Ask a Trooper: What’s that small blue light on traffic lights?

Published 8:45 pm Tuesday, January 14, 2025

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Ask a Trooper by Troy Christianson

Question: I’m wondering about a light that seems to only be on at night on the traffic lights. It’s a small purple or blueish light that’s near the traffic lights. I’ve tried to figure out what its use is or if it’s a camera. I’ve asked other people what it means and I’ve never met anyone who knows what it is. Thank you!

Troy Christianson

Answer: What you are talking about is a blue light, and they are visible during the day. How they work and what are they used for:

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1. Signal activation: The blue lights are wired into the traffic signal system and turn on when the traffic light changes to red.

2. Officer visibility: From a distance, officers can see the blue light, indicating that a vehicle has entered the intersection while the signal was red.

3. Enforcement: This allows officers to effectively and safely enforce red light violations, even if they are observing the intersection from a distance.

The blue lights make it easier for officers to see and enforce red light violations, improving traffic safety. The blue lights allow officers to observe intersections from a safe distance and pull over violators without putting themselves or other drivers at risk. The increased enforcement provided by blue lights aims to deter drivers from running red lights, leading to fewer crashes and improved traffic flow.

You can avoid a ticket — and a crash — if you simply buckle up, drive at safe speeds, pay attention and always drive sober. Help us drive Minnesota toward zero deaths.

If you have any questions concerning traffic-related laws or issues in Minnesota, send your questions to Sgt. Troy Christianson, Minnesota State Patrol, at 2900 48th St. NW, Rochester MN 55901-5848; or reach him at Troy.Christianson@state.mn.us.

Troy Christianson is a sergeant with the Minnesota State Patrol.