DEMOGRAPHIC ESTIMATES Technical Memorandum No. 3 Transportation Plan Update 2040
Travel Demand Model Development Update
Prepared by
in collaboration with
Neel-Schaffer, Inc.
Louisiana Department of Transportation and Development
July, 2015 Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______T A B L E O F C O N T E N T S
DEMOGRAPHIC ESTIMATES 1.0 Introduction 2.0 Executive Summary 3.0 Four Demographic Measurements 3.1 Population and Dwelling Unit Methodology 3.2 Employment and School Methodology 3.3 Overall Population Estimates 3.4 Demographic Maps 3.5 MPO Planning Area Population By Parish 3.6 MPO Planning Area Housing Units By Parish 3.7 MPO Planning Area Workers by Parish 3.8 MPO Planning Area School Age Attendance by Parish 3.9 Population Density 3.10 Patterns of Growth 3.11 Patterns of Growth 3.12 Daily Flow and Delay
APPENDIX 1: FORECAST METHODOLOGY REPORT 1.0 Introduction 2.0 Control Totals For Population Projections 2.1 Adjustments to Reflect Study Area 2.2 State of Louisiana Population Projections 2.3 Historical Trends 2.4 Woods & Poole Projections 2.5 Study Area Projection Totals 3.0 Cohort Component Procedure 3.1 Survival Rates 3.2 Birth Rates 3.3 Exceptions to The Survival And Birth Rates 3.4 Migration Component 3.5 Combining Cohort Component Parts 4.0 New Dwelling Units 4.1 Estimation of New Dwelling Units 4.2 New Dwelling Unit Methodology Applied to TAZs 4.3 Modifications to Dwelling Unit Calculations 4.4 Land Available for Residential Development 4.5 Land Availability Formulas 4.6 Transportation Variable 4.7 Proximity to Growth Areas 4.8 Examples of Transportation And Proximity Variable Applied to TAZs 5.0 Occupied And Vacant Dwelling Units 6.0 Conclusions
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______C H A R T S, T A B L E S, & M A P S
DEMOGRAPHIC ESTIMATES Map 1-0 Acadiana Planning Area, Parishes and Municipalities Map 2-0 Population Change from 2010 to 2040 Table and Chart 3.3 Population Count in 2010 and Estimates by Ten Year Intervals Table and Chart 3.5 Population Count in 2010 and Estimates by Ten Year Intervals Table and Chart 3.6 Housing Unit (HU) Count in 2010 and Estimates by Ten Year … Table and Chart 3.7 Worker Count in 2010 and Estimates by Ten Year Intervals Table 3.8-A School Age Attendance Count in 2010 and Estimates by Ten Year Intervals Table 3.8-B Percent of Student Population to the Total Population, And Number … Table 3.9-A Persons per Acre as Existing in 2010 and Projected in 2040 Table 3.9-B-1 Persons per Acre as Existing in 2010 and Projected in 2040 Table 3.9-B-2 Persons per Acre as Existing in 2010 and Projected in 2040 Table 3.9-B-3 Sub-Regions, Persons per Acre as Existing in 2010 and Projected in 2040
APPENDIX 1: FORECAST METHODOLOGY REPORT Table 2-1 Adjusting Acadia Parish Population Totals Table 2-2 Historical Trends Forecast for Study Area Table 2-3 Woods & Poole Forecasts for Study Area Table 2-5 Comparison of Historical, Woods & Poole, and Actual Projections Table 3-1 Female Survival Rates Table 3-2 Male Survival Rates Table 3-3 Age Structure of In-Migrants, In-migration Rate Table 3-4 Age Structure of Out-Migrants Out-migration Rate Table 3-5 Example of Survival, Fertility, and Migration Combined Table 4-1 Acadia Parish Example – New Dwelling Units 2020 Table 4-2 Lafayette Parish Examples – New Dwelling Units 2020 Table 4-3 Adjustments to New Dwelling Units – 2030 Projection
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______1.0 Introduction
Urban transportation planning has two equally important components:
-1- Engineering estimates of the capacity and cost of building roadways
-2- Demographic Estimates of the amount of persons who will use these roadways.
Tech Memo 3 forecasts the number of people, households, school children, and businesses, each of which generate significant traffic. Appendix 1 provides technical details on the methods.
Elected officials and their technical advisors use this information to select which roads to build as shown in Figure 1: Acadiana Metropolitan Planning Area
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______2.0 Executive Summary
Robust, sustained growth is expected in the Acadiana Metropolitan Area Study Region through the year 2040. The region’s population is projected to increase by 148,000 new residents (44 %) from 2010 to 2040. That population is greater than the 2014 population of the City of Lafayette. The bar chart below illustrates these increases with four key variables.
In map on the following page, the red -- yellow -- blue spectrum illustrates the least to most population change. Each of the ten colors show ten percent of the total number of person or household or other group being measured; that is to say, each color is a 10% quantile representing one-tenth of the total being measured. This population will fill a vast area of 334 square miles ranging from Duson to Loreauville and Sunset to Maurice as well as all points in between. This includes the City of Lafayette and all of the area within the parish. Significant parts of Iberia and St. Martin are included along with adjoining areas of Acadia, Vermilion, and St. Landry.
Within each of these municipalities and unincorporated areas, 991 neighborhoods are mapped and studied. These neighborhoods are technically known as a Traffic Analysis Zones (TAZs), each of which is bounded by a roadway, a stream or a railroad.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.0 Four Demographic Measurements
Four measurements are used to predict the amount of traffic in this planning area: population, households, workers, and schools.
Each of these four measurements is measured and counted many different ways to improve the accuracy of the traffic estimate. For example, a TAZ located in a residential area in close proximity to a school and a retail area will, in general, generate a different amount of traffic than a TAZ located in a more rural area without adjacent businesses or schools. 3.1 Population and Dwelling Unit Methodology
The demographic estimates are the results of a series of factors. The population of each TAZ is aged to determine the expected number of deaths each decade. Birth rates relevant to each TAZ are applied. In and out migration and the ages of those migrants are estimated by viewing past trends. Past growth in number of dwelling units is analyzed and actual growth in dwelling units through 2013 researched. Assumptions are made regarding expected new housing units and the associated number of migrants expected. Areas of very recent growth are assumed likely to continue growing if available land for development exists. Growth is deemed more likely adjacent to areas already developed, with utilities and infrastructure. Growth is assumed more likely in accessible areas, areas with transportation links – and much less likely in environmentally sensitive areas, like flood zones. 3.2 Employment and School Methodology
Employment is projected separately for two distinct employment sectors, using different methodologies.
Retail employment growth is directly related to population growth. Regions of greatest population growth can expect significant employment growth. It is assumed, however, that retail employment in all parts of the study area will grow at least modestly, even with very little or no population growth in the immediate area. All parts of the study area should benefit from the overall population growth.
Non-retail employment does not directly depend on the population growth in the immediate area, and thus is more tied to the overall growth of the region. Most jobs are expected to grow at approximately the same rate as the population in the study area. Several specific industry categories, such as finance, medical, government and computer elated services are expected to grow slightly faster than the rate of population growth.
School attendance is driven solely by the population projections. Thus, the school attendance increases results in education employment.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.3 Overall Population Estimates
Table 3.3 Acadiana Metropolitan Planning Organization Population Count in 2010 and Estimates by Ten Year Intervals YEAR 2010 2020 2030 2040 30 YEAR 30 YEAR GROWTH GROWTH RATE
Population 338,325 389,328 434,015 486,878 148,553 43.9%
Dwelling Unit 140,714 157,809 173,305 186,991 46,277 24.7%
Tot Workers 167,209 203,498 227,743 255,986 88,777 53.1%
School Age 88,857 96,573 109,825 126,568 37,711 42.4%
As can be seen in the table above and graph below, the growth is robust in a state with shrinking populations within a southern region undergoing steady urbanization. Four massive hurricanes over a period three years have shifted populations movements along the Gulf of Mexico: Katrina – August, 2005; Rita – September 2005; Gustav – August, 2008 and Ike – September 2008. The City of Lafayette has been spared severe hurricane winds over the past fifty years.1 As a result, insurance companies did not raise wind coverage rates nor the National Flood Insurance Program flood protection rates increase as dramatically as areas south of Louisiana Highway 14 in adjoining parishes.
Other factors effecting growth have been increased oil and gas production related to fracking, which is serviced worldwide by petroleum service companies headquartered in
1 Twenty-two named hurricanes have impacted Louisiana since Hurricane Audrey in 1956. Only Hurricanes Danny in 1985 and Andrew in 1992 have a path that was near the most populous city of Lafayette with hurricane force winds approaching 75 mph. See https://en.wikipedia.org/wiki/List_of_United_States_hurricanes#Louisiana.
