When escort vehicles are required:
A rear escort is required when vehicle length exceeds 120 feet. A rear escort is required when the width of the vehicle and load is over 16 feet 6 inches and travel is on 4 lane roadways. A rear escort or an amber light or strobe light on the power unit and on the rear extremity of the vehicle or load when width exceeds one-half the roadway up to and including 16 feet 6 inches and travel is on 4 lane roadways. A front escort is required when: Width is up to and including 14 feet 6 inches and exceeds one-half the roadway and travel is on 2 lane roadways with lane width less than 12 feet OR Width is up to and including 14 feet 6 inches and exceeds one-half the roadway and travel is on 2 lane roadways with lane width 12 feet or more without sufficient shoulders OR Width is over 14 feet 6 inches and travel is on 2 lane roadways. A front escort - or an amber light or strobe light on the power unit and on the rear extremity of the vehicle or load, when width is up to and including 14 feet 6 inches and exceeds one-half the roadway and travel is on 2 lane roadways with lane width 12 feet or more with sufficient shoulders. A front escort with mounted height pole is required when height exceeds 14 feet 4 inches up to and including 20 feet. An escort but no height pole is required after 20 feet.Escort Requirements
Escorts must be at least 18 years old, possess a valid Class A, B, C or D driver's license, and carry proof of public liability insurance in the amounts of $100,000/$200,000/$50,000. The escort vehicle must be approximately the size of a normal passenger automobile or pickup and must have an amber revolving light. The light must be at least 7" high and 7" in diameter, with at least a 100-candlepower lamp providing 360º warning (or a strobe light), and be mounted on top of the escort vehicle which must be burning while escorting a permit load. An 18" square red flag must be on each corner of the front bumper of the vehicle.
Source of information: https://iowa.gotpermits.com/iaps/General_Provisions.pdf
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