INFORMATION SHEET
KING COUNTY REGIONAL 800 MHz TRUNKED
RADIO SYSTEM
Updated: October 1999
BACKGROUND: The King County regional 800 MHz trunked radio system was approved by voters in an election held on September 15, 1992. King County voters authorized a special levy to be assessed for a period of three consecutive years to finance the development of an 800 MHz trunked radio system, including compatible mobile and portable radios, base stations, a microwave transmission network, network controllers and other related equipment. The levy was collected in 1993, 1994 and 1995 at a rate not to exceed $.16 per $1000 of assessed valuation, for a total amount of $57,016,764.
The primary purpose of the system is to provide emergency radio communications services for all the police, fire, emergency medical services, public school districts and public hospitals within King County. The secondary purpose of the system is to provide, to the extent possible within the constraints of available funding and limited spectrum availability, sufficient capacity within the system to service other public agencies with emergency response duties.
The regional system consists of several subsystems joined together by electronic switching equipment to provide highly reliable region-wide communications. Each subsystem has been implemented by a subregional system management group, also called a subregion, that will own and manage portions of the system. Subregions include: The City of Seattle, Valley Communications Center, Eastside Public Safety Communications Agency (EPSCA), and King County. The governing body for the EPSCA Subregion includes the cities of Bellevue, Kirkland, Redmond, Mercer Island and Issaquah. The governing body for the Valley Communications Subregion includes the cities of Auburn, Kent, Renton, and Tukwila.
Central coordination for the regional system is provided by the Regional Communications Board. This Regional Communications Board is a joint board, and consists of one representative from each subregion and an at-large member who represents the interests of system users who do not have a voting representative on the governing body of any subregion. Each member of the Board has equal voting authority. Decisions concerning network design require unanimous approval by the Board.
SYSTEM DESIGN: The Subregions have worked cooperatively through the Regional Communications Board to implement a design for the entire county-wide system that is able to meet performance needs within the limited number of frequencies and available funding. Some of the major design considerations related to coverage, performance standards, and the sheer number of diverse government users within King County.
A majority of King County’s population lies in a region that is within 140km of the Canadian border. Treaties between the US and Canada allow agencies in these border areas to only have clear use of about 1/2 of the available 800 MHz spectrum. All other spectrum utilization needs to be on a non-interference basis to the neighboring country. Given the unique terrain and topography of the Puget Sound region, the design of the system needed to carefully plan spectrum utilization so that capacity needs could be met without causing interference problems to our Canadian neighbors.
King County covers approximately 2,200 square miles. Almost 90 percent of the almost 1.7 million population live in the western half of the county. The eastern portion of the county reaches to the crest of the Cascade Mountains, where radio coverage is more difficult to provide. This area is sparsely populated but has several major transportation corridors that have heavy commercial and recreational use.
The large number of separate governments within King County include 38 cities, 24 fire districts, the Port of Seattle, 4 hospital districts, 20 school districts, and 43 water and sewer districts. There are a total of 68 separate public safety agencies delivering police, fire and EMS services to our citizens. Over the years these agencies had developed a collection of over 100 separate VHF, UHF and 800 MHz radio systems.
The levy-funded 800 MHz radio system has been designed with the capacity to meet the diverse needs of these users with one compatible radio network. This network has sufficient capacity to meet the growth needs of our region; it provides the coverage capabilities essential to public safety services that many of the older systems lack; it has a high likelihood of surviving a natural disaster for the delivery of reliable service; and it provides for direct communications between jurisdictions to better meet mutual response needs during single incidents or during a disaster.
The county-wide network is essentially configured as three subsystems that work through common network controller equipment. Subsystems include the City of Seattle subsystem, the EPSCA subsystem, and the subsystem that was jointly developed by King County and Valley Communications Center. By connecting all sites within the subsystems to common network controller equipment, it is possible to implement talkgroups on the system that have seamless coverage over the entire county. Please see attached diagrams of the overall system design and site distribution. The system has been designed for portable grade coverage wherever possible and the system loading is patterned so that all areas of the county experience relatively similar system capacity access. The overall county-wide system has been designed with sufficient frequency capacity to include most, if not all, general government users within King County.
The regional system currently uses analog audio technology rather than digital audio technology. Analog technology for 800 MHz trunking is proven and reliable, and provides better audio quality with fewer sites when compared to a digital trunking system. Further, an industry standard is not yet fully developed for digital trunking technology for public safety communications systems. At the time system design decisions were being made (and in some respects even to this day) investment in public safety digital trunking infrastructure involves some risk of selecting technology that may not be supported into the future as final standards emerge. Because digital technology does appear to be the direction for communications in the future, however, the system uses, to the extent possible with today’s technology, infrastructure equipment that can be migrated to digital technology in the future when the need exists, when the costs are more reasonable, and when the technology is stable.
STATUS OF INFRASTRUCTURE CONSTRUCTION: Following design of the system and equipment order, staging and delivery, the build-out of the system has progressed in several phases.
First, the core system infrastructure and the North microwave loop were constructed, and an initial set of trunked system equipment was put in place to serve the City of Seattle.
Following testing and confirmation that all of this worked properly, some Seattle functions began using the system, and the EPSCA Subsystem was constructed, tested, and put online. Users then began conversion to the new system, and Seattle expanded their use of the system as the overall coverage and capacity grew.
Concurrent with this, work began on the South microwave loop and the King County/Valley Com (KC/VC) Subsystem at sites where towers and buildings already existed. The KC/VC Subsystem was the only portion of the system that needed to build completely new sites, so initial trunked system operations began from sites where towers and buildings already existed. Subsequent to testing and optimization of the initial sites in the KC/VC Subsystem, customer agencies began their migration to the new network.
A major revision of the Seattle Subsystem then took place to convert three of the standalone sites into a simulcast configuration.
The following table outlines some of the general statistics on the system:
Subregion
Number of Public Safety Customer Agencies
Number of Sites to Build
Number ofSites Online
Original Customer Radio Count Estimate
Revised Customer Radio Count Estimate
Approximate Number of Radios Online Today
Seattle 2 7 7 2,600 4,500 4,000
EPSCA 19 6 6 1,100 2,500 2,250
King County/ Valley Com 47 13 12* 2,800 5,500 5,000
Common Central Controller Sites n/a 2 2 n/a n/a n/a
Total 68 28 27 6,500 12,500 11,250
*A temporary site is operating at King Lake until the Ring Hill site is constructed in late 1999.
Work is now being completed on the remaining sites in the King County/Valley Com simulcast portion of the system. Following is a brief summary of the status of each site left to be completed:
View Park - The View Park site (on the Kitsap peninsula) was put on the air this month.
Ring Hill - A site is being developed at a closed King County Solid Waste landfill in the Woodinville/Duvall area. The land use permits were issued for this site, but they were challenged through an appeal to the Hearing Examiner and then to Superior Court by residents abutting the site. Ultimately, the land use permits were upheld, and final construction documents were completed. Construction has started at this site and we hope to have the site on the air by late December or early January. As an interim measure, a temporary site has been installed at the Washington State Patrol’s King Lake site.
The Regional Communications Board is also evaluating several final adjustments to the common equipment infrastructure, subsystem capacities, and subsystem configurations, that need to be made before we can call the overall network complete. These changes will be accomplished concurrent with the completion of the KC/VC Subsystem.
Last updated: 2/1/00