WEBVTT

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Every chainage in this example is numeric,

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but the sequence is one, two, one

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point five, then two point five kilometres.

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The pattern changes direction twice within one

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survey group. File order is not the

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same as the direction a vehicle travelled.

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A consistently descending survey can be legitimate.

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A lower number by itself is not

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proof that a vehicle went backwards. The

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cross-row check groups records by road, lane

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and measurement date where available. It examines

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changes in start-kilometre progression within that group,

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rather than mixing unrelated roads. The current

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ordering rule flags repeated direction changes: two

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or more reversals. It tolerates one reversal.

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This is a diagnostic for potentially mixed

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or scrambled records, not a blanket demand

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to sort every file. Project alignment can

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also compare chainage with geometric position where

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suitable reference data exists. Keep that spatial

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evidence separate from the row-order diagnostic. Review

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original run boundaries, lane attribution and acquisition

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records before changing data. The current direction

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analysis does not establish time-of-day travel direction.

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Resolve the cause and retain the evidence.