The Parish has fared less well in terms of rainfall and flooding: Hurricanes Hilda (1964), Juan (1985), Frances (1998), Allison (2001) Rita (2005) and Gustav (2008) each rained over 12 inches in Lafayette Parish. See http://www.srh.noaa.gov/images/lch/tropical/lahurricanehistory.pdf
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______the region. Many of these companies are located along US Highway 90 connecting the City of Lafayette to the City of New Iberia, both of which are the major population centers in the planning area.
The oil bust in the 1980’s resulted in a diversification of the economy in the Parish of Lafayette away from petroleum, although this sector remains strong.
The University of Louisiana at Lafayette (ULL) has a long tradition of strong computer science programs since the 1950’s which resulted in many local residents ready of the digitalization of government, education, commerce and industry in the 1990’s and beyond into the Twenty-First Century. The education investment created a favorable environment for the Fiber to Home Program by Lafayette Utilities System, a public utility wholly owned by Lafayette Government investing over $100 million in high speed internet, video, and phone services. This has led to location of software developers and digitalization of entertainment industries in Lafayette.
Medical services also underwent concurrent growth from the 1980’s onward leading to the location and expansion of regional medical centers at Lafayette General, Lourdes Hospital, and Regional Medical Center of Acadiana. Additional specialty hospitals like Women and Children’s Hospital and the Cardiovascular Institute of the South have driven growth as well. The medical workforce alone today is more than 20,000 workers.
Other significant components of the local economy are2:
Construction—New concepts in residential development like the New Urbanist River Ranch, combined with regulatory innovations by local government, the university and private business have propelled the construction industry forward in commercial activity. Construction activity in 2013 reached over $281 million.
Retail Trade/Leisure & Hospitality/Entertainment—Nearly one quarter of the Parish of Lafayette’s sale tax revenues is brought in by spenders from outside of the parish’s borders. People from all over Acadiana travel here for many reasons, including shopping, entertainment, recreation, dining, services and business. The population in Lafayette’s trade market is in excess of 600,000 people and over 1 million tourists visit this area every year.
Finance—The financial industry within Lafayette Parish is comprised of 25 locally-owned and nationally operated banking institutions, with an estimated $5,620,021,000 in deposits as of June 2013. They provide services ranging from simple savings and checking accounts to complex commercial investments. Thirteen credit unions have also been established within the Parish, with estimated total assets over $384 million in 2013.
Manufacturing—The innovation of local manufacturers has resulted in the transformation of traditionally low technology industries into modern high-tech environments through state-of- the-art computers, intelligent manufacturing systems, robots and automation. Thriving
2 http://lafayette.org/uploads/LafayetteLAEconomicProfile91914.pdf August 2, 2015 Page 8 of 51
Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______manufacturing businesses in Lafayette can be found across sectors including jewelry, oil and gas, marine, food production, and specialty metals.
Transportation/Distribution—Located at the crossroads of Interstates 10 and 49, Lafayette’s strategic location has contributed to the viability of the transportation/distribution industry. Cargo can be delivered via the Intracoastal Waterway, and the proximity of Lafayette to the Gulf of Mexico makes deliveries and exports by sea feasible.
3.4 Demographic Tables and Maps
In addition to this report, a set of tables are available entitled, 2040 Demographic Tables, Acadiana Metropolitan Planning Organization. These tables provide the base figures for the analysis presented in the report and on the maps. These figures are given for each of the nearly 1000 TAZ’s.
A set of maps illustrate base figures in a more understandable form. Each map is discussed in turn as it appears in the report.
Map 01 Ratio of Population 2040 to 2010 shown with Road Names and TAZs Map 02 TAZ Numbering System Map 03 Population Change in Numbers of Persons 2010 to 2040 Map 04 Population Change in Percent of Persons 2010 to 2040 Map 05 Persons per acre 2010 Map 06 Persons per acre 2040 Map 07 Circles with a Radius of One Mile, Persons per Square Mile 2010 and 2040 Map 08 Change in Numbers of Households 2010 to 2040 Map 09 Percent Change in Numbers of Households 2010 to 2040 Map 10 Households per Acre 2010 Map 11 Households per Acre 2040 Map 12 Circles with a Radius of One Mile, Households per Square Mile 2010 and 2040 Map 13 Persons per Household 2010 Map 14 Change in Total of All Workers 2010 to 2040 Map 15 Percent Change in Total of All Workers 2010 to 2040 Map 16 Change in Retail Workers 2010 to 2040 Map 17 Change in the Percent of Retail Workers 2010 to 2040 Map 18 School Attendance 2010 Map 19 School Attendance 2040 Map 20 Regions, Persons per Acre 2010 and 2040 Map 21 Regions and Sub-Regions, Persons per Acre 2010 and 2040 Map 22 Patterns of Growth and Population Density 2010 to 2040 Map 23 Households Increased due to Proximity to Growth 2030 and 2040 Map 24 Ethnicity, Gender and Age, 2010 Map 25 Circles with a Radius of One Mile, Ethnicity, Gender and Age, 2010 Map 26 Daily Traffic Flow and Delay
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.5 MPO Planning Area Population by Parish
Maps 01 and 02 are for reference showing the roadways and the numbering system used to identify Traffic Analysis Zones (TAZs).
Map 03 shows the number of the persons increasing for each TAZ while Map 04 shows the percentage changing in each TAZ. The maps show that the urban core of the City of Lafayette is losing population while the surrounding areas near the municipalities of Carencro, Scott, Youngsville and Broussard are gaining in population. Map 05, Persons per Acre in 2010, shows a clustering of dense blue areas near the center of the City of Lafayette and a low density ring show in red and yellow. Map 06, Persons per Acre in 2040 shows the increased density within the City of Lafayette spreading southward toward Youngsville and Broussard and northward toward Carencro.
Map 07 has two maps showing the population density for 2010 and 2040. Unlike the other maps using TAZs, these two maps show density with circles within an area of a square mile. As these circles overlap, the color changes from gray to orange and then from yellow, light blue, and then dark blue with increasing density of population along this spectrum of colors.
In 2010, three density centers are apparent. The northernmost is located at the intersection of Vermilion and Jefferson Streets in downtown Lafayette. The southernmost center is located near the geographic center of the parish at the intersection of Marie Antoinette and Congress Streets near Lafayette High School. 3 The third density center is located in downtown New Iberia at the intersection of Center and East Pershing Streets.
In 2040, two additional clusters of increased density appear at the intersection of Verot School Road (LA Hwy 339) and Camellia Boulevard and at the intersection of Milton Avenue (La Hwy 92) and the Youngsville Highway near Youngsville.
As shown by the Table 3.5 and its chart below, and the map on page 1, Lafayette Parish is wholly contained within the Lafayette MPO Planning Area, comprising nearly two thirds of the planning area population. The overall rate of growth for the planning are and the parish of Lafayette show parallel lines on the graph indicating nearly the same rates of growth. However, the remaining portions of adjoining parishes have much flatter and lower trend lines indicating less growth at a lower rate of increase.
3 The geographic center is calculated by averaging the sum of the X and Y coordinates of the centroid of each TAZ and then plotting the resulting average X and Y coordinate. August 2, 2015 Page 10 of 51
Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 3.5 Acadiana Metropolitan Planning Organization Population Count in 2010 and Estimates by Ten Year Intervals PARISH YEAR GROWTH
2010 2020 2030 2040 30 YEAR 30 YEAR GROWTH GROWTH RATE
Acadia 2,659 3,452 4,283 5,297 2,638 99%
Iberia 60,368 67,273 73,983 82,196 21,828 36%
Lafayette 221,524 255,231 282,500 314,060 92,536 41%
St Landry 7,690 9,349 11,200 13,613 5,923 77%
St Martin 41,233 47,656 54,026 61,544 20,321 49%
Vermilion 4,851 6,366 8,024 10,168 5,317 1.10%
TOTAL 338,325 389,328 434,015 486,878 148,553 38.3%
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
3.6 MPO Planning Area Housing Units by Parish
The Table 3.6 and it chart below indicate that the household size in the study area is expected to grow from 2.40 persons to 2.60 persons. The growth in household size is estimated by an analysis of race, age and gender combinations in growing neighborhoods. These neighborhoods have more children per household; these children will increase the school population.
The overall rate of growth in the chart is mirrored by Lafayette Parish. However, Iberia and St. Martin Parishes have lower and flatter slopes. This graphic pattern means lower and slower growth rates. The remaining portions of adjoining parishes are very low and flat in growth rates.
Map 08, Change in Numbers of Households, and Map 09, Percent Changes in Number of Households, show the same pattern as shown in Section 3.4 MPO Planning Area Population by Parish. The urban core is losing households while surrounding areas are gaining households. Similarly, Map 10, Households per Acre (in) 2010, and Map 11, Households per Acre (in) 2040, show similar patterns as shown in above in regards to population density. Population density remains steady in the urban core and extending southward and northward in 2040.
