Presentation by Don Matthews, PRS, on the latest with pavement smoothness specifications, technology and challenges in California. Presentation delivered during the CalAPA Fall Asphalt Pavement Conference Oct. 26-27, 2016 in Sacramento, Calif.

1. Update on Pavement Smoothness
In California
CalAPA Fall Asphalt Conference & Equipment Expo
October 27, 2016
Don Matthews, PE
Pavement Recycling Systems, Inc.

2. California’s Smoothness Transition
 Before 2012, pavement
smoothness was measured
using a California
profilograph and straightedge
 After 2012, pavement
smoothness is measured
using the inertial profiler and
straightedge

3. Ride Comfort – Depends On:
 Road Roughness
 Vehicle Response to the Road
 Human Response to Vibration
Profilograph and Inertial Profiler
Inertial Profiler and Subsequent IRI
Calculation
Indirectly Considered via IRI

4. Quarter Car (Golden Car) Filter
©Copyright the U. of Michigan
International Roughness Index
(IRI)
Provides a standardized value that
is determined by obtaining an
accurate measurement of the profile
of the road
Then processing that profile
through an algorithm (ProVAL) that
simulates the way a reference
vehicle (golden car – represents
70% of vehicles) would respond to
the roughness inputs in a single
wheel path

6. No One Debates the Benefits of
Smooth Pavements
Smoother roads:
 Provide a comfortable ride
 Last longer
 Stay smoother longer
 Are safer
 Save money (pavement and vehicle
repairs and fuel economy)
 Are better for the environment

7. In Fact:

8. So Why All the Issues?
Many Claims and Disputes
Large Losses - Both Contractors and State

9. In a Word:
Ignorance
By Most Everyone

10. To Help
Industry and Caltrans together
held a Smoothness Forum 9/28/15
A Smoothness Subtask Group Was Formed
• Working Group - Data Collection/Analyses, Design
Guidance and Specification
• Working Group - Best Paving Practices
• Working Group - ProVAL Training and Smoothness
Corrections

11.  Profilograph Specification
• Profile Index of 2.5 inches per 0.1 mile
• Must Grinds – Localized roughness of 0.3 inch or more in 25 feet
 Inertial Profiler with IRI Specification
• Mean Roughness Index (MRI) – 60 or 75 in/mi depending on depth of HMA
• Area of Localized Roughness (ALR) – 160 in/mi localized roughness based on a
25 feet sliding scale
 They Seem Similar
What the Specification Numbers Meant
Determined That Few Understood:
Concept Maybe Numbers No!

12. Few Understood:
What it took to achieve the new smoothness requirements
during construction
What best paving practices are really required for
smoothness
The Killer Phrase -
“I am not worried about it. I have been paving for 30
years” Get out the checkbook!

13. Consistency - Head of Material on Screed
Consistency - Paving Speed
Consistency - Mix Temperature
Best Paving Practices = Consistency!!!

14. Screed Control – Referencing
What is referenced has a major impact on smoothness
Longer and smoother the reference, the smoother the
pavement
A smooth cold planed surface that was cut with an
averaging system could be a good reference surface as
opposed to a rougher shoulder or adjacent lane
However, if the cold planed surface delaminates another
surface should be used
Once a good reference line is set trust the equipment
.

15. Referencing
Why Correct Here?
If Paver Will Reference Here?

16. Best Paving Practices Training Available
Joint Working Group on Best Paving Practices
Is nearly complete with training module
Expected out by end of the year
CalAPA’s ½ Day Training Class
PAVEMENT SMOOTHNESS ESSENTIALS -- NEW
SPECIFICATIONS, TECHNOLOGY & BEST PRACTICES

17. Also Realized Few Understood:
If smoothness could be achieved for a given roadway
condition using standard design strategies
No Consideration of Roadway Location or Type
Little Consideration to Existing Roughness

18. TYPES OF ROADS
Both Mill and Fill of 0.10’
Both Have a Final MRI Requirement of 75 in/mi
The roadway on the right will likely take much more pre-
paving correction and effort then the left

