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					Wrapping up the CTPP
What you should know
              Ed J. Christopher
        FHWA Resource Center near Chicago
            19900 Governors Drive
           Olympia Fields, IL 60461

                  708-283-3534
            edc@edthefed.com


            April 26, 2005
  Today



Run Through CTPP
Cover Some CTPP/Census Data
Issues
     What is the CTPP?
     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
 CTPP Main Products




 Tabulations   Tabulations    Flows between
at Residence   at Workplace   Home and Work

  Part 1        Part 2          Part 3
How is it packaged?



                      CTPP Access Tool
                         The CAT



                              ASCII Too
When was it released?

  Part 1 -- Residence Data (Done)
       BTS has Final ASCII version on TranStats
       Final CAT Files distributed to MPOs / states
  Part 2—Work Place Data (Done)
       Final ASCII on BTS TranStats
       Final CAT @ BTS Bookstore

  Part 3— Flow Data
       Final ASCII (Done)
       Coming Soon!!!!!
Where do I get the “FREE”
   CTPP ASCII Files?




      http://www.transtats.bts.gov/
Where do I get the “FREE”
  CTPP with Software?




      https://www.bts.gov/pdc/
Install New (Part 3) Viewer Software
CTPP Data Issues


   Rounding and Thresholds
   Workplace Geocoding
   Worker Counts
   Top Coding
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                     For 2000
              Circa 1990
  Work                     (ROUNDED)
   Total         352       350 (not 355!)
Drive Alone      212            210
 Carpool          46             45
  Transit         59             60
   Walk           33             35
    Bike           2              4
                            True Total 354
           Pop Quiz!



    Using the CTPP, 10 + 10 + 10 + 10 = ?
           a) 30        c) 35        e) 40
           b) 45        d) 50        f) Any of the
                                        Above
Here's a real life example using the CTPP Part 2 data. Let's
say my boss asks as simple question: "How many transit
commuters are at work in the Bay Area?" Using the Part 2
data, I am able to provide my boss 15 different answers!
                                       Chuck Purvis, MTC
      Chicago CBD -CTPP 2000 Data

          Total   SOV Carpool Bus       Rail   Other Home     Row Tot
L11423    49,275 12,200  3,915 6,410    24,580 2,160  10       49,275
L11428    29,365 8,315   2,340 4,210    12,780 1,715   4       29,364
L11446    15,035 3,705   1,240 2,430     7,010   640  15       15,040
L11448     5,200 3,115     550    570      745   150  65       5,195
L11449    25,655 7,240   2,120 2,775    12,325 1,195   0       25,655
L12427       920    410    155     65       85    95 105        915
L12428     9,610 3,025     835 1,660     3,535   555   0       9,610
L12446    22,115 4,925   1,770 4,595     9,915   905   0       22,110
L12449    67,795 14,565  4,820 8,035    36,950 3,420   0       67,790
 Rest    124,955 34,255 10,324 17,410   57,165 5,460 328      124,942
                                                              349,896
Col Tot 349,925 91,755   28,069 48,160 165,090 16,295   527
    Mode to Work for Travis County Residents
               Total      Car, truck, van   Drove alone
Tract
         SF3       CTPP   SF3      CTPP     SF3    CTPP
 1.01    2,021   2020    1,850    1845   1,697    1695
 1.02    1,231   1230    1,099    1094   1,062    1060
 2.01    3,614   3615    2,899    2905   2,573    2575
 2.03     243     245     191      190    129      130
 2.04    2,036   2035    1,605    1605   1,485    1485
 3.01    4,084   4085    3,065    3065   2,686    2685
 3.02    3,342   3340    2,352    2350   2,194    2195
 3.03    1,766   1765    1,373    1370   1,074    1075
24.18    2,296   2295    2,134    2135   1,758    1760
24.19    2,207   2205    2,072    2070   1,831    1830
 24.2    4,088   4090    3,747    3750   2,955    2955
24.21    2,246   2245    2,133    2130   1,786    1785
24.22    3,045   3045    2,725    2725   2,122    2120
24.23    3,116   3115    2,925    2930   2,489    2490
24.24    1,889   1890    1,757    1754   1,416    1415
        433,064 433,080 383,508 383,409 324,475 324,430
                0.004%          -0.026%         -0.014%
Means of Transportation to Work for DC Residents
             Total            Car, truck, van       Drove alone
Tract
         SF3     CTPP         SF3      CTPP        SF3     CTPP
     1   3,040     3,040       1,334     1,335     1,150     1,150
  2.01   2,322     2,320       1,362     1,360     1,025     1,025
  2.02   2,401     2,400       1,165     1,160       942       940
     3   3,875     3,875       2,247     2,244     1,861     1,860
     4     825       825         499       500       453       455
  5.01   2,015     2,015         607       610       503       505
  5.02   2,212     2,210         854       855       736       735
     6   2,671     2,670       1,372     1,350     1,045     1,045
 99.01   1,009     1,010         786       780       637       635
 99.02   1,049     1,050         664       665       486       485
 99.03     509       510         263       265       184       185
 99.04     688       690         333       335       250       250
 99.05     863       865         533       529       394       395
 99.06     391       390         194       185       147       145
 99.07     730       730         410       415       303       305
         260,884    260,890   128,775    128,194   100,168    100,164
                   -0.002%              0.451%               0.004%
               Rounding Tips

