Flagger training and certification requirements

From Colorado Department of Transportation (CDOT) Flagger FAQs website:
“In order to obtain or renew your Colorado Flagger certification, you must fulfill the following requirements:

1. Be 18 years of age or older,
2. Be trained by an CDOT authorized entity, and
3. Pass a closed book examination.”

See CDOT Authorized Flagger Training Entities.