Could you also have made this trip by another mode

1
Could you also have made this trip by another
mode?

• On perceptions of alternative travel
  opportunities of car and rail travellers in the
  Amsterdam region
• Piet Rietveld
• Job van Exel

2
Figure 1 Study area and sample size
Source adapted from Ministry of Transport (2001)
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Rational choice

• Consider the complete choice set
• Judge every alternative in the choice set by
  means of a utility function ( generalized cost
  function)
• Select the best alternative
• Standard analytical tool to estimate utility
  function is the logit model (random utility)

4
There may be a gap between objective and
subjective choice set

• Objective choice set all travel alternatives
  implied by a certain origin-destination
  combination ( or activity pattern)
• Subjective choice set subset of objective choice
  set, according to
• Awareness (traveller should be aware of
  alternative)
• Feasibility, acceptability.
• Possibly based on subjectively determined data

5
Most modelers ignore the possible gap between
objective and subjective choice set

• Is this a serious problem?
• May be not when the ignored alternatives are
  the least attractive ones
• and
• May be not when misperceptions are not systematic

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Long distance trips towards Amsterdam, 2000, case
study

• Rijkswaterstaat (North Holland)
• Public transport travellers
• 41,000 questionnaires distributed in trains
• 9,900 were returned (24)
• 7,950 were useful
• Car travellers
• 70,000 licence plates observed, received a
  questionnaire
• 23,000 were returned (33)
• 19,200 were useful

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Table 1 Characteristics train travellers (N7,950)
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Figure 2 Car in objective choice-set?

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Train users with car in choice setCould you also
have made this trip by car?

• Yes, mostly do 6
• Yes, sometimes do 66
• No 28
• Conclusion most train users sometimes use the
  car for their commuting trip.
• Specific nature of the Yes, mostly do group.
• Car in garage, follow-up activity after work,

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Figure 3 Main reasons for choosing public
transport instead of car among public transport
travellers with car in their choice-set (n3,540)
Note more than one response possible
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Multinomial logit model

• Ordered probit did not work well boundary
  parameters were sometimes negative.
• Multinomial logit
• Presentation in terms of elasticities in stead
  of original parameters because the latter are
  difficult to interpret.

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Table 2 Multinomial regression results
possibility to use car among train travellers
with car in choice-set for this trip (N3,540)
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Table 3 Characteristics car travellers (N19,232)
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Table 4 Possibility to use public transport among
car travellers (N19,232)
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Implications for mobility management

• Institutional barriers in the fields of
• Business travel
• Car ownership
• Who pays for trip
• Prevent the consideration of public transport

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Relationship between objective and subjective
travel times in public transport seen by car
users

• Objective public transport travel time100
• Subjective public transport travel time146
• Objective PT travel time/actual car travel time
  1.6
• Subjective PT travel time/actual car travel time
  2.3

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Implications for inclusion of PT in choice set of
car users

• Replace subjective PT travel time by objective PT
  travel time
• Then prob of (I could not have made this trip by
  PT) declines from 51 to 20
• Whether this would have lead to actual change in
  behaviour cannot be said, however.

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Provisos

• How to measure objective travel time
• Does include frequency aspects
• Deviant perceptions result from
• Lack of knowledge, or
• Justification behaviour