Regional Trends and Economic Development

Introduction

Demographics such as population size, household income, household size, and employment play a key role in transportation planning process. Changes in demographics directly impact travel behavior and patterns. Travel patterns and behavior help in estimating demand for travel which in turn provide information to project on what transportation improvements would be required for the next 25-year planning horizon.

The growth and distribution of population influences land use policies and regulations. People select places to live, work, shop, and exchange goods and services. They also select places for social interaction and recreation. Travel patterns and land use are interdependent and set an urban growth pattern. A population and employment forecast for the study area is needed to estimate potential transportation trips to adequately accommodate those trips on the transportation network.

The Metropolitan Planning Organization (MPO) is required to perform transportation planning activities within an urbanized area at minimum. This includes planning activities that analyze the regional impact of population and employment.

Population Growth

A review of Census and state data will show the trends for the population of an area. The net change in population is a sum total of the changes to the base population and immigration or out-migration. The immigration to an area is prompted by three factors: weather, employment, and education.

Economic and Employment Characteristics

A comparative review of decennial Census data will provide demographic trends in the MPO area. Census data will also provide data on the Median Household Income, thereby identifying persons living below poverty level. Census data will also identify trends in the unemployed persons in workforce compared to prior years. The trends of other factors such as transportation disabled and persons per household are important indicators in the transportation planning process.

Vehicle Ownership

An analysis of the Census data will show trends in auto ownership by household over a ten year period and the percentage of households with three or more cars. Also of significance is the number of households with no vehicle available.

Means of Transportation to Work

Census data also provides the Means of Transportation to Work data. The data shows the trends in the drive alone trips in an urbanized area of the MPO as well as the trend in carpooling and the use of public transportation.

As stated earlier, population forms the basis of estimating trips. For accurate simulation of existing travel demand, demographic information is compiled for a reasonable size unit called the Traffic Analysis Zone (TAZ). An in-depth analysis of demographic trends is done to estimate the base year and the future years' trip generation to estimate the transportation system needs for the future. The MPO, in cooperation with other public and private agencies, develops a base year and population and employment data projected a minimum of 20-years to be used in the Travel Demand Model.

Employment

The urbanized area is the major economic center for a region and may include multiple cities. The urbanized area provides employment in a variety of industries and institutions such as industrial, retail and service sectors. Major employment generators such as a port, university or major employer play key roles in regional commerce and transportation.

Employment data from the local workforce board will also illustrate the percentage of persons employed outside of their county of residence, also referred to as inter-county workers.

Travel Demand Forecast

The MPO provides the Texas Department of Transportation, Transportation Planning and Programming Division, the employment and population data for the base year, forecasted year, and the existing transportation network to validate and calibrate the travel demand model for the study area. The model is calibrated through an iterative process where the data is adjusted until assigned traffic volumes match counted volumes.

The Base Year Model is capable of replicating existing traffic volumes and Vehicle Miles Traveled (VMT). The forecast model, assumes that by providing the base year model with forecasted demographic data and forecasted highway systems, the MPO can estimate travel demand on the future system. Once the Travel Demand Model is validated, forecasted demographics and network improvements can be used to validate the base year trip rates, trip length, frequency distributions, and roadway speed and capacity values.

The Travel Demand Model is a valuable tool because it provides data that will help public officials and the MPO to make decisions on which projects and road improvements should be developed in the area, not only a long term, but also a short term for the Transportation Improvement Program. The travel demand model is also a valuable tool in helping to:

  1. Identify major employment centers.
  2. Establish and improve zoning and land use policies.
  3. Establish and improve utilities' systems.
  4. Encourage economic development.
  5. Analyze traffic impacts due to new development.
  6. Analyze travel patterns.

The MPO staff will need to plan to update population, employment, and network data every five years to facilitate the decision making process and the public's understanding of the transportation infrastructure development process.