STEP3: Micro-simulation-Based Small Area Demographic Forecasts for Clark County

Stewart BerrySrinivasan SundaramHoward Slavin

Caliper Corporation2007

Introduction

• This project entailed development

and application of STEP3- a disaggregate household microsimulation model

• STEP3 produces small area population forecasts for Clark County

• STEP3 can be used for planning, impact assessment and monitoring

STEP3 Framework

HOUSEHOLD BEHAVIOR(Simulates behavior for individual households and

persons)

Zone Data(Employment and Landuse

Data, Transportation and Accessibility)

POPULATION SYNTHESIS(Generates Household and Person databases that are

representative of the population)

POPULATION PROGRESSION(Progresses population through vital life events)

- Population Progression- Workforce Participation- Retirement status

Model Component

Model Flow

Input/Output File

Input/Output Flow

LANDUSE MODELING

- Employment Location- Housing Location

Zone Data: Demographic splits by Household

Size, Income, Age of Head of Household, etc.)

PUMS data: Individual Household Person Census Records

Synthetic Person File

Synthetic Household File

Lifestyle and Mobility Decisions

- Residential Location- Workplace Location

Synthetic Household FileSynthetic Person File

Population Progression

Aging, Mortality and Births

• Age by 1 year• Education of children is increased• Income and wages increase• Death rates are applied• Birth rates are applied

Household Formation

• Kids Leave home at age 22

– Vehicles, employment & income are calculated

• Divorces happen– Income & vehicles are split; children are

assigned using custody probability

• Marriages happen– Single men are identified & potential

brides are searched for based on age

Migration

• Regional in- and out- migration is

modeled using rates from IRS tax returns

• Intra-county migration is modeled using rates from the 2000 Census

Labor Force Participation

• Worker status

– Determined by gender, age, race, marital status & children by age

• Retired status– If aged 65+, retirement status is

determined by gender, age & household structure

• Unemployed status– Determined using published Clark County

rates

Land Use Modeling

External Inputs

• The user can add planned residential

and employment buildings:– Construction year– The number of owner/renter units– The number of jobs in 7 sectors:

• Hotel• Office• Industrial• Regional Retail• Community Retail• Neighborhood Retail• Other Non-Retail

Post-2000 Development Layer

Undevelopable Land Constraints

• Undevelopable land restricts growth:

– Military installations– Airports– Water bodies– Parks– Steep gradient – Constrained lands

Residential Cell Growth

• The user can increase or decrease

settlement sprawl and density• A cell can be developed when it:

– Has developable land– Has 2 neighboring cells with 919 people in

each– Is not a group quarters cell

Cell Characteristics Influencing Urban Growth

Employment Seeds

• Non-retail employment grows using:

– Future land-use layer- Growth rates

• Retail employment grows using: – “Hot-spots” that identify areas where

there is high population but little retail

Locational Choices

Hotel/Gaming Industry Workers

• Choose work zone first• Employment preferences:

– CBD – Strip– High employment zones

• Residence preferences:– Income– Owner or renter status– Travel time to work– Number of units available

All Other Workers

• Choose residence zone first• Residence preferences:

– Income– Owner or renter status– Average travel time to work– Number of units available

• Employment preferences:– CBD – Strip– Closeness to home zone– Vehicle & transit travel times & costs

Socio-economic Trends in Clark County

Time-Series of Socio-Economic Data (1990-2005)

• High population growth• Trend of higher percentage of

workers• But population is still growing faster

than the employed• Migration is a major factor in growth

Time Series of Migration

Time-Series of Socio-Economic Data

020000400006000080000

100000120000140000160000

1990

1992

1994

1996

1998

2000

2002

2004

Year

Per

son

s

Inmigration

Outmigration

Previous Population Projections & Estimates

• Five sets of projections and

estimates– Caliper Tract Estimates– IRS tax returns (highest)– State Demographer– REMI– RTC-SNWA-CCCP-CBER (highest)

• Overall trends are consistent• STEP3

– Scenarios model these upper and lower bounds

Population Projections and Estimates

0

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022 2024 2026 2028 2030 2032 2034

Year

Popu

lation

Caliper Tract Estimates

Comp. Plan

State Demographer

IRS

REMI

Development of the Spatial Database for Analysis

• 1km grid cells• The land use types are:

– Hotel– Office– Industrial– Regional Retail– Community Retail– Other Retail– Other Non-Retail– Renter Occupied– Owner Occupied

Model Structure

Input Data Model Database

Census aggregate andPUMS data: Individual

Household & Person Census Records

Zone Data: Demographic splits by Household Size, Income, Age of Head of Household; Employment and Land Use Data; Employment & Housing Location; etc.

