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Radar speed signUnited States

An introduction to the traffic rules and road signs of United States. Learn about driving, road safety and much more in our illustrated book, with answers to frequently asked questions.

For informational purposes only. Always follow official regulations. Some content and images were created with AI assistance.

Traffic signs
Traffic rules
United States

37. Radar speed sign

A radar speed sign warns drivers that vehicle speeds may be monitored by a fixed camera, mobile radar, lidar or average-speed enforcement system. It reminds drivers to check and respect the applicable speed limit.

The sign does not normally establish the speed limit itself. Drivers must follow the general, posted or variable speed limit applying to the road and must not brake suddenly merely because speed enforcement is indicated.

Speed Checked by Radar sign on the Golden Gate Bridge. (California, United States)
Wikimedia.org • Hallows AG • CC BY-SA
Is a radar speed-feedback display the same as an enforcement-camera warning in the United States?

No. A radar speed-feedback display can show the approaching vehicle’s speed; a photo-enforcement warning refers to an enforcement arrangement. Both are distinct from a regulatory SPEED LIMIT sign.

🔗 mutcd.fhwa.dot.gov • FHWA MUTCD11th Edition including Revision1 December2025 — relevant warning/regulatory/guide signs, lines and restroom symbols

Does a radar speed sign set a new speed limit in the United States?

Not by itself. Obey the posted regulatory speed limit and any legally effective temporary or school-zone limit. An advisory or speed-feedback display does not cancel the applicable restriction.

🔗 mutcd.fhwa.dot.gov • FHWA MUTCD11th Edition including Revision1 December2025 — relevant warning/regulatory/guide signs, lines and restroom symbols

Can a driver assume there is no speed enforcement where no camera sign is displayed in the United States?

No. Enforcement methods and notification requirements vary by state and locality. Do not infer that exceeding the posted limit is permitted when a camera-warning sign is absent.

🔗 mutcd.fhwa.dot.gov • FHWA MUTCD11th Edition including Revision1 December2025 — relevant warning/regulatory/guide signs, lines and restroom symbols

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