They used to scope out Rt29 south near the PWC border... people would buy donuts at the Dunkin Donuts on 29 in Centreville and leave that way. Now those buyers have gotten wise and are going back north on 29 to get on 28 and the police have moved their checkpoint accordingly.
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for good info, try:
Free online FCPD scanner feed
http://www.broadcastify.com/listen/feed/15175/web
FFx County Fire and Rescue scanner feed
http://www.radioreference.com/apps/audio/?feedId=1620
http://www.metro.co.uk/weird/78499-cops-use-chopper-to-buy-doughnuts