County Business Patterns Employment File

Synthetic Person File

Synthetic Household File

GIS Overlays: Slope/gradient, physical features, human

landmarks

Data Integration in TransCAD

Census Data

Aggregate Zonal Disaggregate Household Disaggregate PersonPopulation Number of people in

householdRelationship to householder

Dwelling Units Place of residence GenderOccupied Housing Units by Tenure

Number of automobiles Race

Median Rent Household income AgeMedian Owner Costs Rent or own EthnicityAggregate Household Income 1999

Group Quarters Type of Education

Occupied Housing Units by Tenure by Car Ownership

Years of schooling

Household Income Employment status

Occupied Housing Units by Tenure by Householder Age

Hours worked last week

Occupied Housing Units by Household Size

Place of work

Group Quarters Industry

Total person's income

Wages or salary

Nonfarm self-employment

Subfamily Relationship

Marital Status

Las Vegas Valley Landmarks

2004 Las Vegas Landuse Types, Gradients & Undevelopable Land

Road Network (2000-2005)

Forecast Results

Results Overview

• Four STEP3 scenarios – High growth with extensive urban dispersion – High growth with constrained urban

dispersion – Lower growth with extensive urban dispersion – Lower growth with constrained dispersion

• The upper bound forecasts exceed the CCCP population forecast

• The lower bound trends are more inline with REMI and the State Demographer

Population Projections

Population Projections

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

4,000,000

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

2021

2022

2023

2024

2025

Year

Po

pu

lati

on

Comp. Plan

State Demographer

REMI

Caliper LBF

Caliper UBF

Upper Bound Forecasts

• Increases in:

– Population– Households– Movers and immigrants– Workers, retirees and non-workers, while

unemployment stabilizes at about 4%

• Constrained scenario growth: – Moapa– Goodsprings (east & south)– Searchlight & CAL-NEV-ARI– Primm-Roach-Borax corridor– Boulder City (south)– Las Vegas (north, south-east, south-west,

west)

Upper Bound Workers

Workers

0

100,000

200,000

300,000

400,000

500,000

600,000

2000

2003

2006

2009

2012

2015

2018

2021

2024

Year

To

tal

Hotel

Office

Industrial

Regional Retail

Community Retail

Neighborhood Retail

Other Non-Retail

New Populated Cells 2000-2025 (upper bound; black are post-2000)

New Populated Cells 2000-2025 (upper bound dispersion; black are post-2000)

Lower Bound Forecasts

• Increases in:

– Population– Households– Movers and immigrants– Workers, retirees and non-workers, while

unemployment stabilizes at about 4%

• Constrained scenario growth: – Moapa– Goodsprings (east)– Searchlight– Primm-Roach-Borax corridor– Boulder City (south)– Las Vegas (north, south-east, south-west,

west)

Lower Bound Workers

Workers

050,000

100,000150,000200,000250,000300,000350,000400,000450,000

2000

2003

2006

2009

2012

2015

2018

2021

2024

Year

To

tal

Hotel

Office

Industrial

Regional Retail

Community Retail

Neighborhood Retail

Other Non-Retail

New Populated Cells 2000-2025 (lower bound; black are post-2000)

New Populated Cells 2000-2025 (lower bound dispersion; black are post-2000)

Model Interface

Description of Model Stages

• Stage 1: Population Synthesis • Stage 2: Zone and Network Processing• Stage 3: Population Progression• Stage 4: Landuse Modeling• Stage 5: Residential Location• Stage 6: Work Location• All Stages: Feedback Loop

Description of Default Scenarios

• Scenario 1: Upper Bound Population

Forecast with Constrained Cell Growth• Scenario 2: Lower Bound Population

Forecast with Constrained Cell Growth• Scenario 3: Upper Bound Population

Forecast with Unconstrained Cell Growth• Scenario 4: Lower Bound Population

Forecast with Unconstrained Cell Growth

Time Series Visualization Tool

• Once STEP3 has been run, the zonal

output can be displayed as a time series:

Future Land-use Database Editing Tool

• The geography of the future land use

layer can be modified:

Land Use Evolution

Case StudyImplications for HAZMAT Exposure

Discussion

• Yucca Mountain Repository for

radioactive waste• Proximity to Clark County of the

facility and transportation routes• STEP3 is used to explore the

projected population that could be exposed

Proposed Nuclear Waste Routes

Projected Population Exposure

• 800 meter (½ mile) buffer• Higher population along the highway

than the rail line• More people exposed in the

dispersion scenarios at the beginning, but are less than the constrained towards 2025

Exposed Population Along Highway Corridor (Clark County)

Exposed Population Along Highway Corridor

0

20000

40000

60000

80000

100000

120000

2000

2003

2006

2009

2012

2015

2018

2021

2024

Year

Po

pu

lati

on LBF Hywy

LBF Disperse Hywy

UBF Hywy

UBF Disperse Hywy

Exposed Population Along Rail Corridor (Clark County)

Exposed Population Along Rail Corridor

0

50000

100000

150000

200000

250000

300000

2000

2003

2006

2009

2012

2015

2018

2021

2024

Year

Po

pu

lati

on LBF Rail

LBF Disperse Rail

UBF Rail

UBF Disperse Rail

Conclusion

• The settled area has grown

enormously and continued sprawl is expected

• Even though predictions are uncertain, planning is aided by forecasts that predict where people live and work

• Household microsimulation, with all its limitations, can be a practical tool for demographic and land use forecasting