Cracking is the earliest and most consequential warning sign of pavement deterioration. For decades, agencies relied on manual distress surveys to count and categorize cracks. ASTM E3303 was introduced to standardize how automated collection systems translate high-resolution 3D data into repeatable and defensible numbers.
How PSCM and PSCI are calculated
Traditional ASTM D6433 PCI inspections require an inspector to classify whether a crack is fatigue, longitudinal, or block cracking before calculating deduct values. In contrast, ASTM E3303 evaluates cracking based strictly on physical geometry: crack length, width, and surface area.
1. Calculating PSCM (The Physical Metric)
The roadway is divided into analysis intervals and discrete “analysis tiles” (typically 2-meter sub-sections or individual slab lengths). For each tile, automated sensors and algorithms identify crack paths and measure their apertures per the ASTM E3303 standard that yields the actual percentage of the pavement surface compromised by crack openings. The segment PSCM is then computed as the weighted average across all tiles.
2. Converting to PSCI (The Index Score)
Because public works professionals are accustomed to 0–100 condition scales (similar to PCI), the standard provides conversions of PSCM into PSCI using an exponential decay curve.
What the score ranges mean
While PSCM gives pavement engineers exact geometric aperture data, the PSCI score can provide familiar treatment thresholds for municipal asset management. The following are example condition category ranges that could be used in pavement management decision-making frameworks:
- 85–100 — Excellent / Good: Minor or hairline cracking. Preventive treatments such as crack sealing or surface sealing prevent moisture intrusion at minimal cost.
- 70–84 — Satisfactory: Noticeable longitudinal or transverse cracks. Slurry seals, micro-surfacing, or chip seals preserve surface integrity.
- 55–69 — Fair: Structural cracks are expanding into wheel paths. This is the critical tipping point: a thin asphalt overlay or mill-and-fill arrests structural failure before costs multiply.
- 40–54 — Poor: Extensive pattern or fatigue cracking. Requires structural rehabilitation (deep milling, intermediate binder course, or structural overlay).
- 0–39 — Failed / Reconstruction: Widespread interconnected cracking and base failure. The surface cannot be preserved; full-depth reclamation (FDR) or complete reconstruction is required.
How PSCI differs from traditional PCI
While both report on a 0 to 100 scale, they answer different engineering questions:
| Attribute | Pavement Condition Index (PCI) | Pavement Surface Cracking Index (PSCI) |
|---|---|---|
| Governing standard | ASTM D6433 | ASTM E3303 |
| Distress scope | Multi-distress (cracking, rutting, potholes, weathering, bumps) | Dedicated solely to cracking (aperture, density, extent) |
| Data collection | Manual walking surveys, windshield surveys, 3D laser profilers or AI dashcams | Automated high-speed 3D laser profilers (e.g., LCMS) |
Network PSCI vs. tile-level PSCM
Reporting an average PSCI across an entire arterial corridor is helpful for council presentations, but it can mask localized failures.
An average segment PSCI of 75 may look acceptable on paper, but if the underlying tile-level PSCM shows that the cracking is concentrated entirely within the outer wheel paths, moisture is penetrating the base course where heavy axle loads occur. Pair your high-level PSCI network summaries with localized tile distributions to catch fatigue zones before they blow out into potholes.
The mistake to avoid
The most common trap is treating PSCI as an identical substitute for overall PCI.
A road segment can have virtually no surface cracking, yet suffer from severe rutting, poor friction, or ride-quality issues (high IRI). Conversely, a street with tight, superficial thermal cracks might receive a low PSCI despite a structurally solid base.
The best approach: Use PSCM/PSCI as an automated, objective input into your broader Pavement Management System (PMS). Let PSCI trigger preventive seal schedules, while combining it with rut depth, roughness (IRI), and structural capacity to determine multi-year capital rehabilitation budgets.
With features like Super Segments, AtlasView can retain granular cracking metrics while grouping contiguous blocks into unified corridors, letting you make practical maintenance decisions without losing condition details.
Frequently asked questions
- What causes a low PSCI score?
- PSCI decreases as the total area of open cracks increases. Both crack density (frequent cracks) and crack aperture (wide cracks) drive up the PSCM, which rapidly pulls down the 0–100 PSCI score.
- Can PSCI be gathered from manual visual inspections?
- No. ASTM E3303 requires repeatable millimeter-level precision for crack width and length across longitudinal and transverse intervals. It is designed specifically for automated survey vehicles equipped with 3D laser sensors, line projectors, and high-resolution imaging systems.
- Does PSCI identify fatigue versus thermal cracking?
- Not by default. ASTM E3303 is an objective physical measurement of surface openness rather than distress causation. However, advanced asset management platforms use the location of the cracks across transverse road zones (such as wheel paths vs. centerlines) to automatically infer fatigue, block, or longitudinal causes.