
• 30 mm asphalt bedding layer where no existing
  asphalt
• Existing structure

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INFLUENCE OF SUPPORTING LAYERS
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THANK YOU
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CONSTRUCTIONPhilip Wyatt
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ROAD WIDENING NBC Fast lane and shoulder -
4,0km NBC Slow shoulder -
0,5km SBC Fast shoulder - 0,8km CONCRETE
PAVEMENT NBC Slow shoulder, slow lane and
middle lane 4,5km SBC Slow shoulder and
slow lane - 4,6km Thickness 190 to
220mm Area 75 000m² Volume 16 000m³
Reinforcement 720tonnes
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MILLING 12 000m³ ASPHALT NBC Fast lane and
fast shoulder - 7,0km SBC Middle lane, fast
lane and fast shoulder - 6,3km Bedding
(below concrete) 6 200tonnes Base and
Levelling 17 500tonnes SMA Surfacing 108
000m² DRAINS Concrete for Side Drains 3 560m³
Mass concrete (Make up) 600m³
CONCRETE BARRIERS 6,8km
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GENERAL VIEWS
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ACCOMMODATION OF TRAFFIC
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CONCRETE PAVEMENT
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EVAPORATION RATE DIAGRAM
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CONCRETE RESULTS FORM
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PROFILOGRAPH
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PROFILOGRAPH EQUATION
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PROFILOGRAPH RESULTS
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IN SITU MILLING
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