2006 Water Comprehensive Plan - City of Bellevue

individual Transportation Analysis Zones (TAZ) developed in the early 1980s in conjunctionwith traffic modeling for the City. Each TAZ is a geographic area containing essentiallyhomogenous land use, with roadways as boundaries in most cases. Figure 3-1 illustrates theTAZs within the water service area.To calculate population within each TAZ, the Planning and Community DevelopmentDepartment applied estimated dwelling unit and employment densities to known quantities ofsingle- and multi-family units. Building square footage was used as the basis for calculatingfuture development trends in commercial areas. The densities used were based on the mostrecent census data which is updated every five years. Current population densities are2.8 persons per household in single-family units, and 1.8 persons per household in multi-familyunits. Vacancy rates are 5 percent for single-family, and 7 percent for multi-family units.Population and employee density is summarized in Table 3-1.Table 3-1Population and Employee DensityLand Use CategoryExisting (2003):OfficeRetailIndustrialResidentialSingle-FamilyMulti-FamilyYear 2020:OfficeRetailIndustrialResidentialSingle-FamilyMulti-FamilyEmployee per Ksqft aPersons perHouseholdPercent VacancyCBD b Non-CBD CBD Non-CBD3.12.51.0——3.12.51.0——3.12.51.7——3.12.51.7—————2.81.8———2.71.71075—101075—1010107571010757a Ksqft = one thousand square feet.b CBD = Central Business DistrictThe Bellevue Planning and Community Development Department estimates that saturationdensities will be realized within the City by the year 2020 for all areas except the CentralBusiness District (CBD). Saturation densities for the CBD are assumed to occur by the year2040. Population projections were provided for the years 2020 and the build out condition,assumed to be 2040. These projections were used to estimate the projected populations for theyears 2011 (6 year planning horizon) and 2025 (20 year planning horizon). The land use andnumber of units in each TAZ are consistent with the guidelines established by the GrowthManagement Act (HB2929) and were the best available information when this portion of thecomprehensive plan was prepared.3-2