Transportation Planning Data

Needs and Sources

CE 451/551Iowa State University

Reg SouleyretteSource: Transportation Planning Handbook unless otherwise cited

Technical Process - 4 principal steps

• Inventory conditions • Analyze data to determine relationships • Forecast future performance • Evaluate forecasts, recommend

improvements

Typical Information Requirements

• Population and Employment• Land Use• Economic Base• Transportation System• Travel Patterns• Social and Value Factors• Financial Resources• Ordinances, Statutes and Regulations

Good models require good data!

Data by geographic subsystem (in order of increasing area)

• point in urban space is a house number • assessor parcel • block face • block • block group • grid unit • tract • Traffic Analysis Zone (TAZ) (model level) • zone, ring, sector, or district (used to adjust TAZ data in the

aggregate, e.g.for a growth forecast) • political jurisdiction • region

Data Sources

• Census• CTPP• US Census/American Community Survey (ACS)• State Employment Commission (Iowa Work

Force Development)• Market research listings• Building permits• Parcel databases

Very interesting mapping application using census data. http://projects.nytimes.com/census/2010/explorer?hp

Census

Census data and related summaries

Decennial Census summary files •SF 1 (Summary File 1)

• base with all census data • Short-form, basic population data

•SF 3 ( Summary File 3) -• Long form summaries - 1 of 6 households received the

Long form• transportation data relate only to Work trip

•Public Use Micro-Sample Data (PUMS)• 5% sample of long form

Long Form (SF 3) transportation elements

Transportation questions: (within the week of the April 1 survey)

•Did this person do ANY work for either pay or profit?•At what location did this person work?•How many people, including this person, usually rode to work in the car, truck, or van?•What time did this person usually leave home to go to work?•Address of work site?• How many minutes did it usually take this person to get from home to work

WhatWhat is the CTPP 2000? is the CTPP 2000?

The Census Transportation The Census Transportation Planning Package is a set of special Planning Package is a set of special

tabulations from the long form of tabulations from the long form of the decennial census designed by the decennial census designed by

transportation planners for transportation planners for transportation plannerstransportation planners

It summarizes the dataIt summarizes the data

At ResidenceAt ResidenceAt WorkplaceAt Workplace

Flows between Flows between Home and WorkHome and Work

Where does the data come Where does the data come from?from?

Long FormLong Form

For the U.S. as a whole,For the U.S. as a whole,about one (1) in six (6) about one (1) in six (6) households received households received the the LongLong FormForm questionnairequestionnaire

Who got the Long Form?Who got the Long Form?

1717%%

Key Long Form questionsKey Long Form questions

Place of WorkPlace of Work

Means of Transportation to WorkMeans of Transportation to Work

Carpool Occupancy to WorkCarpool Occupancy to Work

Departure Time for WorkDeparture Time for Work

Travel Time to WorkTravel Time to Work

Vehicles AvailableVehicles Available

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WhatWhat are the CTPP 2000 are the CTPP 2000 Products?Products?

Tabulations Tabulations at Residenceat Residence

Tabulations Tabulations at Workplaceat Workplace

Flows between Flows between HomeHome and and WorkWork

Part 1Part 1 Part 2Part 2 Part 3Part 3

Where do I get the CTPP?Where do I get the CTPP?

http://www.transtats.bts.gov/http://www.transtats.bts.gov/

ASCII TooASCII Too

What about the data?What about the data?Let’s Look at the DetailsLet’s Look at the Details

So how does this thing work?

Tables—Lots of TablesTables—Lots of Tables

121 Tables of Residents’ Based Data121 Tables of Residents’ Based Data

68 Tables of Work Place Data68 Tables of Work Place Data

14 Tables of Flow Data14 Tables of Flow Data

Variables--Variables--Lots of VariablesLots of Variables

Journey-to-WorkJourney-to-WorkWork Location and Mode Departure and Travel TimeArrival Time (Calculated)

HouseholdHouseholdIncomeNos. Vehicles AvailableSize and Nos. Workers

PersonPersonWorker StatusAge, Sex, Race, Hispanic Origin, Disability

WorkersWorkers

Geography--Lots of Geography

T A Z

or Block Groups

Part 1 1 2 1 T a b l e s(at Residence)

Part 2(at Workplace)

Part 3(Worker Flows)

1 4 T a b l e s

6 8 T a b l e s

What is a “Universe”?What is a “Universe”?

