One in seven Metrobuses doesn't have the technology to alert riders to when it is arriving, and some operators don't turn on the technology that they do have, according to Metro documents.
The documents provided to the D.C. Council show 13 to 15 percent of Metrobuses don't have working systems to send the agency their locations.
Other buses -- less than 5 percent -- don't report their location because an employee doesn't follow proper procedure, the documents said.
That means that Metro's website and smartphone apps that use the data aren't able to predict arrival times for those buses -- creating what the agency calls "ghost buses" that show up unannounced.
"There are buses that don't show up [on an app] that show up in real life," said Kimberley Shults, who relies on Metrobus to get to work in Bethesda.
But Metro is working to fix the problem. Spokesman Dan Stessel said the agency is installing new technology in all buses that will be complete by midyear, fall at the latest.
The new technology will give all buses the power to alert the agency of their locations and will do so every 30 seconds instead of every two minutes, like they do now. The new system will use cellular data instead of radio to communicate.
"[Bus arrival predictions] will certainly improve," Stessel said. "When buses refresh every 30 seconds, you'll probably see an increase in accuracy and also a smaller margin for error."
For those buses that do report their locations, the bus predictions that Metro feeds to app-makers and its website are currently 90 percent accurate, Stessel said. That means that 90 percent of the predictions are within two minutes of the buses' actual arrival time.
The new technology also will mean that automated voice announcements and digital displays telling riders about the next stop will be standard on Metrobuses. The new components will automatically count the number of passengers on the bus, so Metro can plan bus service better, expanding service where buses are crowded, Stessel said.
News of the new technology comes just as the popular app NextBus DC relaunched as iCommute DC. The app stopped working in December, after its makers had a dispute with another company that provides bus information.