Map 12 has two maps showing the population density for 2010 and 2040. Unlike the other maps using TAZs, these two maps show density with circles, each circle having an area of one square mile. As these circles overlap, the color changes from gray to orange and then from yellow, light blue, and then dark blue indicating a continuum of increasing population density.
The household clusters mirror people clusters as discussed above on the previous page for Map 07. The differences between the household and population clusters are based on differences in the number of persons per household.
Map 13, Persons per Household in 2010, shows that areas where population is increasing are also the same areas where the number of persons per household is also increasing.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 3.6 Acadiana Metropolitan Planning Organization Housing Unit (HU) Count in 2010 and Estimates by Ten Year Intervals PARISH YEAR GROWTH RATE
2010 2020 2030 2040 NUMBER PERCENT(%)
Acadia 1,052 1,329 1,626 1,928 876 83
Iberia 24,394 26,384 28,371 30,115 5,721 23
Lafayette 93,621 105,448 115,544 124,163 30,542 33
St Landry 3,255 3,788 4,362 4,971 1,716 53
St Martin 16,488 18,482 20,496 22,351 5,863 36
Vermilion 1,904 2,378 2,906 3,463 1,559 82
TOTAL 140,714 157,809 173,305 186,991 46,277 33
AVG HU SIZE 2.40 2.47 2.50 2.60 0.20
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.7 MPO Planning Area Workers by Parish
As shown in the Table 3.7 and its chart below, the number of workers is estimated to increase by 54% in the parish of Lafayette with a household increase of 33% during the same period. Beyond being the most populous, Lafayette Parish has the most number of workers. The relative increase of workers to the number of households indicates that the number of workers per household is increasing. The relative increase means that more adult, two wage earner households are anticipated to reside in the area or additional workers are commuting into the area for work.
A comparison of the dramatic rate of change in the number of workers is shown in the steepness of curve slope for total employment and Lafayette Parish Employment.
Map 14, Change in Total All Workers, and Map 15, Percent Change in Total Workers, shows that workers are concentrated in the core of Lafayette Parish. The distribution of employment is the reverse of residential pattern. Workers work in the center of the planning area. Residential households are distributed in the outlying areas around the employment center.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 3.7 Acadiana Metropolitan Planning Organization Worker Count in 2010 and Estimates by Ten Year Intervals PARISH YEAR GROWTH RATE
2010 2020 2030 2040 NUMBER PERCENT (%)
Acadia 447 582 659 748 301 67
Iberia 27,173 31,900 35,475 39,597 12,424 46
Lafayette 123,761 151,803 169,811 190,681 66,920 54
St Landry 1,358 1,698 1,944 2,252 894 66
St Martin 13,610 16,359 18,537 21,196 7,586 56
Vermilion 860 1,156 1,316 1,511 651 76
TOTAL 167,209 203,498 227,743 255,986 88,777 53
AVG WORKER/HU 1.19 1.29 1.31 1.37 0.18 15.2
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.8 MPO Planning Area School Age Attendance by Parish
As shown on the Table 3.8-A and its chart below, there are more student populations in the outlying areas than in the urban core. The number of students in these outlying areas is indicative of an out migration from the urban core to suburban neighborhoods. In addition, these suburban families have larger family sizes than those in the center of the city.
Map 18, School Attendance in 2010 shows the location of current schools while Map 19, School Attendance in 2040, shows the location of the current schools plus the additional schools needed to meet the demand for new students. These new schools are shown at the center of the TAZ of where the demand for schools is projected. The actual location of these news schools, of course, is subject to review in other demographic studies as well as by school boards. The map shows, as such, only the general location of the predicated location of new schools.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 3.8 -A Acadiana Metropolitan Planning Organization School Age Attendance Count in 2010 and Estimates by Ten Year Intervals PARISH YEAR GROWTH RATE
2010 2020 2030 2040 NUMBER PERCENT
Acadia 533 586 727 1,000 467 88
Iberia 14,101 14,663 17,483 20,207 6,106 43
Lafayette 61,843 67,009 75,038 84,981 23,138 37
St Landry 1,968 2,421 2,950 3,603 1,635 83
St Martin 9,059 10,268 11,839 14,179 5,120 57
Vermilion 1,353 1,626 1,789 2,598 1,245 92
TOTAL 88,857 96,573 109,825 126,568 37,711 42
STUDENT/HU 1.58 1.63 1.58 1.48
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______The table below shows three kinds of figures:
1.. The percentage of the TAZs area where schools are located to the area of the parish within the planning area.
2.. The percentage of the student population by parish to the total parish population within the planning area.
3.. The number of new schools projected to be needed within the planning area.
Table 3.8-B Acadiana Metropolitan Planning Organization Percentage of Parish Planning Area Effected by School Locations, Percent of Student Population to the Total Population, And Number of New Schools Projected to be Built by 2040 Parish Area Population Percent New
Percent 2010 2020 2030 2040 Schools
Acadia 25.8 20.0 17.0 17.0 18.9 1
Iberia 15.8 23.4 21.8 23.6 24.6 6
Lafayette 13.6 27.9 26.3 26.6 27.1 15
St Landry 23.6 25.6 25.9 26.3 26.5 1
St Martin 13.4 22.0 21.5 21.9 23.0 5
Vermilion 11.1 27.9 25.5 22.3 25.5 0
TOTAL 21.1 26.3 24.8 25.3 26.0 28
Schools directly affect a large percentage of the population and a large percentage of the planning area; for
1. About one-fourth of the population attends schools; and
2. About one-fifth of the area is directly effected by a nearby school.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.9 Population Density
The next two maps show the density of population by region and sub-region:
Map 20 describes the number of person per acre in 2010 and 2040 for the five large regions.
Map 21 describes the number of person per acre in 2010 and 2040 for sub-regions of each of these five large regions.
As can be seen on Map 20, six regions divide the MPO Planning area. The bluest areas are the most dense in terms of persons per acre, the tan and green regions less so, and the red areas are the least dense. The ranking of densities from the most dense to the least dense in 2010 are shown in Table 3.8-A. The ranking remains the same in 2010 and 2040.
Table 3.9 - A Acadiana Metropolitan Planning Organization Regions Persons per Acre as Existing in 2010 and Projected in 2040 REGIONS PERSONS PER ACRE
2010 2040
Central Lafayette 3.63 3.87
South Region 1.23 2.07
Iberia Parish 0.69 0.96
West Region 0.69 1.08
North Region 0.62 1.02
St. Martin Parish 0.37 0.55
TOTAL 0.69 1.08
Map 21 shows the sub-regions for each of the regions. As in Map 20, the bluest areas are the most dense, the tan and green regions less so, and the red areas are the least dense. Now however, the density of each sub-region is shown independent of its region. The distribution of high density sub-regions can be explained by the settlement patterns along transportation routes. By the year 2040, the sub-regions along the Bayou Vermilion are nearly all in various shades blue indicating the highest density. These subregions along Bayou Vermilion were the first settled in the colonial era prior to the annexation of the state into the United States in 1803. Three other high density blue areas also have an historical explanation. The first blue area is along the Southern Pacific Railroad, built in the 1880’s. The second blue area is also along a transportation route, US Highway 90 built in 1930’s. The third area is along two
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______interstates: Interstate 10 built in the 1960’s traversing from East to West and Interstate 49 constructed in the 1980’s traveling from South to North.
Table 3.8-B on the next page is divided into two parts on the following pages. Each table shows the existing values in 2010 and then the project values for 2040. The first table shows region and sub-region values for Central Lafayette and Iberia Parish The second table list figures from the North and South Regions and their sub-regions. The final tables show the St. Martin and West Region.
