Not to pile on too much, I hope, but when I lived in low-rent districts in New York City,
"taking a car" was a colloquial phrase for using a car service (a very different
thing from a (much more expensive) taxi), and when you ask "how many people were
riding in the car", most people would not have counted the driver. I'm not sure
how far such a thing can be generalized, but it does raise the perpetual question of how
the ACS question wording intersects with the local language and community.
Jeremy Raw, P.E., AICP
Senior Modeling Systems Analyst | Transportation and Mobility Planning | Virginia DOT
jeremy.raw(a)vdot.virginia.gov | Desk: 804-786-0998 | Fax: 804-225-4785
From: ctpp-news-bounces(a)chrispy.net on behalf of Ken.Cervenka(a)dot.gov
Sent: Wed 3/3/2010 10:28 AM
Subject: RE: [CTPP] No Car but Drives to Work Alone
Not sure I can add anything more to the "list of possibilities" that
will be truly useful to the listserv readers, but it is at least worth
noting exactly how the ACS question about vehicles was asked:
-- How many automobiles, vans, and trucks of one-ton capacity or less
are kept at home for use by members of this household? (with choices of
none, 1, 2, 3, 4, 5, and 6 or more).
An examination of local household surveys (as well as transit rider
surveys) show all sorts of variations to capture a household's "number
of vehicles available," but here is just one recent example: "How many
working vehicles are available to your household?" The two questions
will in most cases result in the same answer, but there will always be
situations where that won't be the case.
What strikes me as a bit on the unusual side is that I am not aware of
any sufficiently-large "follow-up" survey that documents what a person
is REALLY trying to say when they note their household has no vehicles
but yet they drove alone. I have a vague recollection of some local HH
survey CATI scripts that have a built-in logic check that forces a
follow-up question whenever a person driving alone comes from a
household without any vehicles identified, but I don't recall seeing any
summaries that may provide some useful statistics.
Federal Transit Administration, Planning & Environment
[mailto:firstname.lastname@example.org] On Behalf Of Robert Campbell
Sent: Wednesday, March 03, 2010 9:41 AM
Subject: Re: [CTPP] No Car but Drive Alone to Work
I was wondering whether Cambridge, MA, might be something of an outlier
for stats, because of its large student population. Perhaps the
students are using "family" cars for their journey to work. It would be
interesting to see if other communities, which have much smaller
resident student populations, experience the same % of drivers in
Robert L. Campbell,
MTA Long Island Bus
[mailto:email@example.com] On Behalf Of Cook, Cliff
Sent: Wednesday, March 03, 2010 9:37 AM
Cc: Shulman, Adam
Subject: [CTPP] No Car but Drives to Work Alone
Thanks to all who responded. I've summarized, paraphrased and quoted
below possible reasons below and added a few comments as appropriate:
1. Other modes such as bicycling, motorcycles and motor scooters.
(I think these are covered by the data in 20068 ACS table B08141 so they
are not likely the source of the problem.)
2. Leased, not owned, autos treated not counted as vehicles "kept
for use by members of this household" (This would be a misinterpretation
of the ACS question but stranger things have happened. Other types of
respondent errors could be in play here as well.)
3. Problem with data imputed by the Census Bureau for
4. Using a company car on loan, a zip car a neighbors car, a
parent's car or another car sharing service. (ZipCar is popular in
Cambridge but I doubt that would cover too many people. Company cars
might explain some but again seems an unlikely explanation for almost
700 commutes out of 48,600. Garaging a car not registered in Cambridge
is difficult as we require a resident permit for on street parking and
off street parking spaces are few and expensive. Over 60% of the housing
stock is rentals, often with no dedicated parking space included in the
5. Non-standard work week such as travel to a conference. (This
might be a not insignificant source. I've always been surprised by the
number of local residents who JTW data shows as "commuting to work" in
6. Based on the 2009 NHTS, the ACS result seems reasonable. In the
2009 NHTS (weighted results), 12% of persons in zero-vehicle households
who travelled to work "last week", did so in a vehicle with one person
in it. This works out to be 500k people out of 4,260k.
7. This phenomenon shows up in NHTS as well and appears to be a
very real result of the fact that some share of folks used borrowed cars
for travel. It may be a young adult who doesn't own a car but has one
available from dad, folks renting, folks borrowing etc. In consumer
expenditure surveys non-car owning households also have non trival auto
related expenses for travel. It is not uncommon for non-car households
to travel more PMT in SOV than on transit. In consumer expenditure
surveys non-car owning households also have non trival auto related
expenses for travel.
Thanks to all for your help!
I'm hoping someone can help me address this question from a colleague.
He put together a table from the 2006-2008 ACS showing mode of journey
to work by vehicles owned and came up with surprisingly large numbers
who do not won a car yet drive alone to work. No doubt, there are a few
people who fit this category but my guess is that this largely is the
result of either people misunderstanding the question or some sort of
coding problem. Here is an excerpt from his email ( the Cambridge here
is Cambridge, Massachusetts):
I'm looking at ACS data and specifically at cities and percent workers
have no car available. From that I'm then looking to see how those
workers get to work.
The attached worksheet shows my work. What is strange is that it shows
for Cambridge that 6.6% of people without a car available drove alone to
work. The percent is similar to Boston. And NYC has 3.4% of workers
with No vehicles available driving alone to work.
So, the question is, how can someone without a vehicle drive to work
alone? Do you have any ideas on this? It could be someone doesn't own
a vehicle, but drives a friend's car to work. Or has no car of their
own, but uses a company car to get to work. But seems like a high
number for this.
Can anyone shed any light on this?
Planning Information Manager
Cambridge Community Development Dept.
Cambridge, MA. 02139
617/349-4656 FAX 617/349-4669 TTY 617/349-4621
email => ccook(a)cambridgema.gov
web site => <http://www.cambridgema.gov/~CDD/>
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