Total Total Total TotalDrove Alone Drove Alone Drove Alone Drove Alone

2 Person Carpool 2 Person Carpool 2 Person Carpool3 Person Carpool 3 Person Carpool4 Person Carpool

5-6 Person Carpool7+ Person Carpool

Bus/Trolley Bus Bus/Trolley Bus Bus or Trolley BusStreetcar/TrolleySubway/Elevated

RailroadFerryboat

BicycleWalkedTaxicab

MotorcycleOther Means

Worked at Home Worked at Home Worked at Home

18 Modes 11 Modes 8 Modes 5 Modes

Bicycle/Walked

Taxicab/ Motorcycle/other

Means

Bus/Trolley Bus/ Streetcar/Trolley/ Subway/Elevated/

Railroad/ Ferryboat

Bicycle/ Walked/ Taxicab/

Motorcycle/other Means/ Worked at

Home

Streetcar/Trolley/ Subway/Elevated/

Railroad/ Ferryboat

Bicycle/Walked/ Taxicab/

Motorcycle/other Means

Streetcar/Trolley/ Subway/Elevated

Railroad/ Ferryboat

Means of Transportation to Work

3+ Person Carpool2+ Person Carpool

4+ Person Carpool

Disclosure Review BoardDisclosure Review Board

CTPP 2000 Post DRB

Part 1: at Residence (121 Tables) All Tables Rounded Zero = 0 1 through 7 = 4 8 though = Nearest Multiple of “5”

Part 2: at Workplace (68 Tables) All Tables Rounded

Part 3: Worker Flows (14 Tables) All Tables Rounded Some Tables with Thresholds

Mode to Work

Circa 1990For 2000

(ROUNDED)

Total 352 350 (not 355!)

Drive Alone 212 210

Carpool 46 45

Transit 59 60

Walk 33 35

Bike 2 4

Example of RoundingExample of Rounding

True Total 354True Total 354

Table Content

1 Total Workers (1)

2 Vehicles Available (3--zero,one or two+) by Means of Transportation (7 modes)

3 Poverty Status (3 categories)

4 Minority Status (2--white non-hispanic and all others)

5 Household Income (8 classifications)

6 Means of Transportation (17 modes)

7 Household Income (4 classifications) by Means of Transportation (4 modes)

8Mean Travel Time by Means of Transportation to Work (7 modes) and Time

Leaving Home for Work (2--AM peak and all other times)

9Median Travel Time by Means of Transportation to Work (7 modes) and Time

Leaving Home for Work (2 groupings)

10 Aggregate Number of Vehicles by Time Leaving Home for Work (2, see table 8)

11 Number of Workers per Vehicle by Time Leaving Home for Work (2, see table 8)

12 Aggregate Number of Carpools by Time Leaving Home for Work (2, see table 8)

13 Number of Workers per Carpool by Time Leaving Home for Work (2, see table 8)

14Aggregate Travel Time by Means of transportation to work (7 modes) and Time

Leaving Home for Work (2, see table 8)

Part 3: Worker Flow Tables

No record No record thresholdthreshold

Must have 3 Must have 3

unweighted unweighted

recordsrecords

• CTPP main page– 2000 CTPP– BTS TranStats web site– Appendix E: CTPP2000 – Standard Tabulations – So

rted by Table Number; Local copy

– For variable levels, click here

But what about the ACS?But what about the ACS?

What is the American What is the American Community Survey?Community Survey?

Replacement of the Long FormReplacement of the Long Form

Continuous Survey MethodologyContinuous Survey Methodology

Conducted Monthly (diaries)Conducted Monthly (diaries)

Produces Rolling Average DataProduces Rolling Average Data

Why have an ACS?Why have an ACS?

Eliminate the Census Long Form for Eliminate the Census Long Form for 2010 and Thereafter2010 and Thereafter

Eliminate the peak in Congressional Eliminate the peak in Congressional fundingfunding

Eliminate the peak in hiring andEliminate the peak in hiring and training training Census takersCensus takers

Decennial CensusDecennial Census ACSACS

Sample: 1 in 6 Hhlds Sample: 1 in 6 Hhlds

(17% Sample)(17% Sample)

Sample: 1 in approx 40 Sample: 1 in approx 40 households each yearhouseholds each year

(2.5%/yr 12.5% @ 5 yrs)(2.5%/yr 12.5% @ 5 yrs)

Time reference: April 1, Time reference: April 1, 2000 or April 1, 20102000 or April 1, 2010

(Last Week)(Last Week)

Time reference: Time reference: Continuous including all Continuous including all 12 months12 months

Data is outdated quicklyData is outdated quickly Requires accumulation Requires accumulation over multiple years for over multiple years for small area reportingsmall area reporting

Main differences between Census Long Form Main differences between Census Long Form and ACSand ACS

Some Emerging IssuesSome Emerging Issues

People might be counted twicePeople might be counted twice, e.g. once at , e.g. once at summer cabin and once at a “permanent home”. summer cabin and once at a “permanent home”. Or once at university and once at parent’s home.Or once at university and once at parent’s home.

