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Portland Bureau of Transportation

Phone: 503-823-5185

Fax: 503-823-7576

1120 SW Fifth Ave, Suite 800, Portland, OR 97204

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TSDC Definitions of Terms

Definitions of Important TSDC Terms

Gross Floor Area (GFA):  The sum (in square feet) of the area of each floor level in the building, including cellars, basements, mezzanines, penthouses, corridors, lobbies, stores and offices, that are within the principal outside faces of exterior walls, not including architectural setbacks or projections. Included are all areas that have floor surfaces with clear standing head room (6 feet, 6 inches minimum) regardless of their use.  If a ground-level area, or part thereof, within the principal outside faces of the exterior walls is not enclosed, this GFA is considered part of the overall square footage of the building.  However, unroofed areas and unenclosed roofed-over spaces, except those contained within the principle outside faces of exterior walls, should be excluded from the area calculations.  For purposes of trip generation and parking generation calculations, the GFA of any parking garages within the building should not be included within the GFA of the entire building.  The unit of measurement for office buildings is currently GFA; however, it may be desirable to also obtain data related to gross rentable area and net rentable area.  With the exception of buildings containing enclosed malls or atriums, GFA is equal to gross leasable area (GLA, explained next) and gross rentable area.

Gross Leasable Area (GLA):  The total floor area designed for tenant occupancy and exclusive use, including any basements, mezzanines, or upper floors, expressed in square feet and measured from the centerline of joint partitions and from outside wall faces.  For purposes of trip generation and parking generation calculations, the floor area of any parking garages within the building should not be included within the GLA of the entire building.  GLA is the area for which tenants pay rent; it is the area that produces income.  In the retail business, GLA lends itself readily to measurement and comparison; thus, it has been adopted by the shopping center industry as its standard for statistical comparison.  Accordingly, GLA is used for shopping centers.  For strip centers, discount stores and freestanding retail facilities, GLA usually equals GFA.

Definitions of Land-use Categories

The following land-use definitions are derived from the ITE Trip Generation (9th Edition) publication.  They have been modified as appropriate for the City ofPortland.  ITE land-use codes are shown; where multiple codes are listed, the code used for trip generation is marked with an asterisk (*).


Single Family, detached:  Includes all single-family detached homes on individual lots and clustered homes of up to 3 units.  (ITE # 210)

Multi Family: A building or buildings designed to house four or more families living independently of each other. Includes low-rise, mid-rise, and high-rise apartments.  (ITE # 220)

Senior Housing: Residential units similar to apartments or condominiums restricted to senior citizens. (ITE # 251)

Accessory Dwelling Unit. A second dwelling unit created on lot with a house, attached house, or manufactured home. The second unit is created auxiliary to, and is always smaller than the house, attached house, or manufactured home.  (ITE # 210 calculated at 50% of the trip generation rate) 

Row House / Townhouse/ Condo: A building or buildings designed to house two or more families living independently of each other.  Includes condos and attached townhouses of 2 units or more.    (ITE # 230)

Nursing Home: A facility whose primary function is to provide chronic or convalescent care for persons who by reason of illness or infirmity are unable to care for themselves.  Applies to rest homes and convalescent centers. (ITE # 620)

Congregate Care/Assisted Living: One or more multi-unit buildings designed for people who are unable to live independently due to physical or mental handicap.  Facilities may contain dining rooms, medical facilities, and recreational facilities.  (ITE # 253)


Bank: A building, with or without a drive-up window, for the custody or exchange of money, and for facilitating the transmission of funds. (ITE # 911, 912*)

Day Care: A facility for the care of infant and preschool age children during the daytime hours.  Generally includes classrooms, offices, eating areas, and a playground. This also includes preschools.   (Note:  This does not apply to day care homes, family day care, mini-day care centers or mini-schools, rates for which must be separately calculated.) (ITE # 520)

Library: A public facility for the use, but not sale, of literary, musical, artistic, or reference materials. (ITE # 590)

Post Office: A building with service windows for mailing packages and letters, post office boxes, offices, vehicle storage areas, and sorting and distribution facilities for mail. (ITE # 732)

Hotel/Motel: A place of lodging providing sleeping accommodations.  May include restaurants, cocktail lounges, meeting and banquet rooms or convention facilities.  (ITE # 310*, 320)

Service Station/Gasoline Sales: A facility used for the sale of gasoline, oil, and lubricants.  May include areas for servicing or repairing vehicles.  May include a minimart (not to exceed 1,500 square feet) and/or carwash. (ITE # 946)

Movie Theater: Consists of audience seating, with one or more screens, and a lobby and refreshment stand.  Typically includes matinee showings.  (ITE # 444)

Carwash: Manual operations where the driver parks and washes the vehicle in a stall, or an automated facility for the same purpose. (ITE # 947)

Health Club: Privately owned facility that may include swimming pools and whirlpools, saunas, weight-lifting and gymnastics equipment, exercise classes, tennis, racquetball, and handball courts.  Features exercise sports and other active physical conditioning, as well as a broader range of services such as juice bars and meeting rooms.  (ITE #s 492*, 493)

Marina: A facility providing moorage for boats. (ITE # 420)


