Police will have getto blasters attached to cruisers:
http://www.wtop.com/?nid=25&sid=1281596New Police Sirens Will Make Your Car Vibrate
WASHINGTON - Perhaps this has happened to you. You're driving, and a police car zooms by you but you never heard the siren or saw the flashing lights.
Metropolitan Police are hoping to prevent that in the future. They plan to phase in a new kind of siren called the Rumbler.
Through woofers attached to the police cruiser, the Rumbler emits low frequency vibrations that you can feel, as well as hear. You're supposed to be able to feel the shaking 200 feet away.
Metropolitan Police realize the Rumbler may startle people the first time they hear it. It's supposed to turn off by itself after 10 seconds.
And those blinking red and blue lights on top of cruisers will burn just blue in the future.