The importance of human effort in planning networks

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The importance of human effort in planning
networks
Dr John Parkin Reader in Transport Engineering
Planning j.parkin_at_bolton.ac.uk
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• 1 Effort the forgotten component
• 2 The effort of cycling
• 3 Hypotheses concerning effort
• The experiment
• 5 The application
• 6 Implications

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1 Effort the forgotten component

• Transport models traditionally based on utility.
• Recent have included activity based approaches
  and social psychological approaches.
• Motive power for cycling and walking provided by
  the traveller.
• But effort has received scant attention in any
  modelling paradigm, despite it being an easily
  measurable cost.
• Observations are used to model the effort of
  cycling to identify energy consumption.

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2 The effort of cycling
where W power (w) Cv
speed of the bicycle (m/s) ?mech
mechanical efficiency of the bicycle ?m
mass of rider and machine (kg) g
acceleration due to gravity (m/s2) Cr
coefficient of rolling resistance s
gradient () a acceleration of
the bicycle (m/s2) mw effective
rotational mass of the wheels and the tyres
(kg) CD aerodynamic drag
coefficient A frontal area of rider
and machine (m2) ? density of air
(kg/m3) Cw headwind (m/s)
Main source Whitt, F.R. and Wilson, D.G. (1982)
Bicycling Science. 2nd Edition. The MIT Press.
Cambridge, Massachusetts.
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Pictorial representation of gradient effect
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Pictorial representation of stops effect
2 stops per kilometre
4 kilometres
6 stops per kilometre
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3 Hypotheses concerning effort

• For starts
• Hypothesis 1 the cyclist maintains a constant
  acceleration until normal cruising speed is
  reached. This would require additional energy
  relative to the case with no pauses and, as the
  average power output is therefore higher, would
  create additional stress and heat to the point of
  discomfort.
• Hypothesis 2 the cyclists average power output
  during the journey is the same as if the cyclist
  maintained normal cruising speed throughout, this
  results in a cruising speed less than would be
  the case without pauses.
• Hypothesis 3 power output is constant so that
  normal cruising speed is reached asymptotically.
• Graham (1998)

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• For hills
• 1 Increase power to above normal and maintain
  speed at some level less than normal flat
  gradient speed.
• 2 As (1), but reduce additional power over time
  depending on hill length and gradient.
• 3 Maintain power output as on the flat, hence
  speed reduces to new lower constant.

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4 The experiment

• Time-stamped x, y and z coordinates
• 16 volunteers (four female)
• 100 minutes of commuting data
• Summer 2008 in Leeds, UK
• 38 aged 30 and under
• 16 were aged over 50
• The types of bicycle used included touring (6),
  mountain (5), town/city (5), folding (1) and
  racing (1) bicycles.
• All bar one either experienced or very
  experienced
• 13 had either frequent or very frequent recent
  cycling activity.

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5 The application
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6 Implications

• Effort and time
• Gradients have a significantly disproportionate
  effect on total energy consumption as compared
  with their effect on journey time. Junctions
  requiring a stop serve to increase total energy
  consumption on a typical urban journey by as much
  as 10.
• Hence, effort varies significantly and in a way
  independent of journey time
• Hence, effort is a factor which needs to be
  considered in planning and engineering for cycle
  traffic.

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• On the one hand
• All that is required to calculate the metrics
  presented are link length, height differences
  across the link, and whether or not there is a
  stop required at the upstream end of the link.
• On the other hand
• Added sophistication could include different
  rolling resistances, average prevailing wind
  conditions, and probabilities of being stopped at
  junctions and other points of dislocation in the
  journey.

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• Also
• Behavioural perception of the effort required to
  cycle may not vary linearly with an objectively
  determined measure of effort.
• Important to balance the perceived disutility of
  energy required for a journey against the
  ambience of the journey.
• Finally
• Interchanges require effort (to carry, park,
  pack, unpack etc.) and energy requirements of
  interchange may provide a good measure of the
  disutility of interchange.

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