Smart Card Data Analysis
Using the Chicago Transit Authority (CTA) as an example, Utsunomiya, Attanucci and
Wilson (2006) discuss the potential usage of and barriers to increased data availability after
smart card implementation in public transportation agencies, concluding that agencies need to
tailor their smart card implementation plan to make the most of the increased data availability
it offers and that smart card penetration as a fare payment method is the key to its effective use
for the analysis of passenger behavior. Bagchi and White (2004) examine three cases of smart
card implementation in bus networks in the United Kingdom. They find that the advantages of
smart card data include larger samples than existing data sources and the ability to analyze
travel behavior over longer periods, but there are also limitations, particularly in the case of
bus travel in which cards are only validated upon entry to the system (i.e., bus boarding).
Certain types of information such as journey purpose are absent from smart card data and
would have to be collected through other methods. Therefore, they conclude that smart card
data cannot replace existing survey methods for data collection but may complement them. In
addition, the authors estimate smart card turnover rates and trip rates per card, and infer the
proportion of all bus boardings to linked trips (i.e., with bus-bus transfers) in each network.
For the small areas covered by the cards in their study, Bagchi and White (2004) link together
two bus journey stages that begin within 30 minutes of each other as recorded by smart card
transactions, but assert that in larger cities a wider time window would be needed to identify
complete trips. They refer to a similar study for a larger city by Hoffman and O'Mahony
(2005) in which 90 minutes is used to link bus journey stages as recorded by magnetic stripe
electronic ticketing technology. However, the highest rate of interchange in the Hoffman and
O'Mahony (2005) study occurred between 18 and 28 minutes after boarding the first bus.
Bagchi & White (2004) find a typical implied ratio ofboardings to complete (linked) trips of
1.25 and Hoffman and O'Mahony (2005) find a similar ratio of 1.21. As a final example of
interchange identification based on time windows, Okamura, Zhang and Akimasa (2004, cited
in Trepannier and Chapleau 2006) define an interchange as two journey stages that are
provided by different operators and occur within 60 minutes at the same location. They use
this definition to analyze interchange wait time at major transit hubs.