Traffic Surveys
How Long Should a Traffic Count Run?
Choosing periods that answer the project question.
By SWAT Alliance Editorial Team · Updated 25 August 2026
Insight at a glance
A short visual checklist for better study decisions.
Use the article as a starting point, then confirm the project-specific scope, method, review and output with the delivery team.
Question
What decision should this evidence help someone make?
Scope
Which locations, movements, classes and periods matter?
Review
How will completeness and definitions be checked?
Output
What format will make the result easiest to use?
Short answer
Traffic-count duration should be long enough to answer the stated project question and reflect the relevant operating periods, while remaining honest about what was observed.
Match duration to purpose
A peak-period junction count, a corridor profile and an automatic monitoring study answer different questions and need different windows.
Consider variation
Day type, events, school terms, weather, construction and unusual incidents can affect whether a period is representative of the decision.
State the boundary
Report dates, start/end times, intervals and any excluded or abnormal periods so the result is not mistaken for a universal average.
Frequently asked questions
Is a 24-hour count always necessary?
No. It depends on the decision and required temporal coverage.
Can a short video be useful?
Yes, when it clearly covers the agreed periods and the scope does not claim more than it observes.
Go deeper
Traffic Data Validation & Quality Control Methodology
A documented review framework for traffic data before it is delivered or relied upon.
View Methodology →Related services