PAVEMENT CONDITION INDICES

n Historic development of pavement condition indices n The basic functions of condition indices in PMS n Different types of condition indices n Development of a pavement condition index Instructional Objectives

Condition Surveys Ride Quality, Surface Distress, Rutting Pavement Indices Pavement Wheel Path ProfileRide Quality Index IRI Pavement Surface DistressesSurface Distress Index RuttingAverage Pavement Rut Depth Structural Capacity Deflections Structural Capacity Index Converts collected data to single value (over the pavement section)

Need for Condition Surveys Ride Quality Index  Measure Pavement Wheel Path Profile(s) to assess Pavement Ride Quality  Convert Pavement Wheel Path Profile (L&R) to Pavement Ride Quality Indices (IRI) 0.1 mile IRI

n Trigger treatments n Calculating life-cycle costs n Evaluate network conditions n Compare roads with different distresses Need for Pavement Distress Indices

n Transform pavement condition data into pavement condition indices n Deduct values developed for various levels of distress severity and extent n Two basic approaches - Expert opinion - Engineering criteria Pavement Condition Indices Development

Present Serviceability Rating Based on Verbal Description of Distresses and Ride Quality

PSI = 5.02-log(1+SV)-1.38(RD) (C+P) 1/2 Where: PSI = Statistical estimate of the Mean PSR SV = Slope variance (roughness) RD = Rut Depth C = Cracking(ft 2 / 1000 ft 2 ) P = Patching (ft 2 / 1000 ft 2 ) Present Serviceability Index

Computed using a very simple deduct based formula: n PCI = PCI max - ΣDeduct Value n Example = 60 Pavement Condition Indices Development

Deduct Value Table From Expert Opinion

Deduct Value Graph From Expert Opinion

n Scales used for condition index n Scales chosen to meet agency needs and perceptions n Typical scales are 0-100, 0-10, 0-5 Engineering Criteria Approach: Index Scale

n Index value representing unacceptable pavement condition n Typically taken as middle of an index scale, such as 50 (0-100 scale) or 2.5 (0-5 scale) n May be set to represent a range such as 40 to 60 (0-100 scale) or 2 to 3 (0-5 scale) Engineering Criteria Approach: Threshold/Trigger Value

n Pavement distress level (severity, extent), considered unacceptable n Amount of distress for each severity level where action should be taken to correct distress n May be numerically different for various types of distress Engineering Criteria Approach: Engineering Criteria

n Use a 100 to 0 Scale n Set Threshold/Trigger Condition Value at 50 n Set Engineering Criteria 90% Low Severity Cracking 25% Medium Severity Cracking 15% High Severity Cracking Engineering Criteria Example

n Develop Plot of Deduct Values - All three severities start at 0 and pass through the threshold value of 50 at the engineering criteria selected - In this example they pass through the threshold value of 50 at 15%, 25%, and 90% for low, medium and high severity cracking Engineering Criteria Example

Development of Deduct Values

n Develop Final Deduct Values from relationships shown on plot n The Deduct Values may be developed as set of continuous functions which may be shown:  as a plot of a chart  as a formula  as a set of deduct tables Engineering Criteria Example

Example Deduct Value Table (Straight Line approach)

Pavement Deduct Values ASTM D5340 “Paver” “Based on Engineering Experience”

Pavement Deduct Values Using Log-Log Chart

n Distress info - most variation - field procedure - distress definitions n Little opportunity to exchange information n Approximately. 80% of agencies use - distress index - serviceability index/rating - priority rating n No evident trends in development n 67% use composite indices Current Practices

NJDOT Practice Pavement Roughness Index – IRI Pavement Distress Indices –Non-Load Associated Distress Index (NDI) –Load Associated Distress Index (LDI) –Surface Distress Index Modified (SDIm)

NJDOT Practice 0.1 mile (528 ft) pavement section iNWP a WP L NWP b WP R NWP c ft ft

NJDOT Practice 0.1 mile (528 ft) pavement section 12 ft 1,75 ft2.5 ft 3.5 ft1,75 ft Wheelpath

NJDOT Practice NDI Distress Weights RCNDI Patching100 Shoulder Condition10 Cracks100 Long Jt Cond145 Trans Jt Cond145 Total500 BC/CONDI Patching60 Shoulder Condition10 Longitudinal Cracks140 Multiple Cracks150 Transverse Cracks140 Total500

DistressDistress Weights LMC300 Rut200 NJDOT Practice LDI Distress Weights

NJDOT Practice Distress Severity-Extent Weights

Rut Depth Weight

NJDOT Practice Surface Distress Indices SDIm = 0.8 NDI LDI LDI =

Questions?