New research is showing that providing real-time bus arrival information to transit riders will increase ridership for that transit agency - though just modestly - by about 2 percent.
Researchers in the June issue of Transportation Research Part C looked at CTA ridership numbers for select routes after the introduction of Bus Tracker and concluded that Bus Tracker certainly serves to retain existing passengers, and also attract new ones:
This finding suggests that marketing strategies for real-time information should be targeted not only to transit users but also to transit non-users in order to bring about larger increase in transit ridership. Furthermore, since one major purpose of providing real-time transit information is to increase transit mode share and attract transit non-users, greater effort is needed to promote this system among those transit non-users.
A summary of the study in The Atlantic notes that the study authors were able to control for "influential ridership factors like unemployment levels, gas prices, weather, transit service attributes, socioeconomic characteristics, and typical monthly fluctuations."
Related to this story is this Xconomy report about how Google Transit is reshaping how we plan trips on public transportation. While Google doesn't have real-time information, it does have the schedules for 475 transit agencies worldwide, and can map your trip for you and tell you fairly accurately how long it will take.
I use Google Transit exclusively when I have to go somewhere new on the CTA. Its margin of error on departure times is less than five minutes. But I don't use it for that. I use it to determine how long it will take to get to my destination so I know what time I have to leave.
Now THAT is useful information.