NCTCOG Demographic Forecast Overview North Central Texas 2040 Demographic Forecast Over the course of a thirty-five year period, which began in 2005, the North Central Texas area is expected to add nearly 4.8 million people and 3.0 million jobs. The goal of the North Central Texas 2040 Demographic Forecasts is to project where these people and jobs are likely to locate within North Central Texas thus allowing sub-regional comparative analysis. For the purposes of this study, North Central Texas is comprised of a 12-county area including: Collin, Dallas, Denton, Ellis, Hood, Hunt, Johnson, Kaufman, Parker, Rockwall, Tarrant, and Wise counties. Long-range forecasting is inherently subject to error due to the uncertainty associated with a long time frame and the inability to accurately account for unforeseeable events. Some of the issues affecting the accuracy of the forecast include: • •

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Data errors. While the best available data was used, there are errors in the base-period data due to lack of information or other circumstances. Assumptions. Since it is not possible to know with complete certainly what circumstance will be in the future, some assumptions were necessary. Examples of assumptions included in this forecast are: no major shifts in government policy, no dramatic technological changes, no major changes in human behavior, and no significant changes in the relationships of the various input factors. Geography. In general, as the size of the geography gets smaller, the uncertainty associated with the projection for the area increases. In addition, the known information about the areas varies with some areas having substantial, good data and other areas having much less. The probability that the actual future level of activity will precisely equal the projected level is extremely low for any given area; however, some areas will be closer than others.

Geographies There are multiple planning geographies used during the forecasting process. The primary modeling geography is forecast districts. Districts are comprised of smaller areas called Traffic Survey Zones or TSZs. For the 2040 Forecast, the 12 counties were divided into 242 forecast districts and 5,252 TSZs. The districts, and therefore the TSZs, nest perfectly within another geography called markets. In some instances, a market has only one district making those geographies congruent. A map showing the geographies and their relationships is provided below.

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NCTCOG Demographic Forecast Overview

Forecasting Process The Forecasts were developed using a multi-step process. The first step was the adoption of control totals of households and employment. These were based on data acquired from an independent source 1 and served as a guide in the modeling process. The 12-county control totals for 2035 and 2040 are presented in the table below. Year 2035 2040

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Households 3,497,164 3,745,807

Employment 6,177,010 6,606,517

Dr. Ray Perryman, The Perryman Group, http://www.perrymangroup.com/ 2

NCTCOG Demographic Forecast Overview

District Allocations The second step of the process involved allocating the control totals to forecast districts. This was done in five-year increments from 2010 through 2040 with 2005 serving as a base year. The allocation to the districts was accomplished using an NCTCOG adaptation of the Gravity Land Use Model (G-LUM) model 2 developed at University of Texas at Austin. The G-LUM system is comprised of two main models. One allocates employment; the other allocates households. These are demand driven models in which employment leads residential location. The models were run on the entire 12-county area and compare each district to every other district without regard to city or county boundaries. Key inputs to the models include lagged and base-period employment location by sector, lagged and base-period household locations by income quartile, as well as land use inventories and travel time matrices. Other important factors used by the models include measures of the number of workers per household and household type to employment sector matrices. Data inputs for the models were derived from 2000 Census data, 2005-2009 Census American Community Survey data, NCTCOG major employers and development data, 2005 land use inventories, NCTCOG Transportation Department’s travel networks, and a variety of other data supplied by local entities. The district-level allocations were summarized to counties (12 geographies) and market areas (112 geographies) for presentation to the NCTCOG Executive Board. The market and countylevel forecasts are the adopted and official forecasts for 2035 and 2040. The official forecast data is available at www.nctcog.org/ris/demographics/forecast.asp Disaggregation to Small Areas The final step in the process was a disaggregation of the district forecasts to TSZs. The models used to disaggregate the forecasts to the TSZs are proprietary models developed by NCTCOG Transportation Department staff and use a multi-parameter weighting procedure to determine each TSZ’s proportional share of the district’s forecasted growth. Factors taken into consideration include type and quantity of existing development, amount of developable land, access to transportation facilities, and residential and commercial development capacity. The results of this step were objective TSZ-level figures that were used in further modeling for the Metropolitan Transportation Plan 3.