19. Existing Surface
MRI (in/mi)
New Surface
MRI (in/mi)
300 120
200 90
150 75
120 65
90 60
60 45
*Based Upon One Smoothness Opportunity
Using Best Paving Practices
As Part of the Smoothness Working Group
Industry Provided Reasonable Expected Improvement Values
For Caltran’s Consideration
Additional Rehabilitation Line Items Would Be Provided If Existing MRI “Too Rough” For
Primary Design Strategy
Existing Pavement Grinding or Cold Planing Corrections
Removals and Replacement
Leveling Course etc.
Least agreement on this number

20. Prepave Grinding (Corrections)
As a Strategy
Existing Asphalt Surface Prior to
Overlay
Existing Pavement Surface
Aggregate Base/Subgrade
Pre-pave Grinding or
Cold Planing is a
Smoothness
Opportunity
HMA OverlaySmoothness
Opportunity

21. CalTran’s Specification – Prepaving “Grinding”
 Correct Areas of Localized Roughness HMA >180 in/mi
 Currently Bid by Day with Extra Days Paid as Determined By RE. Any
Areas Not Corrected, Excluded From Final Smoothness Requirements
 Should Come with Inertial Profiler Bid Item
 Overlay’s Only. Not Provided for Cold Planing or CIR
 In the Future Pre-construction Profiles with Electronic Files Provided and
Prepaving Corrections Bid by the Lump Sum?
 Depending on Existing Roughness Corrections May be Necessary Even
Prior to Cold Planing
 Some Concern Over Interpretations

22. Law of diminishing return by surface corrections

23. And Again
Why Correct Here?
If Paver Will Reference Here?

24. Mill and Fill
Cold Planing As A Strategy
Existing Pavement Surface
Aggregate Base/Subgrade
Smoothness
Opportunity?
Filled HMA
Smoothness
Opportunity

25. Cold Planing a Smoothness Opportunity?
There is a Debate!
Do Agree That It is Not Effective if:
Mill depth must be at the specified depth and follow
existing surface
Paving operation does not use milled surface for control
Good paving practices are not utilized

26. Variable Depth Cold Planing Must be Used
Following an existing rough surface at constant depth will transfer the
roughness to the bottom of cold planed surface. Good control systems such
as an averaging system should be used on the existing surface
Variable Depth

27. Good Cold Planing Practices Must Be Followed:
Transitions must be smooth into and out of cuts
The milled surface must be cleaned well
The drum must not be stopped while still in the cut
The mill’s mechanical systems must be maintained
The cutting tools and blocks must be maintained and/or
replaced as needed

28. Appropriate Continuous Speeds Must be Maintained
Do not out run the pattern – It may not be about production
The texture changes as speed increases

29. Must Implement Quality Control - Take Pictures of
Issues and Use Straight Edge

30. Pre Milling Post Milling
MRI
(in/mi)
MRI
(in/mi)
Change in
MRI
%
Change
127 96 31.2 25%
120 98 21.6 18%
74 77 -2.4 -3%
95 94 1.5 2%
83 145 -61.9 -75%
96 101 -4.8 -5%
77 99 -22.7 -29%
88 114 -26.7 -31%
80 128 -48.1 -60%
78 118 -40.0 -52%
86 88 -2.1 -2%
64 112 -47.7 -74%
65 104 -39.0 -60%
90 123 -33.5 -37%
63 91 -27.8 -44%
72 97 -25.1 -35%
101 96 5.0 5%
79 110 -30.4 -38%
61 140 -78.8 -129%
61 113 -51.5 -84%
70 91 -21.2 -30%
71 105 -33.3 -47%
123 130 -7.0 -6%
72 125 -53.0 -74%
81 75 5.3 7%
77 107 -30.3 -40%
98 106 -8.2 -8%
State project
4” mill depth
Made worse in many
cases
Cold Planing Still May Not
Improve Smoothness

