From New Mexico State Highway and Transportation Department Standard Specifications for Highway and Bridge Construction:

"618.2.1 Certification
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Before commencing work that requires flagger traffic control, submit a copy of the 'Flagger Training' certificate (wallet sized card) issued by ATSSA (American Traffic Safety Services Association), ACNM (Associated Contractors of New Mexico), FHWA (Federal Highway Administration), or an agency or firm approved by the Department.

618.2.1.1 Re-certification
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Flaggers must obtain refresher training which meets the requirements of ATSSA, ACNM, FHWA, or agency or firm approved by the Department prior to the fourth anniversary date shown on the current certificate."