What is the Pavement Condition Index (PCI)?

The Pavement Condition Index (PCI) is a rating from 0 to 100 that shows the surface condition of a pavement. A value of 0 means a failed pavement and 100 means a new pavement. It comes from the type, severity and quantity of the distress that an inspector sees.

The PCI is a number for condition, so it has no physical unit. ASTM D5340 counts the error of an estimate in PCI points. The index is a tool for maintenance management. It gives an objective basis for maintenance needs and priorities. Repeated surveys show the rate of deterioration.

Which standard applies

ASTM D5340 covers airport pavements. ASTM D6433 covers roads and parking lots. The US Army Corps of Engineers developed the method for airfield pavements with funding from the US Air Force. The FAA and the US Naval Facilities Engineering Command later adopted it. The Corps also developed the road method, and the US Department of Defense and APWA adopted it. Both standards state that the PCI does not replace direct measurement of structural capacity, friction and ride or roughness.

ASTM D5340-24 and ASTM D6433-24 are the current editions. ASTM sells each standard, so a survey must follow the edition that the contract names. The US Department of Defense uses UFM 3-260-16 as its equivalent of ASTM D5340. The FAA publishes free PAVER distress manuals for asphalt and concrete airfields, and AC 150/5380-7B points to them.

The rating scale

The FAA scale in AC 150/5380-7B divides the range into seven categories. The FAA figure is an example. It also shows a custom scale of three categories, with boundaries at 70 and 55. The DoD manual UFM 3-260-03 gives the same seven ranges and these definitions:

The 1998 edition of ASTM D5340 uses the same boundaries with other names: Excellent, Very Good, Good, Fair, Poor, Very Poor and Failed. A value of 42.5 is Fair on that scale and Poor on the FAA scale. Always state which scale a report uses.

For roads, the agency typically sets the categories (NASEM 2024). AC 150/5320-6G says that PCI numbers give only a relative indication of surface condition. Treat the limits for maintenance, rehabilitation and reconstruction as relative, not exact.

How a survey works

The inspector divides the pavement into branches. Each runway, taxiway and apron is a separate branch. A branch has sections of uniform construction, maintenance, usage and condition. A section has sample units. For asphalt, a sample unit is 5,000 plus or minus 2,000 square feet (450 plus or minus 180 square meters). For concrete, it is 20 plus or minus 8 slabs.

The standard allows an inspection of all sample units, of enough units for a 95 percent confidence level, or of fewer. Inspecting all of them is usually too costly for routine management. It suits project analysis, where it helps to estimate maintenance quantities. The minimum number n of sample units for 95 percent confidence is:

n = N x s^2 / ((e^2 / 4) x (N - 1) + s^2)

N is the number of sample units in the section. The acceptable error e is commonly 5 PCI points. The standard deviation s between sample units is assumed to be 10 for asphalt and 15 for concrete at the first inspection. Later inspections use the value that the previous inspection measured. The inspector then spaces the units evenly through the section, with a random start. For other work, the standard gives an example of one agency that surveys fewer units. It surveys 1 unit when a section has 1 to 5 units, and 2 units for 6 to 10. It surveys 3 units for 11 to 15, 4 units for 16 to 40 and 10 percent above 40.

The inspector walks each sample unit and records the type, severity and quantity of every distress. The tools are a data sheet, a hand odometer wheel and a 12 in (300 mm) scale. For asphalt, the inspector also uses a 10 ft (3 m) straightedge or string line. The inspector works on a pavement with traffic and aircraft noise, so the standard requires coordination with airport operations staff. It also requires that hearing protection is available.

How the PCI is calculated

The calculation for an asphalt sample unit has these steps:

1. Add the quantity of each distress type at each severity level.
2. Divide each quantity by the area of the sample unit and multiply by 100. This is the percent density. For concrete, the density is the percent of slabs that have the distress.
3. Read the deduct value (DV) for each distress and severity from the deduct curves of the standard.
4. If none or only one deduct value is greater than 5, use the total deduct value as the maximum corrected deduct value (CDV). Otherwise, find the maximum CDV with the iterative procedure that follows.
5. Subtract the maximum CDV from 100.

