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Ride QualitySmooth Sailing or Fasten
Your Seat Belts?
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
California Asphalt Pavement Association – Ontario – April 20, 2016
Photo courtesy of Tom Massaro
The Case for Smoothness
• Lower fuel consumption
• Less pollution
• Less vehicle wear and tear and damage
• Less damage to freight
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
• Less damage to freight
• Less pavement damage from vehicle dynamics
• Happier traveling public
• More money for roads!!!
Why Now?
• Always have had some ride quality
requirements
– Buyer’s impression
– Straightedge
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– Straightedge
– Profilograph
International Roughness Index
• Improved technology makes it possible
• FHWA initiative
– Increase pavement life
– Decrease user costs
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– Decrease user costs
– Improve public perception
The Key Differences
• Measuring actual profile rather than looking
for deviations over 12’ or 25’
• Simulating profile’s effect on vehicle
response
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response
– Unsprung components
– Suspension / vehicle / occupant response
About 7’ About 50’
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The “Wheel Hop” End We Understand
• Shorter wavelength roughness is easy
– Rotomill can take it out
– Paver can take it out
– Straightedge can find it (usually)
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– Straightedge can find it (usually)
– Profilograph can find it
– Diamond grinder can find it
Longer Wavelength / Dynamics
• Longer than the tools we use
• Can’t “see” them
– Have to rely on ProVAL software
• Simulated vehicle dynamics affect the result
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• Simulated vehicle dynamics affect the result
What It Boils Down To:The time, effort, and money spent to achieve a
given level of final ride quality depends on:
– The pre-construction ride quality for overlays
– The number and types of opportunities for
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
– The number and types of opportunities for improvement
– The practices employed at each opportunity
It is no longer just a matter of grinding bumps after paving.
How Important is This Change?
• Disputes & Claims in the millions
• Claim amount exceeding the original contract
amount
• Grinding costs equivalent to adding an
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• Grinding costs equivalent to adding an
additional 0.10’ overlay over the entire
project
How Can You Succeed?
• Be aware of every opportunity for ride
quality improvement
• Know best practices
• Implement best practices
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
• Implement best practices
• Monitor your work – know what you can and
cannot accomplish
• Be concerned and willing to learn
Opportunities for Improvement
• Corrections applied to existing surface
• Cold milling
• Cold-In-Place Recycling
• Intermediate lifts
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• Intermediate lifts
• Corrections applied to intermediate lifts
• Final lift
• Corrections applied to final lift
Leveling Course
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Pre-paving Grind
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Leveling Course Followed by Grinding
More than one removal option
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What you pave on matters
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307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
What you pave on matters
What you pave on matters
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Best Practices - General
• CONSISTENCY IS KEY
• Maintain constant speed – DO NOT STOP
– Milling
– CIR
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– CIR
– Paving
Best Practices - General
• Balance operation
– Mix production
– Haul
• To the paver, from the coldmill
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– Paver / Coldmill speed
– Compaction of mix
• Hot
• Warm
• Cold
Best Practices -
General• Use as long an averaging reference as
possible
– Sensors at each end of the cold mill
– Ski
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– Ski
– Mat referencer
– Long-wheelbase grinder
• Control cross-slope as well as profile
Best Practices - General
• Reference as smooth a surface as possible
– Existing surface
– Previously-ground or placed lane
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Best Practices – Milling
• Consistent maintenance
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• Consistent maintenance
– Blocks and teeth
– Referencing equipment
– Machine in general
• May want fine or micro-milling, especially for
single, thin overlays
Best Practices – Leveling Course
• Choose an appropriate mix
• Make sure you have adequate time to
compact
– Thin lifts cool very quickly – Multicool
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– Thin lifts cool very quickly – Multicool
recommended
• Use pneumatic rollers
– Steel drums will bridge
Best Practices – CIR
• Verify existing conditions for consistency
• Have a choice to make:
– Constant depth
• More consistent material
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• More consistent material
• Little to no ride quality improvement
– Variable depth – profile correction
• Less consistent material
• Can improve ride quality significantly
Photo courtesy of Darren Coughlin
Best Practices – CIR
• You can grind bumps on CIR
– Make sure recompaction is good before grinding
– May need to grind in cooler conditions (i.e.
