We (the royal “we”) are interested in personal
travel patterns, for a variety of transportation planning applications. The
CTPP program will provide home-to-work origin-destination tables using multiple
years of surveys from the American Community Survey. But, other data
sources should be examined for their potential to augment the CTPP, for small
area origin-destination matrices. For example, many of you are aware of
my interest in using multi-day GPS. Each data source, including ACS
and the CTPP, has its own benefits and limitations. One of the datasets
of interest is the LEHD OntheMap “home-to-work” flows.
We would like to encourage more analysis and evaluation of
the LEHD OnTheMap data. While
the LEHD OnTheMap interface is a user-friendly web-based software http://lehd.did.census.gov/led/
, we believe that transportation planners will be more interested in the
potential of the synthetic block data records (10 implicates are created in the
data synthesis process) to examine the origin/destination flow results. These
data are available for download on the
I asked Laura McWethy at Cambridge
Systematics to prepare
some documentation on the files, to make it easier
for others to examine this data. It is attached.
Caveats:
The files are large since they represent
block-to-block pairs.
The data are synthetic. This is the first
synthetic data product approved by the Census Bureau’s Disclosure Review
Board. Data synthesis is used to protect individual confidentiality.
The universe of workers (workers covered by
unemployment insurance) differs from “all workers”
You should take the time to understand the data
sources and synthetic data processes used to generate these results.
We are interested in your tests of the LEHD OnTheMap block
level data. I hope that Nathan Erlbaum and Aaron Westcott of New York
State DOT will share the results of their work on county-to-county flows.
Introductory material on LEHD OnTheMap is available through a
recorded presentation from the TRB Planning Applications conference in
Elaine Murakami
FHWA Office of Planning (
206-220-4460 (in