PCI = 100 - maximum CDV

The iterative procedure first limits the number of deduct values to m. The standard gives m as m = 1 + (9 / 95) x (100 - HDV). HDV is the highest individual deduct value. The value of m is at most 10. Keep the m largest deduct values. Multiply the last one by the fractional part of m. Then repeat these steps:

1. Sum the deduct values and count q, the number of deduct values greater than 5.
2. Read the CDV from the correction curve for q and the sum.
3. Reduce the smallest deduct value that is greater than 5 to 5, and repeat until q is 1.
4. The maximum CDV is the largest CDV from all the passes.

The standard gives a worked example for an asphalt sample unit. The deduct values are 27.0, 21.0, 20.0, 9.0, 4.9, 4.8, 4.0 and 2.0. The highest is 27.0, so m = 1 + (9 / 95) x (100 - 27) = 7.92. The seven largest values stay, and the eighth becomes 2.0 x 0.92 = 1.8. The passes give these results:

The maximum CDV is 57.5, so the PCI of the sample unit is 100 - 57.5 = 42.5. The CDV does not rise steadily from pass to pass, so the standard takes the largest value.

The PCI of a section is the average of the PCI of its sample units. This applies when the inspector surveys every unit or selects all of them at random. Sample units that hold an unusual distress, such as a utility cut, are “additional” units. If the inspector surveys any, the section PCI is a weighted average.

Distress types

The inspector records only the distress types that the standard defines. The 1998 edition of ASTM D5340 lists 16 asphalt types:

• alligator cracking, bleeding, block cracking, corrugation and depression
• jet blast erosion, joint reflection cracking, and longitudinal and transverse cracking
• oil spillage, patching, polished aggregate, and raveling and weathering
• rutting, shoving, slippage cracking and swell

It lists 15 types for jointed concrete pavement:

• blowup, corner break, longitudinal, transverse and diagonal cracks, and durability cracking
• joint seal damage, small and large patching, popouts, and pumping
• scaling, map cracking and crazing, settlement or faulting, shattered slab, and shrinkage cracks
• joint spalling and corner spalling

The 2009 PAVER distress manuals define 17 asphalt types and 16 concrete types. They list weathering and raveling as two distresses, and they add alkali-silica reaction for concrete. The current standard may differ again, so use the edition that the survey contract names.

What the PCI does not measure

The PCI uses the distress that is visible on the surface. ASTM D5340 states that it cannot measure structural capacity and gives no direct measure of skid resistance or roughness. The FAA assesses roughness to AC 150/5380-9 and friction to AC 150/5320-12. A DoD manual adds that a surface can rate Good and still have underlying conditions that fail under repeated aircraft operations.

The PCI is not the PCR. The PCR is the Pavement Classification Rating, which reports the load-carrying capacity of a pavement.

The PCI is not the PSI. The Present Serviceability Index is a 0 to 5 rating of ride quality from the AASHO road test of the late 1950s. The FHWA notes that it is falling out of use. The PCI and the International Roughness Index are also different. The IRI comes from a measured profile, and the PCI comes from distress that an inspector records.

The standard sets limits for the accuracy of the distress measurements. When the inspector measures a distress again, linear measurements should agree within 10 percent and area measurements within 20 percent. The inspector should identify distress types correctly 95 percent of the time. The 1998 edition gives no precision statement from statistically designed tests.

Use in airfield management

A pavement management program uses the PCI to track condition, model the deterioration and schedule maintenance. PAVER and FAA PAVEAIR are programs that do this. The software reports in AC 150/5380-7B work with minimum acceptable condition levels that the user sets. A report predicts the year in which a section reaches the minimum PCI, and it estimates the cost.

The AC gives no single PCI value that triggers maintenance, and it leaves the levels to the airport. The DoD manual describes a critical PCI. Below it, local maintenance is no longer cost-effective, and major rehabilitation starts. Each Service sets its own levels. The manual also reduces the allowable gross load by 25 percent when the PCI is 40 or lower.

A federally obligated airport must make a detailed inspection at least once a year. A PCI survey to ASTM D5340 allows the interval between detailed PCI surveys to be three years. Routine maintenance inspections continue in addition.

Drones

A drone can capture the images for a visual survey. A PCI from drone images follows ASTM D5340 only if the survey meets the procedure of the standard. TarmacView surveys airfield pavement by drone, rates the distresses to ASTM D5340 and computes a PCI for each sample unit. The service is offered as early access.