Table 3.9- B-1 Acadiana Metropolitan Planning Organization Sub-Regions Persons per Acre as Existing in 2010 and Projected in 2040 REGIONS SUB-REGIONS PERSONS PER ACRE
2010 2040
Central Lafayette Central Business District 3.42 3.48
Central Lafayette Lafayette East 2.06 2.39
Central Lafayette Lafayette Northwest 4.40 4.84
Central Lafayette Lafayette South 5.06 4.96
SUBTOTAL 3.63 3.87
Iberia Parish Central New Iberia 6.07 7.22
Iberia Parish Iberia Northwest 0.36 0.59
Iberia Parish New Iberia Peninsula 3.69 4.17
Iberia Parish New Iberia South 0.37 0.50
Iberia Parish New Iberia Southeast 0.46 0.72
Iberia Parish North Iberia - Central South 4.16 4.92
Iberia Parish North New Iberia – Loreauville 0.44 0.71
SUBTOTAL 0.69 0.96
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 3.9- B-2 Acadiana Metropolitan Planning Organization Sub-Regions Persons per Acre as Existing in 2010 and Projected in 2040
North Region Acadia Parish 0.24 0.47
North Region North – Carencro 1.21 2.00
North Region North – Midlands 0.96 1.80
North Region North – Northeast 0.75 1.00
North Region North – Northwest 0.50 0.84
North Region St. Landry Parish 0.38 0.68
SUBTOTAL 0.62 1.02
South Region Airport 0.28 0.43
South Region Broussard 0.75 1.07
South Region South - Far South 0.29 0.92
South Region South - Kaliste Saloom 3.47 4.57
South Region South – Milton 0.84 1.68
South Region South - Vermilion Parish 3.18 3.93
South Region South – Youngsville 1.54 3.18
SUBTOTAL 1.23 2.07
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 3.9- B-3 Acadiana Metropolitan Planning Organization Sub-Regions Persons per Acre as Existing in 2010 and Projected in 2040 REGION SUB-REGION PERSONS PER ACRE
2010 2040
St. Martin Parish Breaux Bridge 1.42 2.02
St. Martin Parish Parks 0.28 0.49
St. Martin Parish St Martin North 0.46 0.75
St. Martin Parish St Martinville 0.92 1.03
St. Martin Parish St. Martin East – Henderson 0.51 0.83
St. Martin Parish St. Martin South 0.14 0.23
St. Martin Parish St. Martin West 0.12 0.19
SUBTOTAL 0.37 0.55
West Region Vermilion Parish 0.27 0.56
West Region West - Congress/Johnston 0.93 1.40
West Region West – Duson 0.35 0.60
West Region West - Far West 0.19 0.35
West Region West - Johnston/River 2.58 3.80
West Region West – Scott 1.66 2.44
SUBTOTAL 0.69 1.08
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.10 Patterns of Growth
Map 22 is titled Patterns of Patterns of Growth and Population Density. There are five different maps used to show these patterns.
The largest map shows the percentage to the nearest 10 percent (quantile) for the years 2010, 2020, and 2030. The gray area has less than 60% of land available for development and thus indicate where development has already begun.
The remaining colors indicate where development has yet to begin:
Blue = 70% to 79% of land is available for development in 2010
Yellow = 80% to 89% of land is available for development in 2010;
Green = 90% -100% of land is available for development in 2010;
The blue areas are ones that are predicted to develop first followed by the yellow and then green areas.
The green areas grow very slowly; but the blue and yellow areas are places where once development starts, then development is expected to proceed rapidly.
The numbers in each TAZ show different development patterns for the years 2010, 2020, and 2040 as explained in the notes in the lower left hand corner of the map.
The four remaining maps show the numbers of persons per acre as a measure of population density in 2010, 2020, 2030, and 2040. The 2010 maps depict the actual number of persons counted during the census. The other three maps show estimates of persons based on a demographic model that measures and projects population based in a series of factors (discussed in Section 3.1 Population and Dwelling Unit Methodology.
These maps compare both the social geography as well as the physical geography of the planning area. The larger map shows where population growth is projected based on physical features, which is the availability of land for development. The available land is shown as in various quantities: blue (70% to 79%) and to a lesser extent in yellow (80% to 89%).
The smaller four maps show social geography, which is how the land is being utilized by people. The blue areas has the most population density spreading from the center of the parish southward toward Youngsville. To a lesser extent on the north end of Lafayette Parish, the blue population density also extends toward Carencro.
The overall pattern between land availability and population density is that population density is projected to spread southward.
Map 23 is titled Households Increased due to Proximity to Growth 2030 and 2040. The map show the predicted increase in the number of households in TAZ’s that are near growth areas for the years 2030 and 2040. Studies of growth patterns indicate that TAZs near growth will increase due to proximity in addition to demographic increases.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.11 Patterns of Growth
Map 24 illustrates a TAZ theme of population density for the large map and then TAZ themes for Percent Non-White Population, Percent Hispanic, Percent Children ages from birth to 17 and Percent Women of Child Bearing Age. Two ethnic maps are used to address Title VI Anti-Discrimination Requirements of the 1964 Civil Rights Bill as amended. The Non-White population is large and concentrated north of the former Southern Pacific Railroad (now is still operative with many names changes). That railroad parallels US Highway 90 from south to New Iberia and then turns directly true west towards Texas. At that point, the railroad parallels US Highway 90 and Interstate 10.
The first map showing percent women of child bearing age and a second map showing per children are used to show the relationship between areas anticipated for growth based on increased birth rates.
Map 25 shows these same variables by population densities per square mile of Non-Whites, Hispanic, Children ages from birth to 17 and Women of Child Bearing Age.
The larger number of Non-White Populations to Hispanic Populations is shown by comparing the color densities scaled the same for all maps. The relationships of these variables to children and woman are shown by comparing the two other side-by-side maps. 3.12 Daily Flow and Delay
The report has largely focused on demographic patterns without discussing population impact on traffic. Map 26 shows how the distribution of population utilize the transportation network creating daily flows of traffic.
Traffic delay are characterized by slower speeds, longer trip times, and increased queuing. Each of these criteria are the indicators of traffic demand that is greater than the available capacity of the road network. These conditions are exacerbated by various land use and infrastructure investment decisions that do not promote the most efficient use of the transportation network. Delay is calculated by determining the difference between the estimated travel time under actual (often congested) conditions and under uncongested conditions.4
Map 26 has five maps, with largest maps to the left illustrating the number of daily trips. Roadways are mapped using lines that trend from red to blue. The least number of trips is shown in red while the most number of trips is shown in blue. The blue roads are one in which drivers take from the outlying red road areas into the center of Lafayette Parish. These outlying areas are growth areas, which have growing populations. The center of the parish has declining populations, but more employment. Trips to and from work and home explain the pattern.
4 http://www.floridatransportationindicators.org/index.php?chart=14 August 2, 2015 Page 24 of 51
Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______The four smaller maps depict delay. The bluer the area, the more delay while orange areas have less delay. Yellow and green are midway between these two extremes.
The current 2010 map shows significant delay along the eastern portions of Interstate 10.
The 2020 maps shows slightly less delay in the same area along eastern Interstate 10. However, delay is building toward Duson on the western end of Interstate 10 and along Interstate 49 from Carencro northward.
By 2030, we see an increase in delay of these previous areas, but also toward the south along US Highway 90 near northwest of New Iberia.
We see that in 2040 all of these blue area intensity indicating widespread delay along major roadway traveling from outlying areas into Lafayette Parish.
This pattern reinforces the view that these outlying areas are growth areas, with populatoins traveling into the center of Lafayette Parish and residing in outlying areas.
As stated above, trips to and from work and home explain the pattern.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______APPENDIX 1 Forecast Methodology
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______Neel-Schaffer, Inc.
Lafayette MTP 2040 Forecast Methodology Report
Submitted to
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______1.0 INTRODUCTION
Good population projections are the result of having good historic data, a knowledge of current conditions, and an understanding of likely future activities. Based on such information, projections can be an excellent indicator for those concerned with long-range urban planning. Projections can never predict exact behavior with precision. Projections tell us what is most likely to happen given current knowledge. Projections can then be modified to incorporate new knowledge and information as it becomes available.
Population and dwelling unit projections from 2010 to 2020 are done with the goal of maximum accuracy. Increased accuracy is possible as one possesses recent data (2010), updated by current information (2013), and a greater awareness of short-term trends (2013- 2020). Therefore, the methodology for the 2020 projections differs slightly from the long- range projections and takes into account recent residential construction in Lafayette Parish (2010-2013), approved transportation improvements, very recent growth trends, and population aging (births and deaths). Population and dwelling unit projections for 2030 and 2040 include population aging, impacts from expected longer range transportation projects, past growth trends (especially 2000-2010), amount of available residential land and proximity to developed residential areas.
All population and dwelling unit projections are done at the Traffic Analysis Zone (TAZ) level. Each TAZ is projected independently from all others. Thus TAZs can be grouped together in any way which facilitates an improved understand of the data. TAZs are grouped geographically to check on regional and directional bias, and functionally grouped to unite TAZs with similar characteristics.
While the methodology contains numerous formulas and represents a quantitative approach to the problem, it should be remembered that formulas are simply an amalgam of subjective decisions. Formulas make it easier to replicate the process and to change assumptions, but one still must decide which variables to include and the relative weight of each variable. Therefore, it is appropriate to present an overview of basic guiding principles or assumptions used in formulating the methodology.
Unless given knowledge to the contrary, past trends are likely to continue.
Life cycle stages continue and life cycle events are associated with both population and dwelling unit change (age-specific events such as leaving home, marriage, births, retirement, death).
Lack of available land limits residential construction. Availability of large tracts of land is more conducive for the development of major subdivisions.
Land immediately adjacent to major transportation arteries are more likely to have commercial or industrial uses than single family residential use. But the presence of such arteries encourages residential growth in the region.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______Population growth can generate new commercial activity. New commercial activity can also encourage residential growth (multifamily dwellings adjacent and single family dwellings in the region).
Areas within the flood plain are less likely to be developed. Areas with significant wetlands are very unlikely to have extensive residential development.
