Outline

On this page:

  • Objective
  • Methodology
    • Manual Distress Evaluation
    • Pavement Condition Index (PCI)
      • Calculation of PCI
      • Project Notes on PCI
    • Maintenance and Rehabilitation
  • Recommendations
  • Conclusions

Objective

  •  Prioritize maintenance of flexible pavement sections in the Smart Road. 
  • Once condition prioritization is complete, recommendations for maintenance activities will be included. 
  • The condition of the sections will be determined using a Pavement Condition Index (PCI), which is derived from identifying flexible pavement distresses. 

Methodology

  • Manual Distress Evaluation:Identify Distresses in photos and determine severity and size
  • Use distresses in coordination with ASTM D6433-07 to calculate the Pavement Condition Index using the Deduct Value Method
  • Use PCI to prioritize maintenance of the sections
  • Make M&R Recommendations based on PCI and VDOT M&R Activities

Manual Distress Evaluation

  • Identify Distresses in Photos
    • Distress Severity
    • Distress Size
      • Fatigue Cracking: Area (ft^2)
      • Longitudinal/Transverse Cracking: Length (ft)

Assumptions

  • Longitudinal cracking along joint (lane-shoulder interface) was disregarded
    • Result of construction when multiple passes were taken and the joint was not properly sealed.
  • Fatigue Cracking: may actually be extra asphalt from the construction process
    • Asphalt tracked on the paver tires and across the new pavement
    • This assumption may lead in a lower PCI than expected for some of the sections, as fatigue cracking has high deduct values.
  • Only the right-side lane was analyzed for distresses
    • Photos were directed at the right-hand lane and distress quantities and severities would be difficult to determine for the left-hand

Pavement Condition Index (PCI)

PCI

  • General indication of the pavement’s surface condition
  • Ratings from 0-100 to describe pavement condition, with 100 being the best condition and 0 being a failed pavement. 
  • A pavement will start at a PCI of 100 and have points deducted based on the distresses
  • The closer the PCI is to 0, the more immediate and severe reconstruction and replacement must take place.  
  • The structural condition refers to the pavement’s ability to carry traffic.  A distress that causes structural damage can impair a road’s ability to support traffic.
  • Functional condition refers to the ride quality and safety of a pavement; a functional distress causes surface issues that affect the ride quality.

 

M&R Associations with PCI

  • Pavements with “Excellent” to “Good” PCI usually require some type of preventative maintenance, such as crack seal, slurry seal, or thin overlay. 
  • A PCI of “Fair” indicates that the pavement will need minor rehabilitation, such as overlay or mill and overlay. 
  • Pavements with “Poor” to “Very Poor” PCI ratings need major rehabilitation. 
  • While the ratings determined from visible distresses represent the pavement’s overall condition, more investigation must be done for project-level decision making. This includes knowing the pavement’s maintenance history, making field visits, and performing other investigations as necessary. 

The distresses used in PCI calculations are the observed surface distresses of the pavement, so PCI provides a general idea as to the condition of the surface of the pavement and may not identify underlying structural issues. 

Calculation of PCI

  •  ASTM D6433-07 was used to calculate PCI (Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys) 
    • Deduct Value Method: PCI starts at 100 and the distresses are combined to form a Corrected Deduct Values (CDV) that is subtracted from the PCI of 100.  
    • Each distress category (Fatigue Cracking, Longitudinal/Transverse Cracking) is a sum of all of the distress areas or lengths and is divided by the total pavement (12ft wide * length) to determine the % density of the distresses in the section
    • Further followed ASTM standard to calculate the Corrected Deduct Value (CDV) that combines ALL distress Deduct Values (DVs)

Project Notes on PCI

  • The only distresses present in the Smart Road flexible sections were fatigue, longitudinal, and transverse cracking.  ASTM D 6433-07 ranks distress severities as Low (L), Medium (M), and High (H), where distress of High severity have higher deduct values than those of a Low severity.
  • Pavements with very few distresses and distresses of low severity are likely to have a PCI of “Excellent” to “Good," although still in good condition  usually require some type of preventative maintenance, such as crack seal, slurry seal, or thin overlay.  Those in poorer condition (lower PCI) will have more intensive M&R activities, such as Corrective Maintenance (CM) or Rehabilitation.


  • Section E’s lower PCI may be attributed to the fatigue cracking identified in the photos
    • Fatigue cracking contributed a deduct value of 21
    • Fatigue cracking near the bridge
      • Likely caused by improper pavement compaction abutting the bridge. This is a common problem for the interface between the bridge and the pavement
  • Although Sections F and G have PCI of 100, meaning that they are in “Excellent” condition and therefore do not require maintenance (DN), it is recommended that some preventative maintenance be applied to the section.  This maintenance should be scheduled after the maintenance on the more deteriorated sections has been completed.  
    • Aged asphalt

PCI by Section on The Smart Road

Maintenance and Rehabilitation (M&R)

