Traffic guards, also known as traffic controllers, traffic marshalls/traffic marshals or flaggers, are trained to set up warning signs and barricades to slow down the speed of traffic in a temporary traffic control zone. When they are on scene they will set up equipment to warn approaching traffic about the incident.

Traffic guards use a variety of equipment:

In some cases, alternatives to human traffic guards are used for traffic control. Traffic guards may be assisted by Automated flagger assistance devices (AFADs) so that they can stay out of the roadway when directing traffic. Temporary traffic lights or yield signs may also be used as an alternative to human traffic guards.