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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Ride Quality
California Asphalt Pavement Association – Sacramento – October 28-29, 2015
Smooth Sailing or Fasten Your Seat Belts?
Photo courtesy of Tom Massaro
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
The Case for Smoothness
• Lower fuel consumption• Less pollution• Less vehicle wear and tear and damage• Less damage to freight• Less pavement damage from vehicle
dynamics• Happier traveling public• More money for roads!!!
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Why Now?
• Always have had some ride quality requirements– Buyer’s impression– Straightedge– Profilograph
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
International Roughness Index
• Improved technology makes it possible• FHWA initiative– Increase pavement life– Decrease user costs– Improve public perception
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
The Key Differences
• Measuring actual profile rather than looking for deviations over 12’ or 25’
• Simulating profile’s effect on vehicle response– Unsprung components– Suspension / vehicle / occupant response
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
About 7’ About 50’
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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)– Profilograph can find it– Diamond grinder can find it
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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
improvement– The practices employed at each opportunity
It is no longer just a matter of grinding bumps after paving.
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
How Important is This Change?
• Disputes & Claims in the millions• Claim amount exceeding the original contract
amount• Grinding costs equivalent to adding an
additional 0.10’ overlay over the entire project
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
How Can You Succeed?
• Be aware of every opportunity for ride quality improvement
• Know best practices• Implement best practices• Monitor your work – know what you can and
cannot accomplish• Be concerned and willing to learn
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Opportunities for Improvement
• Corrections applied to existing surface• Cold milling• Cold-In-Place Recycling• Intermediate lifts• Corrections applied to intermediate lifts• Final lift• Corrections applied to final lift
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Leveling Course
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Pre-paving Grind
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Leveling Course Followed by Grinding
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
More than one removal option
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
What you pave on matters
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices - General
• CONSISTENCY IS KEY• Maintain constant speed – DO NOT STOP– Milling– CIR– Paving
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices - General• Balance operation– Mix production– Haul • To the paver, from the coldmill
– Paver / Coldmill speed– Compaction of mix• Hot• Warm• Cold
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices - General
• Use as long an averaging reference as possible– Sensors at each end of the cold mill– Ski– Mat referencer– Long-wheelbase grinder
• Control cross-slope as well as profile
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices - General
• Reference as smooth a surface as possible– Existing surface– Previously-ground or placed lane
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Milling
• Consistent maintenance – Blocks and teeth– Referencing equipment– Machine in general
• May want fine or micro-milling, especially for single, thin overlays
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Leveling Course
• Choose an appropriate mix• Make sure you have adequate time to
compact– Thin lifts cool very quickly – Multicool
recommended• Use pneumatic rollers– Steel drums will bridge
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – CIR
• Verify existing conditions for consistency• Have a choice to make:– Constant depth• 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
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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)– 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 HMAPhoto courtesy of Darren Coughlin
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
• Choose an appropriate mix• Control mix properties– Gradation– Binder content– Temperature– Segregation
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving• Balance production / haul / placement /
compaction• Monitor time available to compact– Multicool– May need to adjust for changing conditions
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
• Minimize contact with the paver– Windrow paving– Material transfer device / vehicle
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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– Flood the hopper
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
Do not allow material to overflow
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
• Set flow gates to allow for balanced flow and steady flight chain operation– If paver is not centered on pass, adjust
accordingly
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
• Use auger and tunnel extensions as necessary
• Use material management / anti-segregation baffles / chain curtains / etc.
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
Maintain a constant (and proper) head of material ahead of the screed
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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• Pave in constant widths as much as possible• If you have to adjust widths, do it slowly and
adjust material flow
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
• Minimize raking• Do not walk on the mat
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
• Do not park the rollers on the mat• Reverse roller direction at an angle• Control roller speed, particularly on turns
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Best Practices – Paving
• Use a straightedge on construction joints• Leave enough manpower and material to
build the joint
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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
pre-operation ride quality
• You results may vary – you need to know what you can accomplish.
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Reasonable Expectations
• Leveling course– Generally less improvement than overlay– Can be improved with stringline / cuts & fills• Remember differential compaction
– You can grind or mill leveling courses
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Reasonable Expectations
• Cold-In-Place recycling– MRI of 80 to 90 inches per mile is possible • Assuming good paving practices• Assuming good recompaction
Photo courtesy of Darren Coughlin
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Reasonable Expectations
• 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
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Reasonable Expectations
• Bump grinding– Difficult to fix low spots– Deep grinds are slow, create more disposal, and
may run afoul of specifications– Longer wheelbase can help
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Reasonable Expectations
• Paving– About 60% of pre-paving ride quality is possible– Can be considerably less if pre-paving ride quality is
high– Depends on paving practices used
Reasonable Improvement from FHWA FP-03:– Single lift – 12-25 inches/mile improvement– Multiple lifts – 34-43 in/mi improvementNew construction should yield 60-65 in/mi final MRI
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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
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
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
So…
Be careful
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
So…
Pay attention to details
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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
So…
• Look at what you are paving on• Look at every opportunity to improve ride
quality• Use best practices• Know what you can and cannot accomplish