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

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
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Inventory conditions
Analyze data to determine relationships
Forecast future performance
Evaluate forecasts, recommend
improvements
Typical Information Requirements
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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)
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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
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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
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
Where does the data come
from?
Who got the Long Form?
For the U.S. as a whole,
about one (1) in six (6)
households received
the Long Form
questionnaire
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Key Long Form questions
Place of Work
Means of Transportation to Work
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Carpool Occupancy to Work
Departure Time for Work
B
Travel Time to Work
Vehicles Available
B
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What are the CTPP 2000
Products?
Tabulations
at Residence
Tabulations
at Workplace
Flows between
Home and Work
Part 1
Part 2
Part 3
Where do I get the CTPP?
http://www.transtats.bts.gov/
What about the data?
Let’s Look at the Details
So how does this thing work?
Tables—Lots of Tables
121 Tables of Residents’ Based Data
68 Tables of Work Place Data
14 Tables of Flow Data
Variables--Lots of Variables
Person
Worker Status
Age, Sex, Race, Hispanic
Origin, Disability
Household
Income
Nos. Vehicles Available
Size and Nos. Workers
Workers
Journey-to-Work
Work Location and Mode
Departure and Travel Time
Arrival Time (Calculated)
What is a “Universe”?
Means of Transportation to Work
Total
Drove Alone
2 Person Carpool
3 Person Carpool
4 Person Carpool
5-6 Person Carpool
7+ Person Carpool
Bus/Trolley Bus
Streetcar/Trolley
Subway/Elevated
Railroad
Ferryboat
Bicycle
Walked
Taxicab
Motorcycle
Other Means
Worked at Home
18 Modes
Total
Drove Alone
2 Person Carpool
3 Person Carpool
4+ Person Carpool
Total
Drove Alone
2 Person Carpool
3+ Person Carpool
Bus/Trolley Bus
Streetcar/Trolley/
Subway/Elevated
Bus or Trolley Bus
Bicycle/Walked
Bicycle/Walked/
Taxicab/
Motorcycle/other
Means
Total
Drove Alone
2+ Person Carpool
Bus/Trolley Bus/
Streetcar/Trolley/ Streetcar/Trolley/
Subway/Elevated/ Subway/Elevated/
Railroad/ Ferryboat Railroad/ Ferryboat Railroad/ Ferryboat
Taxicab/
Motorcycle/other
Means
Worked at Home
11 Modes
Worked at Home
8 Modes
Bicycle/ Walked/
Taxicab/
Motorcycle/other
Means/ Worked at
Home
5 Modes
Disclosure 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
Example of Rounding
Mode to
Work
Circa 1990
For 2000
(ROUNDED)
Total
Drive Alone
Carpool
Transit
Walk
Bike
352
212
46
59
33
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350 (not 355!)
210
45
60
35
4
True Total 354
Part 3: Worker Flow Tables
Table
Content
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Total Workers (1)
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Vehicles Available (3--zero,one or two+) by Means of Transportation (7 modes)
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Poverty Status (3 categories)
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Minority Status (2--white non-hispanic and all others)
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Household Income (8 classifications)
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Means of Transportation (17 modes)
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Household Income (4 classifications) by Means of Transportation (4 modes)
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No record
threshold
Must have 3
unweighted
records
Mean Travel Time by Means of Transportation to Work (7 modes) and Time
Leaving Home for Work (2--AM peak and all other times)
Median Travel Time by Means of Transportation to Work (7 modes) and Time
Leaving Home for Work (2 groupings)
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Aggregate Number of Vehicles by Time Leaving Home for Work (2, see table 8)
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Number of Workers per Vehicle by Time Leaving Home for Work (2, see table 8)
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Aggregate Number of Carpools by Time Leaving Home for Work (2, see table 8)
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Number of Workers per Carpool by Time Leaving Home for Work (2, see table 8)
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Aggregate Travel Time by Means of transportation to work (7 modes) and Time
Leaving Home for Work (2, see table 8)
• 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
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
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
Main differences between Census Long Form
and ACS
Decennial Census
Sample: 1 in 6 Hhlds
(17% Sample)
Time reference: April 1,
2000 or April 1, 2010
(Last Week)
Data is outdated quickly
ACS
Sample: 1 in approx 40
households each year
(2.5%/yr 12.5% @ 5 yrs)
Time reference:
Continuous including all
12 months
Requires accumulation
over multiple years for
small area reporting
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%.
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.
You
Cannot compare ACS directly
to Decennial data?
Carpooling Share
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12.2
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NO!
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10.4
Decennial
ACS
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1999
2000
2001
2002
2003
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 Quarters currently not in ACS (plan to add GQ
in the future)
Representation ACS has only 1/3 of the nation’s counties
(will include ALL counties starting in July 2004)
Non-response follow-up differences
Data collection period (ACS is very long, compared to
very short in decennial)
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 nonresponse 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 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
CTPP online access
BTS TranStats web site
For table descriptions, see: click here
For variable levels, see: click here
TIGER files
• Census 2000 TIGER/Line Data (from ESRI)
NHTS data can be used to investigate topics in:
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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
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– 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
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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
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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
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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
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Supply and demand
User characteristics
Occupancy rates
Turnover rates