what do red lights on police cars mean?

[dpbird90]

just on the way home, saw a marked police car pulled someone over, but instead of blue lights the ones on the roof were flashing red. is there any difference between this and one with blue lights on top? sorry for any bad punctuation, i am typing this on my crappy motorola!

[Haytch]

The other day I saw a police car stopped with flashing reds instead of blues too, not sure why the need to switch them to blue though...

[EDLT]

Its more eye-catching I guess. It might stop mongs from standing on the brakes whenever they see blue lights.

[Shmee]

Red from behind when stopped, blue from in front.

[Cock Womble 7]

Shmee said:

Red from behind when stopped

I often see police cars sat (alone) on the hard shoulder or slip road with the rear red lights flashing and wondered what (if anything) this "means".

Is it just a simple "I am here" - are the red lights just additional to the hazards, or are we supposed to act on this display somehow?

[MGZRod]

I see this quite a lot. I assume it's to tell which direction the car is facing, so you can prepare to maneuvre (or not if you see red!)

I.e If you see blue & red lights when you glance at mirror, no need to move to side of road.
Or if you see it ahead parked up, you may need to move over to avoid it (pulled someone over etc)

[parapaul]

It's something along these lines:

Blue flashing lights are very eye catching, and it's an inbuilt reaction for most drivers to either have a look, slow down, or do something else that would otherwise distract them from the rest of their drive.

When plod are stopped, particularly on the hard shoulder, they use the flashing rear reds as a warning to approaching traffic of the hazard they are creating or dealing with, without offering any more distraction than necessary to oncoming traffic.

[Funk]

Red is also at the long end of the light spectrum and therefore more easily seen at a distance by the human eye. This is why traffic lights are red for stop, as well as brake lights and tail lights.

[Baryonyx]

Yes, rear reds are used when stopped facing in the same direction as the movement of traffic on the carriageway, for instance if you pull someone over for using their phone etc etc. That said, cars parked across roads for traffic management (at a crash, for instance) will use their blues still. The rear reds are just a very noticeable hazard light.

There is usually a separate control on the panel for "rear reds" and a "runlock" control for when you're going to need blue lights on a stationary vehicle.

[Gwagon111]

Funk said:

Red is also at the long end of the light spectrum and therefore more easily seen at a distance by the human eye. This is why traffic lights are red for stop, as well as brake lights and tail lights.

Yellow is the colour that human eyes are most sensitive to.

[Vipers]

I seem to recall seeing this in London a couple of years ago, asked a couple of lovely lady bobbies, they told me they were the armed brigade?

Mind you, could only be within London itself, or things have changed.

[deveng]

Before reading the OP I wanted to be a smart arse and say "it's braking" based on the title.

[insanojackson]

its simply an additional warning to stop inatentive drivers from rear ending you whilst stopped.