Growth is most likely to occur in areas adjacent to developed areas. Infrastructure is more readily available and urban amenities and services more accessible.
Funding will continue from many levels of government to target development (and redevelopment) within currently served areas. This reduces new utility and other infrastructure costs and can concentrate and focus basic utility and government services.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______2.0 CONTROL TOTALS FOR POPULATION PROJECTIONS
While the population projections are done at the individual TAZ level, it is still realized that the study area summary totals for population and dwelling units must be reasonable and justifiable. Appropriate control totals have been garnered from several sources. In past studies, the State of Louisiana population projections were extremely useful. However, the currently available projections are outdated and of very limited usefulness. Historical trends, at the parish level, provide a good basis for future growth and thus are calculated and included. Professional population projections by the firm Woods & Poole are also utilized. The company is well-known for its population projections at the county (parish) level throughout the United States. It is concluded that the parishes in the study area will most likely grow significantly faster than past historical trends. It is also believed that most parishes will not grow as fast as the optimistic Woods & Poole projections. Almost all of the projections, for all parishes and all decades, fall between these two benchmarks.
2.1 Adjustments to Reflect Study Area
Only Lafayette Parish is included in its entirety. The study area includes only portions of the other four parishes. Therefore, growth rates and population totals must be adjusted to reflect those parts of parishes included in the study area. For St. Martin and Iberia Parishes, the study area comprises over 75% of the parishes and the past growth rates in the study area are very similar to the parishes as a whole. For Acadia, St. Landry and Vermilion Parishes, however, the study area represents only a small portion of each parish, and in each instance, the study area has grown much more rapidly over the last ten (and twenty) years than the remainder of parish. Thus appropriate adjustments need to be made to properly develop expected control totals.
Acadia Parish is presented as an example of how adjustments are made. Similar procedures are used for St. Landry and Vermilion Parishes.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 2-1 Acadiana Metropolitan Planning Organization Adjusting Acadia Parish Population Totals
2000 58,861 2010 61,773 Increase 2000 – 2010 2,912 4.95% increase
Study area population
2000 2,161 2010 2,659 Study area growth 2000-2010 498 23.04% increase
Acadia Parish growth 2000-2010 2,912 Percent of Acadia Parish growth in Study area – 2000 - 2010 17.10% Percent of Acadia Parish growth in Study area – 1990 - 2000 9.39% For calculations: Assume Study area in future will contain approx. 20% of Parish growth.
2.2 State of Louisiana Population Projections
There are a number of issues with current population projections for the MPO planning area. The latest Official State of Louisiana Population Projections updated in 2007 to include impacts of Hurricane Katrina for each parish. The Katrina period held great uncertainty as to the future development of the Gulf Coast. After the 2010 census, the most current data was not used to estimate population growth. As a result, the estimates were not valid. In 2010 the Lafayette Parish population was enumerated at 221,578. In 2030, the State of Louisiana projections for the parish predicted no growth for Lafayette Parish at 221,600. Similar issues were found in other parishes. Therefore, these projections are not found to be useful.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______2.3 Historical Trends
By averaging population growth in the previous three decades, historical trends can be established for each parish. It should be noted that St. Landry Parish shows a decline from 2030 to 2040 – this the result of the Parish’s population decline from 1980 to 2010. The rest of the parishes are all expected to exhibit moderate growth over the next thirty years.
Table 2-2 Acadiana Metropolitan Planning Organization Historical Trends Forecast for Study Area
Acadia Iberia Lafayette St. Landry St Martin Vermilion 2010 Census 2,659 60,368 221,578 7,690 41,233 4,851 Historic 2020 Forecast 3,028 64,395 238,556 8,494 46,642 5,023 Historic 2030 Forecast 3,588 67,801 265,265 8,665 50,787 5,352 Historic 2040 Forecast 4,173 66,910 299,478 8,239 53,894 5,728
2.4 Woods & Poole Projections
The Woods & Poole projections present a very optimistic scenario of population growth for all parishes in the study area. Indeed, Lafayette Parish is forecast to nearly double. These projections do provide a useful benchmark for maximum population growth expectations.
Table 2-3 Acadiana Metropolitan Planning Organization Woods & Poole Forecasts for Study Area
Acadia Iberia Lafayette St. Landry St Martin Vermilion
2010 Census 2,659 60,368 221,578 7,690 41,233 4,851 W&P 2020 Forecast 3,936 67,654 279,340 9,468 49,352 7,113 W&P 2030 Forecast 5,305 75,600 344,092 11,295 58,061 9,592 W&P 2040 Forecast 6,612 83,371 411,073 12,917 66,900 12,162
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______2.5 Study Area Projection Totals
The projections derived, in almost all instances, fall between the historical and Woods & Poole forecasts. St. Landry Parish presents a unique situation, in that the population of the parish declined while the portion of the parish in the study area increased. This makes it difficult to determine the percent of St. Landry Parish’s growth to attribute to the study area. For this study, a value of 30% is utilized.
These control values for each parish were only used as a guide. Each TAZ is independently evaluated and uniform guidelines applied to all TAZs regardless of the parish in which they are located. Working upward from the TAZ level creates population totals consistently between the historical and Woods & Poole forecasts. Thus, moderate and consistent population growth is projected for the entire study area for each decade.
Table 2-5 Acadiana Metropolitan Planning Organization Comparison of Historical, Woods & Poole, and Actual Projections
2020 Acadia Iberia Lafayette St. Landry St. Martin Vermilion Total
2010 2,659 60,368 221,578 7,690 41,233 4,851 338,379 2020 Hist 3,028 64,395 238,556 8,494 46,642 5,469 366,584 2020 W&P 3,936 67,654 279,340 9,468 49,352 7,113 416,863 2020 Proj. 3,452 67,273 255,254 9,349 47,656 6,366 389,350
2030 Acadia Iberia Lafayette St. Landry St. Martin Vermilion Total
2030 Hist 3,588 67,801 265,265 10,853 50,787 6,648 404,942 2030 W&P 5,305 75,600 344,092 11,295 58,061 9,592 503,945 2030 Proj. 4,283 73,983 282,407 11,200 54,026 8,024 433,923
2040 Acadia Iberia Lafayette St. Landry St. Martin Vermilion Total
2040 Hist 4,173 66910 299478 11,501 53594 7,995 443,651 2040 W&P 6,612 83371 411073 12,917 66,900 12,162 593,035
2040 Proj. 5,297 82,196 313,827 13,613 61,544 10,168 486,645
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______3.0 COHORT COMPONENT PROCEDURE
Cohort component methodology involves utilizing appropriate techniques to determine expected births and deaths in a given population over time. This procedure may also be used to help determine migration. This cohort component methodology is used for the all projections, applied individually to each TAZ each decade. 3.1 Survival Rates
Survival rates are calculated from the most recent Louisiana life tables (2000), separately for males and females. Survival rates are calculated in ten-year age intervals and applied individualy to each TAZ. The life table represents 100,000 people all experiencing 2000 mortality rates. For example, with a group of 100,000 males age 0-10, 99,696 would be expected to survive to become 10-20 years old ten years later (a survival rate of .99696). Analogously, of 100,000 males aged 70-80, 48,423 would be expected to survive to become 80-90 years old ten years later (a survival rate of .48423). The male and female survival rates utilized are shown in Tables 5 and 6. The same survival rates are used for all TAZs for all decades.
Table 3-1 Acadiana Metropolitan Planning Organization Female Survival Rates
Age % Surviving 0-10 in 2010
To be 10-20 in 2020 0.99696 10-20 in 2010
To be 20-30 in 2020 0.98929 20-30 in 2010
To be 30-40 in 2020 0.9853 30-40 in 2010
To be 40-50 in 2020 0.97378 40-50 in 2010
To be 50-60 in 2020 0.94389 50-60 in 2010
To be 60-70 in 2020 0.87613 60-70 in 2010
To be 70-80 in 2020 0.73447 70-80 in 2010
To be 80-90 in 2020 0.48423 80+ in 2010
To be 90+ in 2020 0.16396
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 3-2 Acadiana Metropolitan Planning Organization Male Survival Rates
Age % Surviving 0-10 in 2010 To be 10-20 in 2020 0.99696 10-20 in 2010 To be 20-30 in 2020 0.98929 20-30 in 2010 To be 30-40 in 2020 0.9853 30-40 in 2010 To be 40-50 in 2020 0.97378 40-50 in 2010 To be 50-60 in 2020 0.94389 50-60 in 2010 To be 60-70 in 2020 0.87613 60-70 in 2010 To be 70-80 in 2020 0.73447 70-80 in 2010 To be 80-90 in 2020 0.48423 80+ in 2010 To be 90+ in 2020 0.16396
3.2 Birth Rates
Births are calculated using a ratio method. For each individual TAZ the number of males and females aged 0-10 is compared to the number of females aged 20-40. This ratio is then applied to the number of females aged 20-40 in 2010. This number is then multiplied by the ratio to determine expected number aged 0-10 in 2020 (hence, number of births from 2010 to 2020). Later in the process, additional births and young children of in-migrants are included. This process takes the newly projected age structures and is repeated for the 2030 and 2040 projections. The ratio method has several advantages over trying to apply crude or age- adjusted birth rates. This ratio of children to women of child-bearing age does a good job of taking into account any racial or ethnic differences. Likewise, areas which are partially or predominately populated by women of childbearing age who are students (generally with much lower fertility rates than those in family raising areas) will have a low ratio of children to women of childbearing age.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
3.3 Exceptions to the Survival and Birth Rates
The cohort component method is disregarded in several special cases. Where the population is predominantly institutional (more than fifty percent), such as dormitories, nursing homes, or jails – the assumption is that the age structure of the population will remain constant over the projection period. Thus the elderly nursing home population will simply be replaced by new elderly residents. Dormitories will continue to house predominately young adults, rather than assuming the residents will be ten years older in 2020 than they were in 2010. Therefore the total population and age structure of these TAZs with a majority of their populations in group quarters - remains relatively constant over all projection periods. Fourteen TAZs are designated as institutional (TAZs 6, 7, 17, 25, 44, 45, 47, 57, 120, 146, 167, 1276, and 1594). A total of seventeen additional TAZs had their populations impacted by an institutional presence. Many of these TAZs had nursing homes representing ten to fifty percent of their population, and thus have their totals slightly adjusted to reflect a constant elderly population.
