J. L. MWAKALONGE ET AL. 295
In general, high-income households made few non-
ing land use vari
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port Card, Sann, Cascade Bicycle
Club, and Chieration Transporta-
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motorized trips in 1990 and 1995. However, the trend
changed in 2001 and 2009 for this group, with an in-
crease in non-motorized trips. Persons aged 50 and
over showed an increased demand for non-motorized
travel, whereas children aged 0 - 15 showed a de-
creasing preference for non-motorized travel over time.
With the exception of Lifecycle 2, 3, and 5, all the
household structures showed an increasing demand in
non-motorized travel over time.
Change in the composition of households was reflec-
ted in an increase in the number of workers per
household, an increase in the number of vehicles per
worker, and a decrease in the household size.
With the exception of 2009, there was an increase in
the average total number of trips made per household,
notwithstanding the decline in average household size.
This suggests that changes in the socioeconomic
structure of households and lifestyle changes were in-
fluential factors in the increase in trips.
The empirical investigation on the temporal transfer-
ability of non-motorized and total trip generation models
yielded the following findings:
The increase in vehicle ownership impacted the de-
mand for non-motorized travel negatively. However,
further analysis is required to identify the level of in-
ter-relationship between the number of vehicles owned
and the number of non-motorized trips made for a
For non-motorized travel, only the coefficient for sin-
gle-adult households with no children was stable
across all of the analysis years. For both non-moto-
rized and total travel, most model parameter estimates
were stable short term but not long term.
With respect to the models’ transferability to 2009,
the 2001 model predicted travel better than the 1990
and 1995 models. Further, the models’ ability to pre-
dict travel in future contexts decreased with increas-
ing time between estimation and application contexts.
This indicates the inability of a model to capture large
changes in urban structure and travel behavior.
In general, in all analysis years, the total travel mo-
dels transferred better than non-motorized models.
In general, despite not finding universal stability in
model parameter estimates, the models were marginally
able to replicate travel in 2009 relative to the locally es-
timated 2009 model. This study gives a general picture of
the temporal transferability of non-motorized travel com-
pared to total travel using the available national datasets.
More research is required, particularly at the regional
level, to understand a region’s specific changes in land
use and travel behavior and their influence on non-mo-
rized travel. Further, well-specified models incorporat-
ables may be appropriate where the data
are available to improve models’ ability to explain varia-
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