why do police cars have red and blue lights


If a police car is following you with its lights flashing it may be that it is on the way to an emergency, so you should pull over as soon as possible. If it is following you specifically then you may have committed a traffic offence such as speeding or using a cellphone, or you have performed a dangerous or inconsiderate manoeuvre such as not indicating, pulling out in front of someone, or deliberately losing traction, or the number plate of your vehicle has come up as stolen or wanted in relation to a crime. While police vehicles have red and blue lights, ambulances and fire engines only have red lights.


This lighting is called emergency vehicle lighting. It can also be used to make other drivers aware of a hazard when stationary. Emergency vehicles often have flashing headlights to augment the emergency lights. On police vehicles a small arrow board is often included between the lights to direct vehicles. LED-based lighting is the most popular type of lighting as it allows the light bar to be much narrower than with the old style of lights (and hence ). The lights can also be included in the vehicle\’s windscreen, which you\’ll see in unmarked police vehicles.


Blue lights are only used by vehicles that have the authority to pull you over. These include police, customs officers, fisheries officers and marine reserve officers.
People often associate police with the color blue — their cars and uniforms are often this color. The police in our town have cars with all kinds of colors of flashing lights on them — they have white, red, and yellow lights. Their main purpose is to get your attention and to get you to realize that they are police and not some other people with flashing lights.


Non-police cars and trucks usually have yellow flashing lights to warn you that they may be moving slowly or may be making frequent stops. Examples include tow trucks and street sweepers. You want to be able to distinguish these from police and fire vehicles, even late at night when all you can see is their lights, so that you know when to pull over when they come zooming by. Blue isn\’t the greatest color for visual perception, as we answer elsewhere in this archive, but it works fine for the purpose. (published on 10/22/2007)

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