  • DN = Do Nothing
  • PM = Preventative Maintenance
    • Expected Life: 2-5 years
      • Minor Patching (<5% of Pavement Area: Surface Patching: Depth 2 in)
      • Crack Sealing
      • Surface Treatment (Chip Seal, Slurry Seal, Latex, ‘Macro Texture,’ ‘Novachip,’ etc.
  • CM = Corrective Maintenance
    • Expected Life: 7-10 years
      • Moderate Patching (<10% of pavement area: Partial Depth Patching: Depth 6 in) 
      • Partial Depth Patching (<10% of Pavement Area: Depth 4-6 in) and Surface Treatment
      • Partial Depth Patching (<10% of Pavement Area: Depth 4-6 in) and Thin ( < 2 in) AC Overlay
      • < 2 in Milling and < 2 in AC Overlay
  • RM = Restorative Maintenance --> heavy patching, full-depth patching, mill and overlay
  • RC = Reconstruction


Section E

  • Only 3 points below the PM range
  • Treated with CM activities, such as:  moderate or partial-depth Patching, followed by a surface treatment or thin overlay.
  • The Preventative Maintenance actions that will treat the fatigue cracking, if severe, include: improving the structural capacity, such as an overlay, and/or complete reconstruction of the section

Section C

  • DN is an M&R option for Section C, although PM is recommended

  • Including minor patching, surface treatment, or crack seal.
  • Crack seal would keep moisture out of the transverse and longitudinal cracks in the pavement and help to slow further deterioration due to the cracks.  
  • Primary deduct value for the PCI of Section C was fatigue cracking, with a value of 18 (See Appendix A). 
    • Because the primary distresses are fatigue cracking, CM may be recommended in order to solve the fatigue cracking, as surface cracking may not solve the root problem of the fatigue cracking. 
    • If the fatigue cracking is not bottom-up cracking, the partial-depth patching can completely correct the distress.  The surface treatment or thin overlay will protect the pavement from additional aging and oxidation from weathering, as well as cover the longitudinal and transverse cracks to prevent moisture infiltration.

Sections A & B

  • Similar PCI values, 84 (A) and 86 (B)

  • Section A has slightly more fatigue cracking than section B (deduct value of 11 and 5, respectively). 

  • Because fatigue cracking may be present, it is recommended that PM be performed if budget allows, although with the calculated PCI, DN is also an option

  • Minor patching, crack sealing, or surface treatments are considered forms of PM. 

    • Minor patching may be necessary to correct the fatigue cracking in Section A, as it is more frequent than in section B.
    • Surface treatments or crack seal should be adequate for Section B

Section J  

  • PCI of 89, is right on the lower range of DN.  The next range down, for a PCI of 79-88, is DN or PM. 
  • Therefore, it is likely that Section J would fall under the DN M&R category. 
  • Sections E, C, A, and B should have priority over Section J for maintenance as their PCI values are lower,
  • Further Investigation: PCI value may be inaccurate due to the lack of data (2 photos available; most other sections had 10-14 photos). 
  • If further investigation is performed and the PCI remains the same, PM is recommended for Section J to prevent further deterioration, especially given the pavement age (although priority is on sections with worst PCI first).  

Section D

  • PCI of 98, is also very close to being in “Excellent” condition, DN

  • PM is still recommended due to the pavement’s age.

Sections H&I

  • PCI values of 91 (H) and 94 (I), in good condition, DN
  • Again, PM is recommended if funds allow, due to the pavement age. 
  • Priority between H and I: Section H should receive attention before Section I, as it has fatigue cracking (deduct value of 5) and longitudinal/transverse cracking (deduct value of 5).  Section I has deduct values of 5 and 0 for fatigue cracking and longitudinal/transverse cracking, respectively. 
    • Therefore, maintenance activities performed on Section I should be focused more on the fatigue cracking and less on the transverse/longitudinal cracking.

Sections F & G

  • PCI of 100, meaning that they are in “Excellent” condition and DN M&R 

  • Still recommend PM

  • Maintenance should be scheduled after the maintenance on the more deteriorated sections has been completed. 
  • Potential maintenance activities for Sections F and G include a surface treatment or crack seal. 
    • Because of the limited surface distresses, crack seal may be an effective preventative maintenance treatment to slow deterioration resulting from the cracks.  To protect the aging binder, a surface treatment may also be an appropriate preventative maintenance action.


Recommendations

The provided data photos of the road are directed from the driver’s view and photos are not directly looking down on the pavement.

Because the view is not looking directly downward on the distresses, they may be incorrectly identified and/or quantified.

In addition, the entire area of the distress may not be visible, and therefore not accounted for.  Because of this, the distress observations performed by the group may not be completely accurate.  The group worked with the data that was available 

Recommendations for future manual pavement evaluation (or even automated pavement distress identification):

  • Photos to aim downward so that areas are not skewed and distresses are visible.  
  • More recent photos, as the data received was from 2008. 
  • If time, availability, and weather conditions permitted, a walk along the test sections would be recommended to verify distresses that were identified in the photos, including their severity and the area they cover. 

Conclusions

  •  Sections in the “Do Nothing” range (100-89) include D, F, G, H, I, and J (PCI: 98, 100, 100, 91, 94, and 89, respectively). 
  • Sections in the “Do Nothing” or “Preventative Maintenance” range (88-79) are: A, B, and C (84, 86, and 80, respectively). 
  • The section in the worst condition, Section E, is below the “Preventative Maintenance” threshold, but above the “Corrective Maintenance” threshold, although Corrective Maintenance is recommended to treat the fatigue cracking.  
  • Overall, the Smart Road is in good condition and only requires minor M&R activities, as most of the deterioration is likely due to aging of the materials.  

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