Four north Texas police departments launch a regional push to combine some operations.

   Keller, Southlake, Westlake and Colleyville  share borders and now share a jail and emergency communication center.  Colleyville Police Chief Steve Dye says when they looked at the numbers the savings were huge.  It will cut costs by more than 300-thousand dollars a year.  It means one jail, one dispatch center, and officers in all four cities will talk to each other on the same radio channel.   It also means one city can send officers to another city if the call is near their border.  Keller will house the new center in the first such cooperative effort in north Texas.