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Transportation Planning Data

Transportation Planning Data. Needs and Sources CE 451/551 Iowa State University Reg Souleyrette. Source: Transportation Planning Handbook unless otherwise cited. Technical Process - 4 principal steps. Inventory conditions Analyze data to determine relationships

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Transportation Planning Data

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  1. Transportation Planning Data Needs and Sources CE 451/551 Iowa State University Reg Souleyrette Source: Transportation Planning Handbook unless otherwise cited

  2. Technical Process - 4 principal steps • Inventory conditions • Analyze data to determine relationships • Forecast future performance • Evaluate forecasts, recommend improvements

  3. 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!

  4. 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

  5. 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

  6. Census

  7. 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

  8. 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

  9. What is the CTPP 2000? The Census Transportation Planning Package is a set of special tabulations from the long form of the decennial census designed by transportation planners for transportation planners It summarizes the data Flows between Home and Work At Workplace At Residence

  10. Where does the data come from? Long Form

  11. For the U.S. as a whole,about one (1) in six (6) households received the LongForm questionnaire Who got the Long Form?  17%

  12. Key Long Form questions Place of Work Means of Transportation to Work Carpool Occupancy to Work Departure Time for Work Travel Time to Work Vehicles Available € € B B

  13. What are the CTPP 2000 Products? Tabulations at Residence Tabulations at Workplace Flows between Home and Work Part 1Part 2Part 3

  14. Where do I get the CTPP? http://www.transtats.bts.gov/ ASCII Too

  15. What about the data? Let’s Look at the Details So how does this thing work?

  16. Tables—Lots of Tables 121 Tables of Residents’ Based Data 68 Tables of Work Place Data 14 Tables of Flow Data

  17. Variables--Lots of Variables • Person • Worker Status • Age, Sex, Race, Hispanic Origin, Disability Workers • Household • Income • Nos. Vehicles Available • Size and Nos. Workers • Journey-to-Work • Work Location and Mode • Departure and Travel Time • Arrival Time (Calculated)

  18. What is a “Universe”?

  19. Disclosure Review Board

  20. Example of Rounding True Total 354

  21. No record threshold Must have 3 unweighted records

  22. CTPP main page • 2000 CTPP • BTS TranStats web site • Appendix E: CTPP2000 – Standard Tabulations – Sorted by Table Number; Local copy • For variable levels, click here

  23. But what about the ACS? What is the American Community Survey? Replacement of the Long Form Continuous Survey Methodology Conducted Monthly (diaries) Produces Rolling Average Data

  24. Why have an ACS? Eliminate the Census Long Form for 2010 and Thereafter Eliminate the peak in Congressional funding Eliminate the peak in hiring and training Census takers

  25. Main differences between Census Long Form and ACS

  26. Some Emerging Issues People might be counted twice, e.g. once at summer cabin and once at a “permanent home”. Or once at university and once at parent’s home. Areas with seasonal populations, e.g. due to “snow bird” migration, and due to school enrollments, with housing occupancy that varies from 95% to 40% might show up as 80%.

  27. Understanding Sample Error Sample Error is larger because the number of census forms collected each year are smaller. Changes of plus or minus 2% may be due to Sample Error and do not reflect measurable change.

  28. You Cannot compare ACS directly to Decennial data? Carpooling Share NO!

  29. Why Can’t I compare ACS directly to Decennial data Seasonality(12 months instead of "April 1") (different jobs and workers, especially in summer) Group Quarterscurrently not in ACS (plan to add GQ in the future) RepresentationACS has only 1/3 of the nation’s counties (will include ALL counties starting in July 2004) Non-responsefollow-up differences Data collection period(ACS is very long, compared to very short in decennial)

  30. Mail-back rates for Minority populations may be significantly lower A Census Bureau report says that mail-back response rate in neighborhoods that are predominantly African American or Latino are ½ that of predominantly White neighborhoods. Census says they plan to change non- response follow-up plan in these neighborhoods.

  31. 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 types 1) 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 Data 2) 68 Tables of Work Place Data 3) 14 Tables of Flow Data TransCAD also has processing tools

  32. CTPP online access BTS TranStats web site For table descriptions, see: click here For variable levels, see: click here

  33. TIGER files • Census 2000 TIGER/Line Data (from ESRI)

  34. 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

  35. 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.

  36. 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

  37. 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

  38. 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

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