Regular readers likely recall that two of my favorite topics are mobility and public transportation. (Okay, and motor scooters, but they'll have to wait for another day.) When you stop and think about it, mobility and public transportation aren't necessarily dissimilar. Both use public thoroughfares to take you from one place to another, albeit one physically and the other virtually.

With this in mind, you can imagine how excited I get when the two intersect, like they do with OneBusAway -- a service that lets bus riders use a cell phone or computer to keep tabs on their bus. Why? Well, if you have to ask, then you probably haven't spent much time in bus shelters wondering when the #8 is due to arrive. And if you're in Seattle where Brian Ferris (a PhD candidate in computer science) and Kari Watkins (a doctoral student in civil engineering) live, you can be that a fair amount of this waiting time is in the rain.

To use OneBusAway, just dial 206-456-0609 anda the system prompts for your bus stop number, looks it up in a database of  current bus locations, and then tells you how long until your bus arrives. According to Watkins, who works on transportation issues, research shows that removing uncertainty cuts frustration.

"When people have to wait, they think that twice as much time is passing. So if you're standing at a bus stop for five minutes, you perceive that time to be 10 minutes," Watkins said. Knowing the wait time changes the situation. "If I know ahead of time, I can grab that cup of coffee and be back out in time to catch my bus. And that kind of information makes taking public transit so much more livable."

To date, Ferris has invested about $70 of his own money to buy the domain name and voice-generating software. The phone number connects to a free service that relays phone calls over the Internet. He programs the site in his spare time, maintains a OneBusAway blog and scans other blogs and Twitter feeds for people experiencing problems. He's gradually adding more features. For instance, December's snow storm left many stranded on Seattle street corners waiting for buses that never came. Over the Christmas break Ferris added a feature for canceled buses. And since the system is open source, other programmers are able to contribute. One contributor wrote a patch to let you view two different routes on the same computer screen, so if you live close to two routes you can load one page to see which bus will come first.

"I'm definitely looking for more collaborators," Ferris said.