Turning Movement Count Methodology

Definition and purpose

A turning movement count (TMC) assigns each observed road user to a defined approach, movement and reporting interval. The matrix is agreed before observation so totals can be checked and used without reconstructing the survey rules.

Use it when a design, operations or planning decision depends on how demand is distributed through an intersection.

Required inputs

• Junction plan or unambiguous location reference
• Approach and movement matrix
• Observation dates, periods and intervals
• Vehicle and active-travel class scheme
• Required spreadsheet or report format

Video and camera considerations

For video-based work, each approach, stop line and crossing that matters to the scope should be visible. Camera placement must allow movements to be distinguished without relying on guesswork.

Observation, classification and intervals

Observation process

Confirm the junction arms, direction labels and movement rules. Record every agreed approach and allocate each movement to the approved matrix for each interval.

Movement and classification process

Apply the project class dictionary while recording the movement. If a road user cannot be classified confidently from the available source, follow the agreed exception rule rather than inventing a category.

Time intervals

Fifteen-minute intervals are often useful where peak variation matters; the reporting interval is selected by the brief, not assumed.

Validation and QA/QC

Reconcile approach totals with the movement matrix, check all requested periods are present, and review unusual peaks against the source material and documented exceptions.

Common problems and limitations

• An obscured stop line can make turning intent unclear.
• A camera aimed too tightly may omit a slip lane or crossing.
• Unclear movement labels create inconsistent coding across locations.

The count describes the observed period and defined movements. It does not by itself establish capacity, future demand or design compliance.

Typical deliverables

• Approach-by-movement interval tables
• Classified totals where requested
• Study notes and defined assumptions
• Quality-review record or exception notes

Illustrative output format

Illustrative sample data only — not a project result or benchmark.

Frequently asked questions