(Portland, OR)  --  A Portland Police Bureau operation is over, resulting in 21 citations being issued.  The Vision Zero traffic safety mission took place on North Interstate Avenue between North Multnomah and North Lombard Streets yesterday from 10 to 11 a.m.  The goal of the effort is to eliminate traffic deaths and serious injuries.  The Bureau reports eleven of the citations were issued for use of cell phones while operating a vehicle.