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Comprehensive Plan Glossary

This Glossary, updated June 19, 2012, contains an alphabetical listing defining terms as they are used in the context of the Comprehensive Plan. These terms are not intended to be the same definitions as used in the County's Zoning Ordinance. Rather, they are intended only to explain terms used in the Plan.     Download Glossary(PDF)

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TAX CREDITS: A program under Federal IRS regulations (Low Income Housing Tax Credit Program) which provides tax credits in return for investment in housing developments where a portion of the units are subject to rent limits for tenants who meet income eligibility requirements. TDM: See Transportation Demand Management. TIMED TRANSFER CONCEPT: A concept of transit planning whereby public transportation services are scheduled so that transfer times are minimized at transfer points, typically park and ride lots, transit centers, and rail stations. TMA: See Transportation Management Association. TRAILS: A pathway constructed of various materials such as asphalt, stone dust, or natural surface that is used for recreation, or as an alternative mode of non-motorized transportation, or both. TRANSIT: See Mass Transit. TRANSIT ORIENTED DEVELOPMENT (TOD): Transit-oriented development (TOD) in Fairfax County is defined as compact, pedestrian- and biking-friendly, mixed-use development containing medium to high density residential, office and retail uses within walking distance of certain rail transit stations identified in the Area Plans. Well-planned TOD should incorporate good design principles and an appropriate mix of uses around rail transit stations to promote transit usage and create vibrant neighborhood centers at these locations. TRANSIT STATION AREAS (TSAs): These areas adjacent to Metrorail Stations are directly influenced by the presence of access points to the Metrorail system. Transit station areas promote a land use pattern that supports Metrorail by encouraging a mix of uses in a compact, pedestrian-friendly urban form within walking distance of the rail station. The transit-oriented development (TOD) area may be generally defined as a ¼ mile radius from the station platform with a density and intensity tapering to within a ½ mile radius from the station platform or a 5-10 minute walk. Within the region, Metrorail provides a vital public transportation choice that enhances accessibility and reduces the reliance upon single occupancy vehicle use. Transit Station Area boundaries are strongly influenced by the area's access characteristics and the relationship of the station to surrounding stable neighborhoods. TRANSIT TRANSFER CENTER: Facility where public transportation services, usually bus services and sometimes rail service, are coordinated so that passenger transfers are facilitated. Facility typically includes passenger waiting and information areas, bus parking areas, and does not including parking. TRANSPORTATION DEMAND MANAGEMENT (TDM): Actions taken to reduce single occupant vehicle automobile trips or actions taken to manage or reduce overall transportation demand. TRANSPORTATION MANAGEMENT ASSOCIATIONS (TMAs): Groups of employers uniting together to work collectively to manage transportation demand in a particular area. TRANSPORTATION SYSTEM MANAGEMENT (TSM) PROGRAMS: This term is used to describe a full spectrum of actions that may be applied to improve the overall efficiency of the transportation network. TSM programs usually consist of low cost alternatives to major capital expenditures, and may include parking management measures, ridesharing programs, flexible or staggered work hours, transit promotion, or operational improvements to the existing roadway system. TSM includes Transportation Demand Management measures as well as H.O.V. use and other strategies associated with the operation of the street and transit systems. TRIBUTARY STREAM: Any perennial stream that is so depicted on the most recent U.S. Geological Survey 7 1/2 minute topographic quadrangle map (scale 1:24,000). TSA: See Transit Station Area. TSM: See Transportation System Management. TYSONS CORNER URBAN CENTER: Tysons Corner is a significant economic engine to the region. The vision for Tysons Corner includes a dynamic urban center marked by the socioeconomic diversity of residents and workers; a wide range of opportunities and activities; the quality of buildings, aesthetics, and open spaces; and connections and accessibility for all. Tysons Corner includes four transit-oriented development (TOD) areas surrounding four Metrorail stations.