Summary and Future Research
Through the observation of 83 prospective passengers waiting at bus stops, the
relationship between perceived and actual waiting times was investigated. The
results of estimating a linear relationship between the two variables indicate that,
while the intercept is significantly greater than 0, the slope’s equality to 1 cannot
be rejected. This finding implies that the data do not reveal evidence that the
additional perceived waiting time varies with the actual time within the range of 3
to 15 minutes reflected in the data set. Moreover, some socioeconomic variables
are found to have explanatory value. In particular, a passenger’s walking time to
the destination from the bus stop at which he or she is waiting and the presence
of a time constraint reflect an impact on the perceived waiting time. A longer
walking time produces a greater exaggeration in the perceived waiting time, while
the presence of a time constraint brings the perceived waiting time closer to the
actual time.
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The mean difference between the perceived waiting time by passengers and the
actual time is 0.84 minutes. This additional time is related to both an equivalent
savings in vehicle-hours per day and an equivalent coefficient of variation (the
ratio of the standard deviation to the mean) in the headway of a route. These relationships
are developed in an effort to assess the benefits of eliminating the exaggeration
in passengers’ perceptions of waiting time by providing accurate realtime
passenger information on the time until the next bus arrival. If the additional
amount of time—eliminated by the provision of real-time information—is used to
increase the headway to a value such that the mean passenger perceived waiting
time remains unchanged, the reduction in the vehicles-hours per day required to
provide service is derived assuming a deterministic headway and totally random
passenger arrivals. For a running time of 30 minutes, a headway of 10 minutes, and
a duration of service of 18 hours per day, a reduction of 7.77 vehicle-hours per day
is achieved, amounting to a 14.4 percent saving.
If the additional 0.84 minutes of perceived time is added to the expected waiting
time of a passenger waiting for a bus when there is no variation in the headway and
assuming totally random passenger arrivals, the equivalent headway coefficient of
variation CV[h] producing such an additional waiting time is derived. For a mean
headway of 10 minutes, CV[h] is 0.410 reflecting a standard deviation of 4.10. Thus,
providing real-time information at bus stops—for example, via VMSs—could
reduce passengers’ mean perceived waiting time by an amount equivalent to
that achieved through eliminating the corresponding standard deviation in the
headway.
Because passengers perceive waiting times to be greater than actual waiting times
at a bus stop, real-time passenger information systems could potentially reduce
the perceived waiting time for buses when providing accurate information. The
reduction in perceived waiting times could potentially be translated into reduced
operating costs or increased passenger satisfaction and, ultimately, into increased
ridership for public transit, depending on the policies adopted by the transit
agency in conjunction with the introduction of real-time passenger information
systems.
This study demonstrated the feasibility of examining the questions of interest and
points to several directions regarding future research. Based on this pilot study,
there is good evidence that a difference between perceived and actual waiting
times does exist to motivate a more comprehensive data collection and modeling
effort. It would be valuable to observe passengers traveling on larger transit sys-
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tems than the university campus-based system of this study. Larger systems present
additional complexity in service that might affect waiting time perceptions
(e.g., while waiting during transfers between routes, and when traveling on longer
routes) and reflect a more heterogeneous traveling population. A wider range of
actual waiting times is also important to allow for testing various specifications
characterizing the relationship between perceived and actual waiting times. Moreover,
a larger data set with more complete observations of socioeconomic variables
is necessary, given the indication that such variables could have an important
impact on the perceptions of waiting time. Also, additional socioeconomic variables
might influence the perceptions of waiting time and, hence, would be worth
observing. Such variables include time of day, whether the passenger has access
to time-telling devices other than a watch (e.g., mobile phone, other portable
electronics, or public clocks visible from the bus stop), whether the passenger
is traveling with a group, and whether a bus operating on a route that does not
provide service to