Traffic Surveys
How to Conduct a Classified Traffic Count
A practical framework for planning a classified count.
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
A classified traffic count begins with a written class dictionary, count location, time periods, interval structure and review rule.
Define the classes
State each category and its decision rule before observation. Body-type and axle-based categories should not be mixed without explaining the distinction.
Set the count structure
Name the count line or junction matrix, directions, intervals and any pedestrian or cycle treatment. Apply the same structure at every included site.
Validate totals
Check that class totals reconcile with all-vehicle totals and re-review ambiguous or high-volume periods against the source.
Frequently asked questions
Can classes be client-defined?
Yes. The approved class scheme is the reference for observation and delivery.
What happens when a vehicle cannot be classified?
Use the documented unknown or exception rule; do not guess.
Go deeper
Vehicle Classification Methodology
How a project-specific vehicle class scheme is defined and applied consistently.
View Methodology →Related services