Hi Charles,

 

I appreciate your response. After speaking with other folk, now I understand how everything works. To answer my initial question myself, it seems that CTPP is able to get the lower/smaller/lowest level data from Census Bureau, which is not the same one open to public on Census Bureau website, and then aggregate it to TAZ level. Originally I was thinking everyone was getting the same dataset. Problem solved.

 

Thanks!

 

Best,

Xinbo Mi

 

 

From: Charles Purvis <clpurvis@att.net>
Sent: Friday, August 6, 2021 5:05 PM
To: CTPP ListServe <ctpp-news@mailman.chrispy.net>
Subject: [CTPP] Re: CTPP TAZ Data

 

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Xinbo:

 

You are correct that the TAZ (and TAD) data are not available directly through the Census Bureau’s website. The TAZ/TAD data is only available through the CTPP data site:

 

http://data5.ctpp.transportation.org/ctpp1216/

 

But the data is literally available to everyone. It’s open to the public. I’m certain that AASHTO, USDOT, the Census Bureau, the State DOTs and MPOs would encourage their use by government staff, academics, consultants, journalists and interested citizens. 

 

The CTPP data is also summarized at standard census geography levels: state, county, place, PUMA, census tract, MSA.

 

There is a lot of  background material on the CTPP for you and others to peruse:

 

https://www.fhwa.dot.gov/planning/census_issues/ctpp/index.cfm

 

https://ctpp.transportation.org/

 

https://ctpp.transportation.org/ctpp-history/

 

http://trbcensus.com/

 

Chuck

 

 



On Aug 5, 2021, at 2:26 PM, Mi, Xinbo <xmi@evansvillempo.com> wrote:

 

Thanks for your information. However, the TAZ level ACS data could not be found on its website (https://data.census.gov/cedsci/advanced). When you said “The data crunching and table production was done inside the Census Bureau.”, did you mean Census Bureau still processed data at TAZ level and gave it to CTPP but not open to public? I am a bit confused here because it is said on census.gov that “In the ACS, block groups are the lowest (smallest) level of geography published. Block group data are only available in the ACS 5-year data products.”

 

Best, 

Xinbo Mi

 

From: Ed Christopher <edc@berwyned.com> 
Sent: Thursday, August 5, 2021 3:27 PM
To: CTPP ListServe <ctpp-news@mailman.chrispy.net>; Mi, Xinbo <xmi@evansvillempo.com>
Subject: [CTPP] Re: CTPP TAZ Data

 

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1. TAZs were defined by the MPOs and states using basically a census block to TAZ equivalency. The data crunching and table production was done inside the Census Bureau.

2. This will all depend on what CTPP gets but it will be census geography. I believe the ask from the Census Bureau is for block group and tract level data, which likely has some relationship to the TDM tazs, but the Census Bureau disclosure review board needs to complete their review first before all the table details are know.   

On 8/5/2021 2:58 PM, Mi, Xinbo wrote:

Hi, 

 

I am new to the list and I want to post 2 questions: 

 

1.       Since CTPP data is based on ACS data and the lowest level of geography of ACS data is block groups, how was CTPP data generated at TAZ level?

2.       Since TAZ level CTPP data will be discontinued, what will be the best practice to get TAZ level demographic, socioeconomic and housing characteristics data as input layers to travel demand model?

 

Thanks! 

 

Best,

Xinbo Mi

Transportation Engineer 

Evansville Metropolitan Planning Organization

1NW Martin Luther King Jr. Blvd. Room 316

Evansville, Indiana 47708

Office Main Line 812.436.7833

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-- 
Ed Christopher
Transportation Planning Consultant
708-269-5237

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