THE 1972 SUBURBAN COOK COUNTY COMMUNICATIONS PLAN PROPOSED 24 POLICE RADIO NETWORKS TO RELIEVE SEVERE RADIO CONGESTION. TO DATE, 13 NETWORKS ARE OPERATIONAL AND ANOTHER 7 HAVE RECEIVED FUNDING APPROVAL BUT HAVE NOT YET INSTALLED NEW EQUIPMENT. THE MAJOR IMPACT CRITERIA WERE AVERAGE DELAY TIME TO GET A RADIO MESSAGE ON THE AIR, RADIO SYSTEM RELIABILITY, AND COST EFFECTIVENESS. THE ANALYSIS INDICATES A SIGNIFICANT IMPROVEMENT IN REDUCING AVERAGE DELAY TIME. PRIOR TO 1972, ONLY 13 PERCENT OF THE RESIDENTS IN SUBURBAN COOK COUNTY WERE SERVED BY POLICE DEPARTMENTS THAT HAD AN AVERAGE DELAY TIME DURING PEAK PERIODS OF 5 SECONDS OR LESS. IN AREAS WHERE THE 13 NETWORKS ARE OPERATIONAL WITH NEW EQUIPMENT, 81 PERCENT OF THE POPULATION IS SERVED BY DEPARTMENTS WITH RADIO SYSTEMS THAT MEET THE 5-SECOND GOAL. GENERALLY, 64 PERCENT OF RADIO USERS REPORT NO TRANSMITTING OR RECEIVING DIFFICULTY. BY MAKING A SERIES OF ASSUMPTIONS, COST-EFFECTIVE RATIOS WERE CALCULATED FOR EACH NETWORK, (I.E., REDUCTION OF DELAY TIME COMPARED TO NETWORK FUNDING). COMMMUNITIES IN PREVIOUSLY SATURATED NETWORKS HAVE A VERY HIGH COST-EFFECTIVE RATIO, WHILE THOSE COMMUNITIES PREVIOUSLY ALONE IN A NETWORK HAVE A LOW OR SLIGHTLY NEGATIVE RATIO. TABULAR DATA ARE PROVIDED. (AUTHOR ABSTRACT MODIFIED--RCB)