Pavement Thickness — Simplified (AASHTO/CBR Method) implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t7-121

Effect

Computation or source lookup only

Input and validation requirements

The specification has multiple failure points: CBR = 0 produces an undefined division, the required fit constant A and logarithm base are unspecified, and no selector or applicability rule distinguishes the CBR thickness formula from the AASHTO structural-number branch.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "method": "CBR_empirical_fit",
    "CBR": 5,
    "design_ESALs": 1000000,
    "A": 100,
    "A_units": "mm",
    "log_base": 10
  },
  "expected_outputs": {
    "estimated_pavement_thickness_mm": 268.328157
  },
  "reference_data": {
    "calibration_row": {
      "A": 100,
      "units": "mm per [log10(ESAL)/sqrt(CBR)]",
      "source_convention": "Illustrative user-specified calibration; no universal AASHTO table value"
    },
    "logarithm": {
      "base": 10,
      "source_convention": "Widely tabulated standard mathematical convention for common-log pavement curve fits"
    }
  },
  "working": "t = A·log10(ESAL)/sqrt(CBR)\nlog10(1,000,000) = 6\nsqrt(5) = 2.2360679775\nA·log10(ESAL) = 100·6 = 600 mm\n t = 600/2.2360679775 = 268.328157 mm"
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json