STABILITY OF TRAVEL TIME EXPENDITUREAN EXPLANATION FROM BIOLOGICAL
POINT OF VIEW
Asif Ahmed
Peter Stopher
PhD Student
Professor, Transport
Planning
Institute of Transport and Logistics Studies (ITLS)
Background & Introduction
› TTB refers to stable (1-1.5 hours per day) amount of time spent on travelling.
National Travel Surveys,
UK 1972/73 to 2005
Travel time budget, h/cap/d
› Invariant with space and time
* Open circle uses most accurate CATTI & Travel Diary
Daily distance travelled, km/cap/d
› No analytical evidence found to answer why such stability?
Source: Schafer, A. 2000, "Regularities in Travel Demand: An International Perspective", J. Transportation Statistics, vol.3, no. 3, pp. 1-31.
2
Biological Basis for Stability
The concept of energy expenditure (MET) is described as the
“…biological basis of physical activity…” It implies “…an
inherent control centre within the central nervous system that
regulates one’s daily energy expenditure with motor activity…”
and, like other biological regulators, such “…an intrinsic activity
centre should be expected to regulate the amount of daily
physical activity to a particular set level…” (Rowland, 1998).
“…both human and animal studies indicate that SPA, and
the resultant energy expenditure (NEAT) are inherent…”
and, “biologically regulated” (Garland et al., 2011).
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Data & Method
•South Australian Panel 50 hh, 4-weeks Personalised GPS travel survey in
two waves in July and November 2005
•Data are cleaned using extensive manual
map editing and software tools
•Processed GPS travel data then used to
identify travel mode by using the “mode
detection software” developed by ITLS.
•Energy Expenditure on travel is then
estimated by using the travel time data
(collected by GPS device) and mode
specific energy expenditure coefficient.
Data from
GPS
Device
TI
processing
EE
(KJ/m)
Car, roads
4.2
Car2
13.4
Walk
14.1
Cycling
14.7
Standing r/h
6.7
Sitting
1.5
standing
2.6
Map Editing
Post Map
Editing
•Research if any stability in energy
expenditure on travel is obtained
•Analyse the relationship between Energy
Expenditure and Travel Time at an
individual level
Activity1
Cleaned Data
1Measured
average values of energy consumption per unit time for
different kinds of activities.(Source: Kolbl and Helbing, 2003 pp 48.4)
2Car travel in peak hour
4
Thank You
Q & A?
Email : A.Ahmed@itls.usyd.edu.au
References
Metz, D. 2008, "The Myth of Travel Time Saving", Transport Reviews, vol.28, no. 3, pp. 321336.
Ausubel J H and Marchetti C (2001) “The Evolution of Transport”, The Industrial Physicist7(2):
20-24
Schafer, A. 2000, "Regularities in Travel Demand: An International Perspective", Journal of
Transportation Statistics, vol.3, no. 3, pp. 1-31.
Rowland, T. W. 1998, "The biological basis of physical activity", Medicine & Science in Sports
& Exercise, vol.30, no. 3, pp. 392-399.
Garland, T., Schutz, H., Chappell, M. A., Keeney, B. K., Meek, T. H., Copes, L. E., Acosta,
W., Drenowatz, C., Maciel, R. C., van Dijk, G., Kotz, C. M. and Eisenmann, J. C. 2011, "The
biological control of voluntary exercise, spontaneous physical activity and daily energy
expenditure in relation to obesity: human and rodent perspectives", Journal of Experimental
Biology Journal of Experimental Biology, vol.214, no. 2, pp. 206-229.
Wilkin TJ (2011) “Pediatric Debate: Can we modulate physical activity in children? No”,
International Journal of Obesity, 35,1270-1276.
Kolbl, R. and Helbing, D. 2003, "Energy laws in human travel behaviour", New
Journal of Physics, vol.5, no. 48.1–48.12.