School, K-12: Covers full range of primary and secondary schools.  Includes elementary, junior high, middle school and high school uses. Both public and private schools are included in this land use. (ITE# 520, 530, average)

University/College: Facilities of higher education including two-year, four-year and graduate-level institutions. (ITE # 550)

Church: A building providing public worship facilities.  Generally houses assembly hall or sanctuary, meeting rooms, classrooms, and occasionally dining facilities.  (ITE # 560)

Hospital: A building or buildings designed for the medical, surgical diagnosis, treatment and housing of persons under the care of doctors and nurses.  Rest homes, nursing homes, convalescent homes and clinics are separate uses.  (ITE #610)

Park: Parks are typically owned and operated by the City, but may include private uses. They can vary widely as to location, type and number of facilities, including boating or swimming facilities, ball fields, campsites and picnic facilities.   (ITE # 411)


Restaurant: An eating establishment that sells prepared food or beverages and generally offers accommodations for consuming the food or beverage on the premises.  Usually serves breakfast, lunch, and/or dinner; generally does not have a drive-up window. (ITE # 931)

Quick Service Restaurant (Drive-through): An eating establishment that offers quick food service and a limited menu of items.  Food is generally served in disposable wrappings or containers, and may be consumed inside or outside the restaurant building.  Restaurants in this category have a drive-up window.  (ITE # 934)


Miscellaneous Retail: Small strip shopping centers or retail space within a mixed-use building up to 199,999 square feet that contain retail shops specializing in quality apparel, hard goods, and services, such as small restaurants (under 3000 square feet), real estate offices, dance studios, and florists.  (ITE #826)
For the purpose of this definition a mixed-use building consists of two or more of the following land use categories; residential, shopping/retail, entertainment, hotel/motel, or office.  These land use categories have similar internal trip-making characteristics.  Other land use categories, such as warehouse or manufacturing, do not share the same internal trip-making characteristics.

Shopping Center:  An integrated group of commercial establishments that is planned, developed, owned, or managed as a unit and are 200,000 square feet and over. On site parking facilities are provided, and administrative office areas are usually included. In addition to the integrated unit of shops in one building or enclosed around a mall, Shopping Centers may include certain peripheral buildings located on the perimeter of the center adjacent to the streets and major access points.  (ITE #820)

Supermarket:  Retail store (greater than 5,000 gross square feet [GSF]) that sells a complete assortment of food, food preparation and wrapping materials, and household cleaning and servicing items. Supermarkets may also include ATMs, bakeries, books and magazines, floral shops, limited service banks, photo centers, pharmacies and video rental areas.  Some facilities may be open 24 hours a day. If gasoline sales are included on-site, use Gasoline Sales TSDC times number of fueling positions to calculate additional trips. (ITE # 850)

Convenience Market: A use that combines retail food sales with fast food or take-out food service; generally open long hours or 24 hours a day. If gasoline sales are included on-site, use Service Station/Gasoline Sales TSDC rate. (ITE # 851)

Free-standing Discount Store: A free-standing store or warehouse that offers centralized cashiering and a wide range of merchandise and/or food products.  May include items sold in large quantities or bulk.  Often is the only store on a site, but can be found in mutual operation with its own or other supermarkets, garden centers and service stations, or as part of community-sized shopping centers.  Fred Meyer stores, Costco, and big box consumer electronic/ computer/toy stores are examples of this land use.  If gasoline sales are included on-site, use Gasoline Sales TSDC rate times number of fueling positions to calculate additional trips.  (ITE #s 813, 815*)

Car Sales (New/Used): Facilities are generally located as strip development along major arterial streets that already have a preponderance of commercial development.  Generally included are auto services and parts sales along with a sometimes substantial used-car operation.  Some dealerships also include leasing activities and truck sales and servicing. (ITE # 841)


Administrative Office: An administrative office building houses one or more tenants and is the location where affairs of a business, commercial or industrial organization, professional person or firm are conducted.  The building or buildings may be limited to one tenant, either the owner or lessee, or contain a mixture of tenants including professional services, insurance companies, investment brokers, and company headquarters.    (ITE # 710)

Medical Office/Clinic: A facility that provides diagnoses and outpatient care on a routine basis but does not provide prolonged in-house medical/surgical care.  A medical office is generally operated by either a single private physician/dentist or a group of doctors and/or dentist. (ITE # 720)


Light Industrial/Manufacturing:  A facility that may contain industrial or manufacturing uses.  Manufacturing facilities have the primary activity of converting raw materials or parts into finished products.  In addition to the actual production of goods, manufacturing facilities may also have office, warehouse, research and associated functions. Light Industrial facilities may be characterized by a mix of manufacturing, service and warehouse functions.  Many produce goods by assembling other products, such as assembly of computers or other electronics.  (ITE # 130)

Warehouse/Storage: Warehouses are primarily devoted to the storage of materials, but may also include limited office and maintenance areas. (ITE # 150)

Self Storage: Buildings in which a number of storage units or vaults are rented for the storage of goods.  Each unit is physically separated from other units, and access is usually provided through an overhead door or other common access point.  (ITE # 151)

Truck Terminal: A facility where goods are transferred between trucks, trucks and railroads, or trucks and ports.  (ITE #30)