Electronic ETAs

In Seattle, riders can find out when the next bus will arrive using their Web-enabled mobile phones. The service is the latest high-tech transit application from King County Metro Transit and the University of Washingtons Intelligent Transportation Systems (ITS) Research Program. Riders have been using desktop computers to check up-to-the-minute schedules and arrival times on the Web for more than 1,000 area buses since last year. The mobile phone service uses the same software application, but in a stripped down form that fits information on small screens.

"The purpose is to help people make informed travel decisions," said Stuart Maclean, a researcher with the ITS group and the author of the cell phone software application. "Even if you know your bus is going to be late, it helps to know how late, especially when youre standing at a stop in the rain. And it rains a lot in Seattle."

The U.S. Department of Transportation has focused most of its resources in intelligent transportation technology, made available through research grants, on improving the plight of congested highways. But lately, under pressure from environmentalists and local officials, more attention has been aimed at improving public transit through technology. Seattle and King County were early pioneers in using ITS and have been tracking buses to better manage their fleet.

By visiting the Web site , riders can find out the estimated time a bus will reach a certain point. The times are actually predictions based on a number of factors. First, equipment on board each bus transmits odometer readings to a central computer on a minute-by-minute basis. Embedded road sensors around the city report traffic flow to the same computer, which then uses an algorithm to calculate when the bus will arrive at a certain point. This information is then converted into a digital image, which appears on the MyBus Web site.

Every day, the system calculates 200,000 bus arrival estimations, according to Maclean. The Web service receives more than 2.4 million hits every month from interested bus riders. The newer, wireless service receives about 3,500 hits per month and interest continues to grow.

Making the Rounds

MyBus doesnt use GPS to calculate the location of Seattle buses. Maclean described GPS as expensive for bus tracking and said the GPS signals can sometimes give off false readings in built-up areas, such as downtown Seattle.

But despite its potential limitations, using GPS to track buses is growing in popularity in the United States and around the world. A number of city transit agencies have begun using the services of NextBus Information Systems Inc., which deploys GPS and modeling software to predict bus locations. San Francisco, Emeryville, Glendale and Santa Barbara, Calif., are using NextBus. Similar services are being rolled out in Vail, Colo., Fairfax and Arlington counties, Va., Rehoboth, Del., and Oklahoma City later this year. Boston, with the oldest transit system in the country, also uses NextBus on some of its bus routes.

NextBus equips each bus with a GPS receiver, a CDPD modem and an antenna. Bus location information is transmitted to an information center where it is merged with data about intended stops and known traffic conditions and fed into a predictive software program to calculate arrival time. The information is then sent out over the Web and to wireless bus stop and shelter displays. The signs also can be used in malls, stores and restaurants. (Imagine