The birth ratio is altered slightly for several TAZs each decade when it appears the rates are unreasonably low or high. Examples are areas which are being rapidly converted from rural agricultural areas to subdivisions with young families. The past ratio fails to take into the account the new dynamics of the younger population. Conversely, an area of single family dwellings which has a new large apartment complex might expect to see its birth ratio lowered in the new decade.
Average household size is calculated for each TAZ. Once the number of new dwelling units is determined for a TAZ, that number is multiplied times the average household size in the TAZ. Average household size in a TAZ is allowed to decrease a maximum of 10% each decade. This is a check on the cohort component method, making sure that new dwelling units are assigned a reasonable number of individuals. 3.4 Migration Component
Under the methodology used in this report, population change is created both from natural increase (births versus deaths) and migration. The expected number of in-migrants is drawn primarily from the number of new dwelling units added in each TAZ. Out-migrants are estimated based on the proportion of the age structure in each TAZ which is in age groups that traditionally out-migrate.
The migration age structures used are drawn from analyzing the age structure of all migrants in Louisiana (2000 Census data) – this representing both those who in-migrate and those who out-migrate – combined to create net migration. To arrive at separate age distributions for in- migrants and out-migrants, numerous census tracts within Lafayette Parish are analyzed. The net migration age structure of very rapidly growing tracts helps form the age structure for the in-migrants, as the vast majority of the migrants in these tracts are, indeed, moving into the
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______area. The net migration age structure of tracts with declining populations helps form the age structure for the out-migrants, as the vast majority of the migrants in these tracts are, indeed, moving out of the area.
The percentages in Table 7 are used to create the age structure for the in-migrants and the percentages in Table 8 used to create the age structure for the out-migrants. Projection years 2010 to 2020 are used in this example, but the values apply to all projection decades.
Table 3-3 Acadiana Metropolitan Planning Organization Age Structure of In-Migrants
In-migration Rate
Born 2010-2020, age 0-10 in 2020 0.196
Age 0-10 in 2010, becoming age 10-20 in 2020 0.161
Age 10-20 in 2010, becoming age 20-30 in 2020 0.141
Age 20-30 in 2010, becoming age 30-40 in 2020 0.186
Age 30-40 in 2010, becoming age 40-50 in 2020 0.225
Age 40-50 in 2010, becoming age 50-60 in 2020 0.082
Age 50-60 in 2010, becoming age 60-70 in 2020 0.035
Age 60-70 in 2010, becoming age 70-80 in 2020 0.021
Age 70-80 in 2010, becoming age 80-90 in 2020 0.014
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______
Table 3-4 Acadiana Metropolitan Planning Organization Age Structure of Out-Migrants
Out-migration Rate
Born 2010-2020, age 0-10 in 2020 0.138
Age 0-10 in 2010, becoming age 10-20 in 2020 0.112
Age 10-20 in 2010, becoming age 20-30 in 2020 0.242
Age 20-30 in 2010, becoming age 30-40 in 2020 0.186
Age 30-40 in 2010, becoming age 40-50 in 2020 0.127
Age 40-50 in 2010, becoming age 50-60 in 2020 0.076
Age 50-60 in 2010, becoming age 60-70 in 2020 0.05
Age 60-70 in 2010, becoming age 70-80 in 2020 0.027
Age 70-80 in 2010, becoming age 80-90 in 2020 0.012
The number of in-migrants is determined primarily by the number of new dwelling units added to a TAZ each decade. Methodology for determining the number of new dwelling units in each TAZ for each projection period is covered in later (section 4.0). The number of dwelling units added in each TAZ is multiplied by the average household size of that TAZ. A small adjustment is made to allow some in-migration in all TAZs – even if they have no new dwelling units. This recognizes that as individuals die, their housing units may be occupied by new residents. The strength of this variable is determined by the number of women who start the year 2000 at ages 70 and older and do not survive the decade to become ages 80 and older in 2010. The lack of survival of these older women, often widows, provides a good indicator of a change in dwelling unit occupancy. For rapidly growing suburban TAZs the impact of this variable is negligible. For older central city TAZs, however, it accounts for recently vacant dwelling units being reoccupied. The number of expected in-migrants is then subdivided by age structure (as cited in Table 7) to determine how many migrants are at each age.
The age structure of the population also determines the amount of expected out-migration from each TAZ. In trying to predict the amount of out-migration in a TAZ, the number of people aged 10 to 18 in 2000, and hence 20 to 28 in 2010, is used as the major indicator. The number of individuals reaching this age indicates how many have reached a stage in the life cycle where they are more likely to move. Basic life cycle reasons include leaving home for employment reasons, leaving to go to school and departing to get married. A secondary
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______indicator is the number of people aged 60 to 70 in 2000 who become 70 to 80 in 2010. This stage of the life cycle is associated with retirement. This does not mean that people of other ages are not also out-migrating, but rather this value is indicative of the expected volume. The number of expected out-migrants is then subdivided by the migration age structure listed in Table 8.
The process is repeated for the 2020 and 2030 projection periods. 3.5 Combining Cohort Component Parts
Several TAZs from the Breaux Bridge area of St. Martin Parish illustrate the combined effects of survival rates, birth ratios and net migration for both the male and female populations of each TAZ. Thus for TAZ 1275, 829.9 of the 896 females in 2010 are expected to survive to 2020. Those females are expected to have 205.8 female births and 210 male births between 2010 and 2020. By comparison, TAZ 1261 has only 646 females in 2010 – but 71.2 aren’t expected to survive – indicating a much older population than TAZ 1275 (where 66.1 out of 896 aren’t expected to survive). Likewise, TAZ 1261 and its older population has relatively few births expected (239.8 versus TAZ 1275’s 415.8). TAZ 1275 is expected to receive relatively modest net in-migration, as its number of dwelling units is expected to remain constant over the decade. Whereas TAZ 1261 is expected to gain 141 new dwelling units between 2010 and 2020, gaining three times as many in-migrants as TAZ 1275.
The cohort component method utilizing survival, birth and migration rates is done in an analogous manner for the 2020 and 2030 population projections.
Table 3-5 Acadiana Metropolitan Planning Organization Example of Survival, Fertility, and Migration Combined
FEM MALE TOTAL TOTAL FEM MALE FEM MALE FEM MALE TAZ Net Net FEM MALE POP POP Survive Survive Births Births Migration Migration POP POP 2010 2010 2020 2020 2010-20 2010-20 2010-20 2010-20 2020 2020 1262 2 3 1.2 2.8 0 0 .5 0 1.7 2.8 1261 646 516 574.8 469.4 118.7 121.1 173.1 177.8 866.6 768.3 1263 109 104 100.8 92.9 17.2 17.6 3.1 3.7 121.1 114.2 1267 61 64 55.6 57.2 8.6 8.8 7.8 8 72.0 74.0 1268 128 135 121.1 124.2 24.8 25.4 20.5 21.4 166.4 171.0 1275 896 794 829.9 738.5 205.8 210.0 59.1 50.9 976.6 897.6 1289 68 47 60.2 43.2 8.4 8.6 2.4 2 66.2 49.8 1254 38 34 34.5 29.9 4.2 4.2 7.1 7.4 45.8 41.5
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______4.0 NEW DWELLING UNITS
With building permit data available for 2010 to 2013 for most of Lafayette Parish, this information is incorporated into the 2020 projection. Taking advantage of increased information will provide a sounder base population in 2020 upon which future projections rely. Once dwelling unit numbers are calculated, adjustments are made to incorporate transportation projects, changes in land available for development, and in the 2030 and 2040 projections - proximity to growth areas. 4.1 Estimation of New Dwelling Units
Estimation of new dwelling units from 2010 to 2020 is done at the individual TAZ level. Rather than use percent change, absolute change in the number of dwelling units is utilized. Information on the number of building permits from 2010 to 2013 is available for most of Lafayette Parish, and that information is factored into an estimation of new dwelling units by 2020. The primary factor in determining new dwelling units is the change in the number of dwelling units from 2000 to 2010. A look at change in dwelling units from 1990 to 2000, where available, also provides historic trends.
