Survey quality
IRI in South Africa: what the number tells you—and what to check next
Follow quarter-car equations, suspension travel and amplitude sensitivity, then interpret roughness with section and measurement-quality evidence.
11 min readRoadSense field notes
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MADE VISIBLE.
Explore how road measurements become evidence. Clear explanations, interactive examples and sources you can follow.
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18 insights
Survey quality
TMH9 visual assessment: keep degree, extent and evidence together
Calculate coverage from unique affected intervals, test boundary sensitivity and keep TMH9 degree, extent and spatial evidence distinct.
9 min readPavement evaluation
FWD deflection bowls: read the shape before choosing a treatment
Follow the FWD load pulse, calculated deflection and stress fields, then test stiffness sensitivity and interpret measured bowl evidence.
12 min readSurvey quality
What belongs in a road-condition survey acceptance pack?
Reconcile received, checked and accepted survey records with worked set accounting, denominator sensitivity and traceable acceptance evidence.
8 min readEngineering workflows
Chainage, direction and wheelpath: reconciling survey records
Work through direction reversal, coordinate error propagation and round-trip checks before comparing route and wheelpath measurements.
8 min readPavement evaluation
Uniform pavement sections: a defensible starting point for investigation
Calculate section means and residual error across candidate boundaries, then test whether the statistical split has engineering support.
8 min readAsset management
VCI mathematics: from defect ratings to a reproducible index
Work through degree, extent, weighting, normalisation and the nonlinear VCI transformation, then test sensitivity to an input rating.
8 min readPavement evaluation
Network screening and project investigation answer different questions
Calculate conditional screening rates, reconcile nested populations and distinguish programme selection from diagnostic accuracy.
10 min readPavement evaluation
TRH12 rehabilitation investigation: build the evidence before the design
Explore model residuals, stiffness sensitivity and load–modulus ambiguity within a traceable rehabilitation investigation.
9 min readDesign methods
DCP and DSN800: definitions, calculations and applicability
Calculate incremental DCP penetration rates, compare weighted summaries and identify the evidence needed before using a DSN800 correlation.
8 min readDesign methods
How layered-elastic response enters pavement design
Derive circular-load vertical stress, test depth sensitivity and use a homogeneous benchmark before interpreting layered pavement analysis.
8 min readDesign methods
Pavement Number: questions to ask before applying the method
Trace thickness conversions and layer-stack errors, then define the equation and applicability checks required for a Pavement Number result.
7 min readDesign methods
Traffic growth and E80s: show the assumptions behind design traffic
Derive cumulative traffic growth, test year numbering and zero-growth limits, and separate forecast quantities from E80 equivalency assumptions.
7 min readPavement evaluation
Drainage evidence in a pavement investigation
Derive a reservoir water balance, plot storage and discharge, and test outlet sensitivity without confusing the model with field seepage.
7 min readAsset management
Upgrading an unpaved road: organise the decision evidence
Calculate in-place material loss, test thickness sensitivity and distinguish volume evidence from an unpaved-road upgrading decision.
7 min readAsset management
Lifecycle cost comparisons: make scenarios reproducible
Work through dated cash flows, discount-rate sensitivity and consistent comparison assumptions for pavement lifecycle cost scenarios.
7 min readSurvey quality
Repeatability, bias and uncertainty in road measurements
Calculate sample scatter and uncertainty of the mean, then test sample size and show why shared bias survives tight repeatability.
8 min readEngineering workflows
Engineering charts that preserve units, provenance and uncertainty
Calculate chart coordinates, compare axis ranges and expose visual amplification while retaining engineering units, data and provenance.
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