One Bus Away too far
posted at 4:24 pm on November 23, 2010 by Fausta Wertz
Leave it to government to leave you stranded.
As snow pounded Washington state and Seattle commuters waited for a bus, the iPod app failed because King County shut off the data feed that tracks bus locations.
Brian Ferris, who created the OneBusAway app explains,
In his blog post, Ferris notes that outdated technology on King County buses makes it especially difficult to track bus locations when weather turns nasty.
The position of each bus in Metro KC is not tracked with GPS, but rather with a decidedly lower-tech approach. Each bus is outfitted with a device that can radio the current odometer reading for the bus back to a server. If we know the odometer reading when the bus starts its route, we can periodically monitor the real-time odometer readings to determine how far along the route the bus has traveled. This gives us an estimate of position and from there, an estimate of how early or late a bus is. This is how http://mybus.org works and OneBusAway is just a fancy front-end to MyBus.
The problem comes with buses on adverse weather reroute, or any type of temporary reroute. When a bus goes on reroute, the physical route changes and the odometry calculation based on the original route used above is no longer accurate. In a perfect world, we would know when a bus is on reroute and adjust to its new route. Unfortunately, there is currently no automated way for handling this situation.
King County is “years away” from a GPS bus tracking system.
Your good-weather friends at King County, however, thank you for using public transit.
Cross-posted at Fausta’s blog