Transit agencies and the University of Washington are spending $150,000 to keep the popular One Bus Away online application going 13 more months.

One Bus Away — created by former UW computer-science graduate student Brian Ferris and former UW civil-engineering student Kari Watkins — allows users to type in a favorite bus stop or route number, then learn how soon the next King County Metro and Pierce Transit vehicles will arrive, as well as Sound Transit buses in those two counties.

Travelers also can follow simple links to bus, ferry or rail schedules as well as route maps. The service is used an estimated 50,000 times a week.

Ferris earned his doctorate this year and moved to Zurich, where he designs transit applications for Google. From Switzerland, he updated the system for free when Metro changed several routes Oct. 1; UW continues to run the system on its servers.

"The goal is to make sure the service survives," said Mark Hallenbeck, director of the Washington State Transportation Center at UW. He said the service could be taken over by the transit agencies or perhaps replaced by a Google app.

The service, at www.Onebusaway.org, is free and available over iPhone, Android and Windows Phone devices and personal computers.

One weakness in the system is that arrival estimates are based on what time the bus passed a previous stop or signpost, as recorded by old King County Metro transponders and software. Any route deviations or severe traffic throws the figures out of whack, Hallenbeck said.

Metro will finish installing a more accurate global-positioning-satellite system on its buses next year.

A second weakness is that some transit agencies don't track real-time bus positions, so One Bus Away sometimes relies on scheduled arrival times.

Information is available for Metro, Sound Transit and Pierce Transit (which are contributing toward the $150,000), as well as Community Transit, King County Water Taxi, Intercity Transit of Thurston County, Seattle Children's shuttles, Washington State Ferries and the Seattle streetcar.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com