In order to do this you must first get the attention of the police, easiest way is just just crash in to a police car and carry on driving. After some amount of time (I think level 2 heat) they will start blocking the roads with other cars, in order to unlock this trophy you have to drive between the small gaps between the police cars.
Doing this you will simply hit either the rear and/or front of two police cars causing you to smash through the barrier but not crash like you would if you hit the cars side on.