Speed Cameras in Seattle?

Question

I was driving on Seattle's I5 North from Seattle Tacoma airport to Lynnwood, WA. The highway seems to be a 60mph zone; I was going around 70-73mph. As I was about 15 miles from the airport, I heard a strange sound, and it sounded like a siren. Someone told me it might have been a speed camera that caught me going a little fast. First, are there any speed cameras on I5 North in Seattle? If there are, do they make a siren noise to let you know they caught you? It was late, and I did not notice a flash so I think I am safe. However, I am not from here so I did not know the standard practices here, and that person's comment that speed cameras here do that has made me concerned.

Thanks.

Answer 1

I am in the Puget sound and can tell you, WHAT?!  Not on the freeway, dude.  What good would a camera do?  They have stepped up on patrols though.

Answer 2

The only cameras we have in this area are red light cameras and school zone cameras.

Don't worry! The average Seattle driver goes 70 on I-5 anyway...