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Demographics

Trip generation primarily requires two types of data: socioeconomic data and travel behavior data. The MPO, in cooperation with TPP, develops the following socioeconomic data for each traffic analysis zone in the urban area for the base year and each forecast year:

• Total Population - The total population for each traffic analysis zone in the urban area for the base year and each forecast year. It is recommended that the Texas State Data Center (TSDC) be referenced when developing base and forecast year(s) population control totals.

• Number of Households - The total number of households for each traffic analysis zone in the urban area for the base year and each forecast year. A household is defined as an occupied dwelling unit. Since dwelling units may be vacant, households and not dwelling units are provided.

• Average Household Size - The average household size for each traffic analysis zone in the urban area for the base year and each forecast year.

• Total Employment - The total employment for each traffic analysis zone in the urban area for the base year and each forecast year. The total employment should represent the summation of Basic, Retail, Service, Education, and Special Generator employment.

• Basic Employment - The total employment in North American Industry Classification System (NAICS) categories of mining, construction, manufacturing, wholesale trade, transportation, communication, and public utility groups.

• Retail Employment - The total employment in NAICS retail industry groups.

• Service Employment - The total employment in NAICS financial, insurance, real estate, education, government, and service industry groups.

• Education Employment - The total employment in NAICS education groups. Public education employment is segregated because school districts typically report the headquarters office only along with the total school district employment. The distinct school locations are not individually reported in the Texas Workforce Commission (TWC) database but must be distinguished or identified when the demographic database is developed.

• Median Household Income - Median household income not adjusted for inflation. Median household income of the zone is collected rather than average income to avoid outlier's unduly influencing the income characteristics of individual zones.

• Special Generators - Specification of special generators by zone and the specific information needed for identified special generators. Examples of special generators include but are not limited to regional malls, airports, colleges, and hospitals. To properly estimate the total number of trips by trip purpose generated by a special generator, it is necessary to have additional information regarding the special generator so an appropriate trip rate can be used. For example, trips to a university will often be estimated based on a combination of student enrollment, the number of students residing on and off campus, and the total employment on campus.