31. If delamination occurs
the cut depth must be
deepened
Paving over a
delaminated surface
can result in deferential
compaction
A delaminated surface
will also provide a
rough reference line for
the paver
Delamination

32. Existing Pavement Surface
Aggregate Base/Subgrade
Cold In-place Recycling (CIR)
With Overlay as a Strategy
HMA Overlay Smoothness
Opportunity
CIR
Sort of a Smoothness
Opportunity

33. CIR as an Smoothness Opportunity:
 Regardless of the existing roadway’s
roughness, using best practices should result
in smoothness of the CIR at about 90 in/mi
MRI
 Using best practices, a 60 in/mi MRI should
then be attainable on the HMA overlay
 The Smoothness Subtask Group has made
the recommendation to raise the CIR
smoothness from 75 in/mi MRI and 180
in/mi ALR to 90 in/mi MRI and 240 in/mi
ALR, with no change to the overlay
smoothness requirements

34. Finally, Apparently Few Understood:
 How to correct the final paved surface for
smoothness
 What equipment must be used
 How to prepare effective grinding strategies
 The benefits and limitations of ProVAL
 The limitations as to the amount of corrections
that can be done by grinding

35. ProVAL Smoothness Assurance Model
(SAM)
Requires Experience
 Only models in two dimensions which may cause impacts
in other locations. Grinding wheels not necessarily on
same profile as grinding head when large variations in
transverse profile exist - May not be able to just correct a
single wheel path
 Must use the exact equipment modeled
 In some instances overestimates correction areas and
tends to be slower
 Corrects for ALR and not MRI

37. Start Distance (ft) Stop Distance (ft) Length (ft)
10.3 15.6 5.3
29.4 60.2 30.8
438.2 459.9 21.8
512.1 521.0 8.9
524.1 536.5 12.4
568.1 582.8 14.8
642.2 657.0 14.8
688.8 698.3 9.4
705.7 729.8 24.2
1953.3 1987.8 34.6
2004.9 2016.1 11.2
2024.3 2061.9 37.6
2064.7 2070.9 6.3
2071.1 2139.8 68.7
2168.3 2179.3 11.1
2201.7 2213.3 11.6
2217.8 2235.7 17.9
2236.3 2250.0 13.8
2260.3 2298.4 38.1
2341.3 2355.5 14.2
2364.0 2394.3 30.3
2417.8 2424.2 6.4
3375.7 3398.5 22.8
3407.0 3423.6 16.6
3427.5 3476.3 48.8
3510.5 3537.1 26.6
4347.8 4418.2 70.3
4452.4 4542.3 89.8
4573.3 4605.8 32.5
4881.1 4898.7 17.6
4899.1 4915.2 16.1
4917.4 4925.7 8.3
4957.3 4968.6 11.3
Proper locating with respect
to lengths and locations of
corrections is critical!
Correction equipment
operator’s transitions are
critical!
Correct a bump. Create two
more!
Corrections Take
Experience and Skill

38. But Grinding or Cold Planing Corrections
Can Only Do So Much
Can only go deeper or wider
Can’t fix a pavement or subgrade

39. WORKING CRACKS – Respond Dynamically to
Vehicles, Including Inertial Profiler
Working – Not correctible
by grinding
Non Working – Likely
correctible by grinding

40. The Good News:
 While it may be unreasonable to expect to obtain
smoothness with the design strategy specified,
there appears to be:
 Better understanding of the
issues involved by
Contractors and the State
 Better partnering to come to
an equitable solution before
construction begins

41. The Good News:
 There is effective dialog occurring in the Smoothness
Subtask Group – With a joint effort trying to resolve
issues
 Effective contractors have adapted and are raising the
bar
 The cry was – “It cannot be achieved”
 Now – “If the design strategy and existing roadway allows it,
we will get it”
 Many look forward to pay incentives that will likely be available
in the future (Late 2017 projects?)

42. The
public is
noticing

43. Thank You!
Questions?
dmatthews@pavementrecycling.com
(951) 934-4753