nights or mornings)
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nights or mornings)
– Focus on high spots, not dips
– Choose tool and timing carefully
• Some have reported raveling of ground surface when
exposed to traffic for extended periods
• Remember – CIR is not HMA
Photo courtesy of Darren Coughlin
Best Practices –
Paving
• Choose an appropriate mix
• Control mix properties
– Gradation
– Binder content
– Temperature
– Segregation
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Best Practices – Paving
• Balance production / haul / placement /
compaction
• Monitor time available to compact
– Multicool
– May need to adjust for changing conditions
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
– May need to adjust for changing conditions
Best Practices – Paving
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
• Minimize contact with the paver
– Windrow paving
– Material transfer device / vehicle
Best Practices – Paving• Avoid thermal and mechanical segregation in
the hopper
– Either fold the wings after every load, or never fold
them
– Do not run the hopper below half full
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– Do not run the hopper below half full
Best Practices – Paving
• If end dumping
– Do not back into the paver – let the paver pick up
the truck
– “Break” the load before releasing the end gate
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– “Break” the load before releasing the end gate
– Flood the hopper
Best Practices –
Paving
Do not allow
material to
overflow
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overflow
Best Practices – Paving
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
• Set flow gates to allow for balanced flow and
steady flight chain operation
– If paver is not centered on pass, adjust
accordingly
Best Practices – Paving
• Use auger and tunnel extensions as necessary
• Use material management / anti-segregation
baffles / chain curtains / etc.
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
Best Practices – Paving
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
Maintain a constant (and proper) head of
material ahead of the screed
Best Practices – Paving
• Create as straight a joint as possible
– Stringline and guide
– If you cut the longitudinal joint back, cut it in a
straight line
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straight line
• Pave in constant widths as much as possible
• If you have to adjust widths, do it slowly and
adjust material flow
Best Practices –
Paving
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• Minimize raking
• Do not walk on the mat
Best Practices –
Paving
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
• Do not park the rollers on the mat
• Reverse roller direction at an angle
• Control roller speed, particularly on turns
Best Practices – Paving
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• Use a straightedge on construction joints
• Leave enough manpower and material to
build the joint
Reasonable Expectations
• Ride quality after any given opportunity for
improvement
– Depends on the existing ride quality
– Will generally be no better than about 60% of
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
– Will generally be no better than about 60% of
pre-operation ride quality
• You results may vary – you need to know
what you can accomplish.
Reasonable Expectations
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• Leveling course
– Generally less improvement than overlay
– Can be improved with stringline / cuts & fills
• Remember differential compaction
– You can grind or mill leveling courses
Reasonable Expectations
• Cold-In-Place recycling
– MRI of 80 to 90 inches per mile is possible
• Assuming good paving practices
• Assuming good recompaction
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• Assuming good recompaction
Photo courtesy of Darren Coughlin
Reasonable Expectations
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• Cold milling
– About 60% of pre-milling ride quality is possible
– Requires grade control and good reference
– Requires grinding for ride, not production
– May require fine or micro texture
Reasonable Expectations
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• Bump grinding
– Difficult to fix low spots
– Deep grinds are slow, create more disposal, and
may run afoul of specifications
– Longer wheelbase can help
Reasonable Expectations
• Paving
– About 60% of pre-paving ride quality is possible
– Can be considerably less if pre-paving ride quality is
high
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high
– Depends on paving practices used
Reasonable Improvement from FHWA FP-03:
– Single lift – 12-26 percent improvement
– Multiple lifts – 34-43 percent improvement
New construction should yield 60-65 in/mi final MRI
Reasonable Expectations
• ProVAL Smoothness Assurance Module
– 2D simulation of a 3D situation
– Assumes precise depth control of grinder
– Grinder must be accurately input
• Results for an 18’ wheelbase will not match the
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• Results for an 18’ wheelbase will not match the simulation for a 25’ wheelbase grinder
– Does not account for grinder wear, ability to transition, tendency to ride out of cut, etc.
– Accurate locations of grinds are essential – use GPS, not just the DMI
– Dependant on who runs the grinding simulation
So…
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Be careful
So…
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
Pay attention to details
So…
• Look at what you are paving on
• Look at every opportunity to improve ride
quality
307-213-0223 [email protected] © Mike Robinson, PE307-213-0223 [email protected] © Mike Robinson, PE
quality
• Use best practices
• Know what you can and cannot accomplish