Areas with seasonal populationsAreas with seasonal populations, e.g. due to , e.g. due to “snow bird” migration, and due to school “snow bird” migration, and due to school enrollments, with housing occupancy that varies enrollments, with housing occupancy that varies from 95% to 40% might show up as 80%.from 95% to 40% might show up as 80%.

Sample ErrorSample Error is larger because the number of is larger because the number of census forms collected each year are smaller. census forms collected each year are smaller.

Changes of plus or minus 2% may be due to Changes of plus or minus 2% may be due to Sample Sample ErrorError and do not reflect measurable change. and do not reflect measurable change.

Understanding Sample ErrorUnderstanding Sample Error

NO!NO!

Cannot compare ACS directly Cannot compare ACS directly to Decennial data? to Decennial data?

Carpooling ShareCarpooling Share

YouYou

Can’t I compare ACS directly Can’t I compare ACS directly to Decennial data to Decennial data

WhyWhy

SeasonalitySeasonality (12 months instead of "April 1") (different jobs (12 months instead of "April 1") (different jobs and workers, especially in summer)and workers, especially in summer)

Group QuartersGroup Quarters currently not in ACS currently not in ACS (plan to add GQ (plan to add GQ in the future) in the future)

RepresentationRepresentation ACS has only 1/3 of the nation’s counties ACS has only 1/3 of the nation’s counties (will include ALL counties starting in July 2004)(will include ALL counties starting in July 2004)

Non-responseNon-response follow-up differencesfollow-up differences

Data collection periodData collection period (ACS is very long, compared to (ACS is very long, compared to

very short in decennial)very short in decennial)

Mail-back rates for Minority Mail-back rates for Minority populations may be significantly populations may be significantly lowerlower

A Census Bureau report says that mail-back A Census Bureau report says that mail-back response rate in neighborhoods that are response rate in neighborhoods that are predominantly African American or Latino are ½ predominantly African American or Latino are ½ that of predominantly White neighborhoods.that of predominantly White neighborhoods.

Census says they plan to change non-Census says they plan to change non-response follow-up plan in these neighborhoods.response follow-up plan in these neighborhoods.

Census Transportation Planning Package (CTPP)

Same data as in the long form

Pre-processed tables plus capture tools to formulate your own data tables and maps are provided

CTTP Tables of three summary types1) At residence (Part 1)

2) At work place (Part 2) 3) travel between work and home (Part 3)

Prepared sets of Tables from CTPP include:1) 121 Tables of Residents’ Based Data2) 68 Tables of Work Place Data3) 14 Tables of Flow Data

TransCAD also has processing tools

BTS TranStats web siteFor table descriptions, see: click here For variable levels, see: click here

CTPP online access

TIGER files

• Census 2000 TIGER/Line Data (from ESRI)

NHTS data can be used to investigate topics in:

• transportation safety• congestion• mobility of various population groups• relationship of personal travel to economic

productivity• the impact of travel on the human and natural

environment

NHTS• Long term trends• 26,000 national samples• 40,000 “add-on” samples

• 24 hr (local) and 28 day (long distance) diaries• 1977 and 1995 ATS (long dist)• 2001 did both local and long dist.

Other internet sources• Census Fact Finder• Ed the Fed

• http://www.surveyarchive.org/index.html• Iowa Department of Transportation (IowaDOTMaps.com) • ISU Geographic Information Systems (GIS) Facility

– Geospatial Data Explorer– Orthophphotos

• http://earth.google.com/ • Iowa Department of Natural Resources • ISU’s SETA (Social and Economic Trend Analysis)• Quarterly Census of Employment and Wages (ES202)

• MPOs, cities and other state DOTs – much more

More data sources

• windshield surveys • land use maps • tax assessor files • business license files • zoning maps • local records, city

directories, rural directories (for outlying areas)

• building and occupancy permits

• utility companies

• business data files (may be confidential)

• Polk directories, Dun and Bradstreet and others

• Telephone directory• Aerial remote sensing and

satellite images• State department of finance• Local planning departments

Studies

• Volume Studies– Average daily traffic counts – Hourly Counts – Peak Hour Counts – Cordon Counts – Screenline Counts – Projected flow (future

volumes) • Capacity Studies

– Freeway and multilane highway segments

– 2-Lane highways – Signalized intersections

• Pedestrian Studies– Volumes – Flow characteristics – Capacity analysis – Walking speed

• Mass Transit Studies– Transit capacity and level of

service – Transit origin-destination studies – Load and boarding checks – Speed and delay

• Parking Studies– Supply and demand – User characteristics – Occupancy rates – Turnover rates