Thus for 2010 to 2020, building permits represent approximately one-third of the decade and are weighted evenly with number of new dwelling units from 2000 to 2010. For the 2030 and 2040 projections, change in dwelling units in the past decade is the primary determining factor of number of new dwelling units. Of course, these procedures are then augmented by changes in land availability, transportation projects and proximity to growth areas. 4.2 New Dwelling Unit Methodology Applied to TAZs
The following examples of TAZs from Acadia and Lafayette Parishes illustrate the estimation of new dwelling units for the decade 2010 to 2020. The base calculation is shown, with adjustments to the calculated totals indicated. These adjustments include changes in land availability, transportation improvements and special case considerations. Details on these adjustments can be found in subsequent sections.
Examples from Acadia Parish illustrate several of the basic methods used to determine number of new dwelling units. For TAZ 1003, with 80% land availability – maintain current increase of 30 new dwelling units for the next decade. For TAZ 1004, add 20% to the previous increase (39) to reach 47 new dwelling units. As described under the Land Availability section, a decrease from 80% to 70% land availability seems to be a tipping point to encourage additional development. For TAZ 1005, a drop to 60% land availability brings a 20% decrease in new units – as less land is now available (a drop from 77 to 62). TAZ 1006 had very slow growth (less than 10 new dwelling units), so the past two decades are averaged (5 and 4).
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______Table 4-1 Acadiana Metropolitan Planning Organization Acadia Parish Example – New Dwelling Units 2020
New Land Land DU DU DU DU DU TAZ Parish Av Av Comments 1990 2000 2010 2010- 2020 2000 2010 2020 1003 Acadia 9 8 57 65 95 30 125 Keep current increase 1004 Acadia 8 7 114 105 144 47 191 Tipping pt. for development, increase 20% 1005 Acadia 8 6 137 194 271 62 333 L.A. drops, decrease 20% 1009 Acadia 9 9 20 25 29 4 33 Less than 10 increase, average last 2 decades
Table 4-2 Acadiana Metropolitan Planning Organization Lafayette Parish Examples – New Dwelling Units 2020
TAZ New Bldg Land Land DU DU DU Permits DU Av Av 2010 Trans Comments 2000 2010 2010 - 2020 2000 2010 - 2013 2020 Drop in LA only due to 106 6 4 462 525 1 33 558 including Wetlands ((1*3)+63)/2)=33
142 7 1 93 166 20 186 For LA 1, 20 max
Drop from 50% to 40% LA, 175 5 4 253 467 64 13 544 drop 40% ((0*3)+214)/2)=107 107*.6+64 64+13(T)=13
267 5 5 63 93 210 303 Special Case 332 8 8 83 138 4 33 171 ((4*3)+55)/2)=33 380 6 6 601 688 108 205 893 ((108*3)+87)/2)=205
For the TAZs in Lafayette Parish one can factor in the building permits from 2010 to 2013. Thus for TAZ 106, take the number of building permits (1) times 3, as they represent approximately one-third of the decade – and average that with the change from 2000 to 2010 (63). Averaging 63 and 3 results in 33 new dwelling units being forecast. The drop from
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______60% to 40% land availability should result in a drop of 40% - but does not in this case as the drop was artificial. The only reason for the drop was the exclusion of wetlands in available land in the 2010 definition (they were not excluded under the 2000 definition).
For TAZ 142, a drop to 10% land availability results in a maximum of 20 new units. When TAZs have 20% land availability or less, a set maximum number of new units is prescribed (see Land Availability section), regardless of growth in the previous decade (in this case 73 dwelling units).
TAZ 175 drops in land availability from 50% to 40%, resulting in a 40% decline in new units. There were no new building permits – this averaged with a 2000-10 growth of 214, results in 107 new units. Applying the 40% reduction due to less availability land results in a forecast of 64 new units. This number is augmented by 13 new units as a result of transportation improvements for a final total of 77.
TAZ 267 represents a special case. According to the formula one should forecast 15 new dwelling units (averaging 0 and 30). However, this TAZ has been subdivided into lots and detailed plans put forth for over 200 new dwelling units. This knowledge allows a forecast of 210 new dwelling units by 2020.
TAZs 332 and 380 both retain the same land availability over the past decade. TAZ 332 had 4 building permits from 2010 to 2013 and an increase of 55 units from 2000 to 2010. Averaging those two numbers (12 and 55) for TAZ 332 results in a forecasted increase of 33 dwelling units. For TAZ 380, 108 building permits (times 3 to equal 324) are averaged with an increase of 87 units over the past decade to result in 205 new units. 4.3 Modifications to Dwelling Unit Calculations
The number of new dwelling units expected is modified for a variety of reasons:
Land Availability
Formulas are developed to take into account changes in the amount of land available to residential development. Through the use of Google Earth, each TAZ is examined individually to determine available land. Estimates are made to the nearest 10%. Wetlands are excluded.
Transportation Projects
By 2013, several transportation projects had already been completed and others already started. Additional transportation projects expected to be completed by 2020 and 2030 are also included. For 2020, 60 TAZs have their number of dwelling units increased by 10 percent to represent the positive impact of transportation improvements. 26 TAZs have their number of dwelling units increased by 20 percent to represent the positive impact of transportation improvements expected to have significant impacts during this decade.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______Proximity Variable
For 2030 and 2040, those TAZs adjacent to rapidly growing TAZs have their forecasted number of dwelling units increased. It is assumed that growth is likely to spread out from these rapidly growing cores. No proximity variable is calculated for 2020 – as this initial projection year already takes into account recent activity, expected immediate development and thus is more appropriate for trying to gage where growth over the long term might happen.
Special Cases
For 2020, one has some knowledge of development which is already in the planning stage. Additionally, some TAZs have large tracts of undeveloped land. Where these tracts of land have already been subdivided into lots, this is taken as an indication of potential residential growth. This results in modest increases over the ensuing decades.
High density multi-family dwellings Multi-family dwellings are not dealt with separately, but are built into the basic calculations of new dwelling units. The maximum number of new dwelling units forecast for TAZs with little or no land available for development has been significantly increased. This is a reflection of the growth in many city center TAZs over the past decade, building permits from 2010 to 2013, and from a stated desire to increase residential growth in key core areas (see Land Availability section). Significant growth in several of the special case TAZs reflects the presence of higher density developments.
Group Quarters
Institutional populations (jails, dormitories, nursing homes) are viewed separately from traditional dwelling units. 4.4 Land Available for Residential Development
The percent of land available for residential development in each TAZ is an important variable. Estimates of available land are made for each decade. 2010 estimates are derived primarily from Google Earth aerial images, augmented by personal observations. Land in residential, commercial, industrial, public, and transportation land uses is not deemed available. In addition, for 2010 wetland areas were removed from available land. Estimates are then made for 2020, 2030 and 2040, incorporating the projected growth during the each preceding decade. Percentages are approximate and estimated to the nearest ten percent.
As the amount of available land for residential development decreases in a TAZ, subsequent growth tends to slow down. Research indicates, however, that land with 70-80% availability is associated with the most rapid growth, with the numbers then decreasing with both higher and lower percentages of land available. Thus areas with 70% to 90% of their land available are deemed the most likely for development. These TAZs will have undergone significant residential development yet still have plentiful land available. Those areas with 30% to 70% of their land remaining are still likely candidates for residential development, but large scale subdivisions are not quite as likely. Those areas with under 30% remaining for development
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______are likely to see lesser growth as land is filled in with individual residences on land that is probably more expensive than land in less developed areas. Areas with more than 90% of their land available are also likely to have very slow growth. All of the TAZs, regardless of their classification, remain subject to all the other variables which might encourage or discourage residential construction. 4.5 Land Availability Formulas
TAZs which had rapid growth in a decade may have their classification of percent land available changed for the next projection decade. As the percent of available land changes, the likelihood of future development changes. It is assumed that density changes by approximately two dwelling units per acre when deciding whether to reclassify the amount of available land. Because of the non-linear nature of the relationship between land available and new dwelling units, a simple formula could not be derived. The guidelines in the discussion below are used when readjusting expected projection values.
