FINAL
REPORT TO THE UNIVERSITY OF CALIFORNIA TRANSPORTATION CENTER
GRANT
UCTC - IA-65V430S: Amend#3
HOW
DOES TRAVEL BEHAVIOR CHANGE WHEN HOUSEHOLDS CHANGE JOBS?
William
A.V. Clark
UCLA Geography Department
1255 Bunche Hall
Los Angeles, CA 90095-1524
wclark@geog.ucla.edu
University
of California Los Angeles
FUNDED
BY A YEAR 14 RESEARCH GRANT
OVERVIEW AND
PROJECT PURPOSE
The
project continued the research in an earlier funded UCTC proposal - Does
Commuting Distance Matter? That research is being published in the Journal
of Regional Science and Urban Economics, 2002. The question posed in the
present research is whether households minimize the journey to work when they
change jobs but keep the residence constant. The research uses the same
panel study data set for the Seattle Metropolitan region that was used in the
previous research. The findings support the earlier findings on the impact of
changing residences. Overall, households, including two worker households,
attempt to minimize the distance between home and work when they change jobs.
Other things being equal they change jobs to reduce their commute times. The
impact of this finding is to reiterate the importance of the commute in
household decision making. Not unexpectedly, there are only minor changes in
mode choice - largely explained by the dominance of the automobile in commuting
in Seattle.
PROJECT BACKGROUND
Within the urban structure, the importance and assessment of accessibility grows more complex as the number of dispersed work centers increases and as the number of households with dual labor market attachments grows. There has been a rapid increase in the number of women in the workforce, many of them married and members of two-worker households. Women are the most dynamic supply sector of the labor market, and married women are an important component of spatial changes in the labor force, by virtue of their increased participation. In 1940, 28 percent of American women were in the labor force constituting one quarter of all workers. By 1997, female labor force participation had increased to 60 percent, constituting nearly half the labor force (US Bureau of Labor Statistics, 1998; Smith and Bachu, 1999). The number of wives in the paid labor force increased from 15.8 million (or 36.6% of all married couple families) in 1968 to 32.6 million (60.6%) in 1998 (Bureau of the Census and Current Population Survey, 1998). Of these 32.6 million working wives, more than a third were under 35 years of age and 56 percent had a least one minor child at home. Thus, understanding the decisions of dual worker households is a central element of understanding commuting behavior in increasingly dispersed metropolitan areas.
RESEARCH TASKS
The research focused on three hypotheses:
1. Job change, like residence changes, will tend to
reduce commutes though differentially for husbands and wives and variably across
the urban structure.
2. Total and individual time commuting will decrease
with a job change as will the length and time of linked wives commuting.
3. Do Husbands and wives make job choices that are in
similar sectors of the city and are the outcomes reinforcing employment nodes
outside of the central city?
DATA AND
METHODS
A
panel data set for the Puget Sound region (Seattle, Washington) was used to
test, empirically, the extent to which changes in jobs impact the commuting
distances and times of individuals and households. The data set is a
longitudinal sample of approximately 5400 households within the Seattle labor
market. Demographic and commute characteristics for each household member were
collected for the period 1989-1994. In addition, a sub-sample maintained a
travel diary. For the purposes of this study the important data is that on
residential location (tract and zipcode) destination of the workplace (tract and
zipcode) purpose of the trip, mode, time and distance of the trip.
KEY FINDINGS
All households do reduce commuting distances when they change jobs in a manner
very similar to the process we uncovered for household behavior when they
changed residences. The findings
indicate that two-worker households with greater separation between workplace
and residence make decreases in distance and time when they change jobs.
Overall, as other studies have shown, women commute shorter distances and are
more likely to minimize their commuting by changing jobs.
The
probability model and the k value estimates of the probability of adjusting the
commute downward are also similar to the findings from the behavior with respect
to residential shifts.
Analyzing
the results by the pre-job change separation reveals a distinct pattern in which
households with bigger separation before the job change almost always reduced
their commuting distance and time to the new work place. The breakpoints, that
is the distance or time at which more households reduced rather than increased
their commutes occur at about 16 miles for two worker households.
Generally, the households that increased their commutes were those that had short commutes, either in distance or time, before they changed jobs. For the very longest commutes before a job change there is clear evidence of a tendency to maintain or reduce the commute with the job change. A large number of households increase the commute time when they had relatively short commutes prior to changing jobs.
Overall,
travel behavior remains remarkably consistent in mode before and after a job
change. The primary dependence on automobile commuting indeed impacted the mode
choices such that there were very small shifts to other modes when households
changed jobs. Women did not significantly use public transport in their
commuting behavior in relation to job changes.
The
evidence on changes in job concentration is indeterminate in this research and
will require additional analyses. To this point the research suggests that two
worker households do not choose work locations in similar sections of the city.
REFERENCES
W.A.V.
Clark and Suzanne Withers, Disentangling the interaction of migration mobility
and labor-force participation. Presented at the
Western Regional Science Association Meetings. Monterrey, California,
February, 2002.
W.A.V.
Clark and Suzanne Withers, Do job locations matter? Manuscript in preparation.