ORIGINAL: Incentive Decentive

1
ORIGINAL Incentive / Decentive
Road Profile Users Group October 23, 2001, Lake
Tahoe, Nevada
NEW Federal Lands Highways Road Profile
Specifications

• Roger Surdahl, P.E.
• FHWA Technology Coordinator
• Central Federal Lands Highway Division
• Denver, Colorado

2
Pavement QualityAcceptance Parameters

• Asphalt Content
• Aggregate Gradation
• Density
• Pavement Smoothness

3
Pavement Smoothness

• Applies Only to the Final Surface
• Pavement Smoothness Types I, II, III, and IV
• Profile Index mm/km
• Type Upper Spec Limit Defective Limit
• I 80 160
• II 125 190
• III 160 240
• IV Straightedge, 6 mm (max) in 3 m

4
FHWAs StatisticalAcceptance Specification

• Specification Target Values or Limits
• Measured Average and Standard Deviation
• Quality Index, Qu (USL - Avg) / Sd
• Percent of Work Outside Specifications
• Pay Factors
• 105 Maximum Incentive (0 defective)
• 75 Maximum Disincentive (40 defective)
• lt75 Remove and Replace

5
Example Calculation
Type III Roadway 5 km in length USL 160
mm/km 50 segments of 1/10th km each One
bridge, exclude that segment For the 49
Remaining Segments Final PRI Average 130
mm/km Final Standard Deviation 20 mm/km Qu
(USL - Avg) / Sd gtgtgt (160 130) / 20
1.50 Percent Outside Specifications
6 Therefore, Pay Factor 102
6
FHWA Smoothness Study - Measured over 220
projects at 0.2 blanking band - Found that 95
of all contractors could improve smoothness by ½
for each 1-1/2 inch overlay
7
0.0 BB Smoothness

• Found the 0.2 blanking band data was not
  normally distributed
• Re-measured 21 projects at 0.0 blanking band
• Developed a statistical correlation shift of a
  PRI average of 14 points

8
Correlation Equations for the 0.2 and 0.0
Blanking Bands

• Profile Ride Index
• 0.0 PRI BB 14.1043 1.0832(0.2 PRI BB)
• R2 0.85
• Standard Deviation
• 0.0 SD BB 1.06186 1.12765(0.2 Sd BB)
• R2 0.92

9
New Pavement Smoothness Specification

• Three Roadway Types
• I New (310 mm/km)
• II Overlays
• III Excluded Areas
• Based on 0.0 blanking band
• Statistical acceptance methods still apply

10
Type II Overlay Smoothness

• Still uses California
• type Profilograph
• Contractor measures
• existing PRI (310 min)
• and STD to calculate
• USL based on one or
• two lifts
• USL C Sd
• Where
• USL is Upper Spec Limit
• C is a Smoothness Constant
• Sd is Standard Deviation
• Contractor measures final PRI to calculate Pay
  Factor

11
Table 401-3 (excerpt)Overlay and Recycle
Smoothness Constants(C) and Standard
Deviation(Sd) for Determining Upper Specification
Limits(USLx)
12
Example Calculation
Type II Roadway 5 km in length Two lifts of
asphalt required 50 segments of 1/10th km
each Minimum PRI 310 mm/km One bridge, exclude
that segment For the 49 Remaining
Segments Existing PRI Average 290 mm/km, Use
310 mm/km Existing Standard Deviation 20
mm/km USL C2 Sd2 gtgtgt 108.9 104.2 213.1
mm/km After paving two lifts, for the 49
Remaining Segments Final Average 185
mm/km Final Standard Deviation 15 mm/km
Qu (USL - Avg) / Sd gtgtgt (213.1 185) / 15
1.87 Percent Outside Specifications
2 Therefore, Pay Factor 105
13
Conclusion

• FLH will continue to refine the specification as
  more data are generated
• Implementation in 2003
• The focus is still on smooth roadways
• More uniform application of acceptance criteria
  and farer sharing of the risks