1. Obtain your "regional control totals" from the
   most geographically aggregate summary levels
2. Avoid aggregating (summing together) your
   geographies
3. Avoid aggregating categories
4. Sum as few categories as possible
5. Adjust (de-round, un-round) as you see fit.
   SF3 or PUMS can provide control totals to
   adjust the CTPP Part 1 data.
6. Develop a sense of humor.

So is it "close enough for government work?"
Odd Modes




        Linn County, Cedar Rapids Iowa
Odd Modes




        Linn County, Cedar Rapids Iowa
Thresholds

  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
                    Part 3: Worker Flow Tables
Table                                        Content
                                                                                   No record
  1                                      Total Workers (1)                         threshold
  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)   Must have 3
  5                            Household Income (8 classifications)              unweighted
  6                           Means of Transportation (17 modes)                 records
  7        Household Income (4 classifications) by Means of Transportation (4 modes)
         Mean Travel Time by Means of Transportation to Work (7 modes) and Time
  8
                    Leaving Home for Work (2--AM peak and all other times)
         Median Travel Time by Means of Transportation to Work (7 modes) and Time
  9
                            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)
        Aggregate Travel Time by Means of transportation to work (7 modes) and Time
 14
                           Leaving Home for Work (2, see table 8)
            DRB Impact on Part 3

Intra-Bay Area, CTPP 2000, Part 3 Analysis
                     Table 3-1                  Table 3-6
                    No Threshold              w/ Thresholds
County-to-County   3,258,465    Loss        3,258,465      Loss
 Place-to-Place    3,257,152     0.0%       3,221,359      -1.1%
 Tract-to-Tract    3,209,952    -1.5%       2,154,754 -33.9%
  Zone-to-Zone     3,143,432    -3.5%          937,749 -71.2%
                               Special Thanks to Chuck Purvis, MTC
                                                   For this Analysis
Workplace Geocoding
Workplace Geocoding
Workplace Geocoding Issues


    Automatic Geocoding (75%)
    Standard Allocation (25%)

    Industry Improvements
        m   TIGER Improvements (TAZ Definition)
        m   Work-up Clean-up
        m   Extended allocation 10% (ala Lemoges)
Workers at Work Counts vs.
Other Employment Sources
Total jobs are HIGHER than Census 2000 worker
counts while CTPP Part 3 is Lower yet! (Rounding)
CTPP uses NAICS, others may use SIC
Multi-site businesses and job types not reported
consistently
Census 2000 employment estimates vs CPS
Extended Allocation for CTPP small areas

http://www.trbcensus.com/articles/ctppworkers.pdf
Top Coding of Travel Time


The top coding of travel time changed
between 1990 and 2000. In 1990, the
data field for travel time was limited to
2 digits thereby restricting travel time
to a maximum of 99 minutes. In 2000,
the field was 3 digits with a top coding
of 200 minutes.
Top Coding
When I get my CTPP data what should I do?

   Examine the data for your area as soon as
   possible

   Check its reasonableness
         Does it make sense?
         Are people working where they should be?
         Do the tables add up?

   Report all data issues to Nanda Srinivasan, FHWA,
   (Phone 202-366-5021, email
   nanda.srinivasan@fhwa.dot.gov)
 Stay Connected



         http://www.dot.gov/ctpp
      http://www.TRBcensus.com

              202-366-5000
      Are You on the CTPP-News Listserve?
Have You Seen our Newsletter (the Status Report)?
    When Mining Your Census Data
          Keep us in Mind
Want to…
 Show Off Your Work?
 Gain National Exposure?
 Meet Other Data Users?
 Tour Washington DC?
              Sound Exciting?
      Let Us Know What You Have Done
         We Are Always Interested
       TRB Urban Data and Information Systems Committee
             Ed Christopher-Chair (708-283-3534)
Now let’s head off to the races with our
             latest CTPPs

				
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