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The model was developed by Dr. Kara Kockelman (http://www.ce.utexas.edu/prof/kockelman/GLUM_Website/homepage.htm ) based on documentation of the DRAM®, EMPAL®, and LANCON models developed by Dr. Stephen Putman of S.H. Putman Associates 3 Mobility 2035 is the long-range planning document that defines the vision for the region’s multimodal transportation system. To see the plan, visit http://www.nctcog.org/trans/mtp/2035/index.asp 3

NCTCOG Demographic Forecast Overview Local Review In order to help ensure that the small-area projections are consistent with local plans and expectations, one additional step was taken. The TSZ-level figures were made available to local entities for their review and comment. In contrast to the modeling work, local review is a subjective process whereby local entities are given an opportunity to review the model outputs and suggest adjustments. For this, local reviewers use their own expertise, experience, and knowledge along with substantiating information such as adopted comprehensive plans and known development activity. An important point to note is that both the objective (modeling) and subjective (local review) processes represent possible outcomes of future development activity and each are subject to the issues associated with long-term forecasting. As the final effort in the process, NCTCOG staff assessed input submitted by local reviewers along with other items that NCTCOG tracks. The final internal review by NCTCOG was necessary to: •

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Verify that input from the local reviewers represents a development pattern that is either just as or more likely than the one proposed by the model. This too is a subjective process. NCTCOG staff use current ortho photography, appraisal district data, development activity, land use information, and other data to make the determination. Reconcile conflicting input from multiple entities reviewing the same area. TSZs do not necessarily respect any particular political boundaries, other than counties, and therefore often span multiple jurisdictions. Again, NCTCOG staff use current ortho photography, appraisal district data, development activity, land use information, and other data to make a determination. Maintain the year 2005 base data. This is necessary because the 2005 data served as a direct input in the modeling process. In some cases, this restriction results in discrepancies between the TSZ-level figures and figures for the same areas from other sources. Ensure that the market-level figures are respected. The market totals are the approved NCTCOG forecasts and as such could not be violated as a result of local review. Because of this constraint, some valid comments submitted through the local review process could not be accommodated entirely. Determine the final allocation for each TSZ. This takes into consideration the four preceding items. An important point to note is that the final TSZ-level figures are not approved by the NCTCOG Executive Board and therefore not official in the same sense as the market-level figures.

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NCTCOG Demographic Forecast Overview Population The G-LUM models output households. Household population 4 is estimated separately using another process developed by NCTCOG. The critical factor in calculation of household population is the average number of persons in a household. Household sizes vary by area and changes in household sizes do occur over time. This was taken into consideration in the development of the household population figures.

Employment Employment in the Demographic Forecast is a projection of the number of jobs, not necessarily the number of workers. The G-LUM models take into account the fact that workers can have more than one job and that there will be some unemployment.

Select Cities Published city-level figures are the result of aggregations of Traffic Survey Zone (TSZ) allocations approximated to city boundaries. None of the models used in the demographic forecasting process consider city boundaries. In addition, TSZs do not cede to city boundaries. To derive the figures, each selected city was assigned a share of a TSZ’s allocation based on proportion of area. The assumption here is that the allocations of household population and employment are dispersed evenly across the TSZ, which might or might not be accurate. All figures are for city boundaries as delineated by the U.S. Census Bureau for tabulation of the 2010 Census data and do not take into account future annexations or extra-territorial jurisdiction. For example, over the last decade the City of Fort Worth has experienced substantial growth, much of which has been in areas annexed over the decade. A similar type of activity occurring in the future is not captured by the figures shown here. “Select cities” include incorporated places with a population of at least 30,000 based on the official count from the 2010 Census. Household population excludes persons living in group quarters such as dormitories, nursing homes, and jails. City-level aggregations are provided merely as an informational item and are likely to differ from any projections produced by or specifically for an individual city.

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Household population excludes people living in group quarters such as dormitories, nursing homes, and correctional facilities. 5

NCTCOG Demographic Forecast Overview County Forecasts County-level forecasts can be derived by summing all the district-level forecasts within a county. Since forecast districts nest precisely to counties, the calculation is relatively straight-forward. The G-LUM models operate at the district level and each district in the region is considered by the models in relation to all other districts in the region. Therefore, G-LUM does not produce a county-level forecast. However, summing the district forecasts to counties can provide a reasonable measure of households and employment predicted by the G-LUM model for each county.

Additional Data NCTCOG has several ongoing programs that support the demographic forecast and other work including census data support, development monitoring, population and housing estimates, small-area estimates, and land use inventory.

Acknowledgement The 2040 Forecast is the result of a multi-year effort involving many hours of diligent effort not only on the part of NCTCOG staff but on the part of many others as well. NCTCOG wishes to express its great appreciation to the many local jurisdictions and organizations that shared valuable insight and provided support and patience during this forecasting process. The NCTCOG Transportation Department performed the modeling work and some data collection. The NCTCOG Research and Information Services Department provided data collection and facilitated the local review.

Disclaimer These data were developed for regional planning activities and have not been evaluated for other uses. The North Central Texas Council of Governments makes no warranty, express or implied, including warranties of merchantability and fitness for a particular purpose. Responsibility for the use of these data lies solely with the user.

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