A few months ago I took a look at a study out of Seattle that examined rider attitudes towards that city's bus-tracker system, just as Chicago was extending its system to 400 bus stops, finally opening it up to the non-smart-phone-enabled. An overwhelming 92 percent of respondents were "somewhat more satisfied" or "much more satisfied"; Steven Vance had more. Among the study's findings:

It has been shown that transit traveler information can result in a mode-shift to public transportation. This stems from the riders’ ability to feel more in control of their trip, including their time spent waiting and their perception of safety. Existing studies…have shown that the ability to determine when the next vehicle is coming brings travelers’ perception of wait time in line with the true time spent waiting. Transit users value knowing how long their wait is, or whether they have just missed the last bus. In addition, it has been found that providing real-time information significantly increases passenger feelings of safety.

Having been a CTA user since well before the advent of bus tracker, I was curious as to the first bit: the "mode-shift to public transportation." I figured that people took public transportation because it's cheaper and less stressful, and that tracking systems were merely a convenience—a worthy one, but not one that would cause "mode shifting" in any great number.

Turns out both are kind of right. Via Eric Jaffe of The Atlantic Cities, a new report suggests that the CTA's bus tracking has caused a mode-shift, if a small one:

To take account of other factors that might affect bus ridership, we also include data on unemployment levels, gas prices, local weather conditions, transit service attributes, and socioeconomic characteristics during the study period…. Based on a linear mixed model, we found that the provision of Bus Tracker service does increase CTA bus ridership, although the average increase is modest. Further, the study findings suggest that there are temporal variations of the ridership effects among the routes, with the “winning” routes more likely to have the technology implemented in the later phases of the overall “roll-out” period.

Modest? Yes: about a 1.8 to 2.2 percent increase in average weekday ridership. It's about what I'd expect from personal experience—most of the time I take public transportation anyway, but being able to time my arrivals and departures has probably shaved off a few car trips that I might have taken otherwise. But Jaffe is hopeful for the future:

It's also likely that its success rose as the technology became accessible to a wider range of people through additional platforms like text message and smartphone apps. If that's the case, one can expect the impact of real-time transit updates to increase as both familiarity with the program and mobile technology itself becomes more pervasive.

Metra? It's in the pipeline.

Photograph: jbracken (CC by 2.0)