Areas with little available land (20% and under) have their growth capped with a maximum allowed increase. This dramatically limits future growth in TAZs which experienced rapid growth, but have little space left for more. This handles the small number of TAZs which had a large multifamily unit built, but have little likelihood of another being built in the same TAZ. It recognizes that for TAZs with little or no available land, growth is likely to be slow, regardless of past growth.
Most of the expected growth for each decade is thus focused on those TAZs which have 60% to 90% of their land available for development, while also experiencing significant recent growth. In general, when less land is available for development, the probability of development decreases. The one exception to this generalization is that as TAZs move from 80% to 70% of their land available, this seems to trigger the most rapid rates of growth seen in the study area. Thus when TAZs move from 80% to 70% of their land available, the number of expected new dwelling units rises.
For TAZs with 20% or less available land, growth is capped at a maximum regardless of amount of growth the previous decade. That maximum number decreases as one moves from 20% down to 0% land available. In 2013, several public forums lead to the creation of several preferred growth scenarios for Lafayette Parish. The most popular one identifies several growth cores – most already densely populated. The study foresees significant medium density housing and mixed land uses in these areas. Thus a number of TAZs with very little developable land may see dwelling unit growth. Therefore the maximum number of dwelling units forecast for TAZs with 20% or less available land has been increased.
The following descriptions use the 2010 to 2020 projection to illustrate the methodology. For the 2030 projection, simply add ten years to each of the years presented.
For all TAZs with an increase of 0 to 10 dwelling units in 2000-2010, average that value with the positive change in dwelling units 1990-2000. Maximum growth is 10 dwelling units.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______For TAZs with an increase of more than 10 dwelling units in 2000-2010 –maintain that value unless increase mandates a decrease in available land for next decade.
If a decrease in land available category:
Change from 90% in 2000 to 80% or 70% in 2010 - maintain constant dwelling unit increase.
Change from 80% in 2000 to 70% in 2010 – increase dwelling units 20%
Change from 80% or 70% in 2000 to 60% in 2010 – decrease dwelling units 20%
Change from 60% or less, down one category – decrease dwelling units 40%, down two or more categories - decrease dwelling units 60%.
For TAZs with an increase of more than 10 dwelling units in 2000-2010 – but with 20% or less available land:
0% Available – maximum increase of 15
10% Available – maximum increase of 20
20% Available – maximum increase of 25
Of course, all TAZs are still subject to all the additional variables. Many of the above guidelines are illustrated in the Acadia Parish and Lafayette Parish examples presented earlier. These same principles can be seen in the ensuing examples associated with the transportation variable and the proximity variable. 4.6 Transportation Variable
Transportation improvements will likely have their greatest impacts upon commercial land uses, but are considered to have some affect upon residential development. Most long range transportation improvements are not included in this analysis, as part of the reason for this study is to determine appropriate priorities for years leading up to 2040 – to determine if the present planned improvements are occurring where they will be needed the most. Relevant transportation improvements are taken from the 2040 Financially Constrained Transportation Plan from the Lafayette Consolidated Government and the Metropolitan Planning Organization. Ten major projects and numerous minor ones are included in the 2020 projection. A smaller number of projects are included in the 2030 projection. The extension of I-49 through Lafayette to the southern boundary of the study area is not included. There is still uncertainty about when, and if, this project will be started and completed. It should be noted, however, that significant dwelling unit growth is projected for much of this corridor – through the Broussard area and continuing south. In addition, several transportation projects that are included for 2020 and 2030 do tie into the future I-49 route, further augmenting the projected growth in this corridor.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______Impacts of the transportation improvements are rated as modest or major. Those TAZs with a modest impact have their base number of dwelling units increased by 10% or a minimum of five dwelling units. Those TAZs significantly impacted have their base number of dwelling units increased by 20% or a minimum of 10 dwelling units. TAZs with no dwelling units have no dwelling units added. These TAZs are primarily commercial and industrial in function.
Ten major projects are included in the 2020 projection, impacting 73 TAZs, some in a major way (20% increase in new dwelling units), others in a modest way (10% increase in new dwelling units). The following transportation projects were considered major for 2020:
N. Antoine St. Extension – I-10 to Pont des Mouton Rd.
Apollo Rd. Extension
W. Willow St. widening – University Ave. to Bud St.
Teurlings Dr. Extension – Alexander St. to Louisiana Ave.
Chemin Metairie Parkway – Phase II – LA 89 to Aillet Rd., plus roundabouts
Kaliste Saloom Rd. widening – Amb Caffrey Parkway to E. Broussard Rd.
University Avenue widening – Renaud Dr. to Pont des Mouton Rd.
Louisiana Avenue extension – Maryview Farm Rd. to Gloria Switch Rd.
E. Pont des Mouton Rd. widening – I-49 to Louisiana Ave.
Verot School Rd. widening – Pinhook Rd. to Vincent Rd.
Also included for 2020 are an additional 28 projects with minor impacts. Most of these were the building of roundabouts and additional turning lanes.
For 2030, transportation projects had a major impact on 20 TAZs and a modest impact on 28 additional TAZs. The St. Martinville Bypass also has a modest impact on 10 TAZs for 2040. The following projects were considered major:
2030 - University Avenue widening – Pont des Mouton Rd. to I-49
2030 – Verot School Rd. widening – Amb Caffrey to Chemin Agreable
2030 and 2040 - St. Martinville Bypass 4.7 Proximity to Growth Areas
Growth is deemed more likely when a TAZ is in close proximity to rapidly growing TAZs. Remote areas away from fast growing TAZs are considered less likely candidates for residential growth. Core areas of rapid growth from 2010-2020 are identified. The most
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______rapidly growing TAZs, with an increase of 50 or more dwelling units are each looked at individually. In most instances, substantial new growth is already projected for these TAZs. Adjacent TAZs are likely locations for the spreading of growth. Those TAZs surrounding rapidly growing TAZs receive a 10% increase from the base dwelling unit projection. Those TAZs bordering the very most rapidly growing areas receive a 20% increase. Areas of extensive wetlands are excluded, even when adjacent to rapidly growing areas. For the most part, wetland areas (such as the Lake Martin region of western St. Martin Parish) have had very little growth in past decades and with this methodology generate very little future growth.
Between 2010 and 2020, approximately 86 TAZs grew by more than 50 dwelling units. This provides the basis on which to calculate proximity values for the 2030 projection. 4.8 Examples of Transportation and Proximity Variable Applied to TAZs
TAZs from the Milton area of Lafayette Parish illustrate both the transportation variable and the proximity variable for the 2030 projection. TAZs 380 and 381 form the core area of rapid growth, forecast to increase by 205 and 385 dwelling units respectively between 2010 and 2020. Adjacent TAZs thus have their dwelling unit projections for 2030 increased. For example TAZ 343 sees a modest increase of 5, TAZ 340 a major increase of 10. A transportation project expected to be completed during the 2020’s – the widening of Verot School Road - impacts TAZs 343, 374, 379 and 380. Note that in TAZs 380 and 381 a decline in the land availability (due to huge increases during the 2020’s) results in a reduction in their dwelling unit increase. The result is then augmented by increases due to transportation and proximity.
Table 4-3 Acadiana Metropolitan Planning Organization Adjustments to New Dwelling Units – 2030 Projection
New Total 2010 2020 Land Adjust- Dwelling Dwelling TAZ Dwelling Dwelling Availability Transp. Proximity ment Units Units Units Units Change 2030 2030 340 290 58 10 68 358
343 333 49 24 5 78 411
374 240 32 14 3 49 289
379 47 24 8 2 34 81
380 688 205 -40% 123 30 15 168
381 281 385 -60% 154 15 169
397 253 58 5 63 316
398 236 11 4 15 251
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______The Appendix contains Land Availability values, and adjustment amounts due to Transportation and Proximity for all TAZs for all decades.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______5.0 OCCUPIED AND VACANT DWELLING UNITS
A final step is the designation of dwelling units as occupied or vacant. With an emphasis on using all available land – some demolition of vacant dwelling units is expected. It is forecast that the vacancy rate will slowly decline. The vacancy rate is projected to decline by 20% from 2010 to 2020, and then decline by approximately 30% each ensuing decade. The study area which has a little over 10,000 vacant units in 2010, would end up with approximately 6,000 vacant units in 2040.
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Acadiana Metropolitan Demographic Plan Tech Memo No. 3 ______6.0 CONCLUSIONS
Population projections are seek to predict the future, a difficult task in changing times. A great deal of time and effort was exerted to provide an accurate picture of the study region in 2013. It is hoped that this effort results in greater accuracy for the 2020 projection of dwelling units and population. The 2020 projections utilize a complex cohort component methodology and form a solid structure to base the 2030 and 2040 projections upon.
The intention of this document is to explain the methodology used to project dwelling units and population to the years 2020, 2030 and 2040. Examples are presented with the goal of explaining a somewhat complex procedure in terms that someone without expertise in demography can understand.
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