It may be some time before Metro Transit riders can find out exactly when a bus is coming.

A tracking system designed to provide the exact time a bus arrives has been off-line since summer 2007 as upgrades are being made.

Riders can call a phone number at the bottom of every bus stop sign to find out when a bus is scheduled to leave its starting point, but the actual time may be different.

Natasha Hartling, a university student in Halifax, said she has seen bus times off by as much as 20 minutes.

"It can be a bit inaccurate and off, but I just don't rely on it," Hartling told CBC News.

Metro Transit has been upgrading the GoTime service by changing over old radio transmitters on the buses to GPS trackers.

Spokeswoman Lori Patterson said technicians are still testing the new transmitters, so it could be the end of summer before the system is up.

"With any major project there's always unexpected delays and difficulties, and so this project was no exception, as I mentioned, because it's fairly complicated," she said.

Patterson said the upgrade costs $5 million. But she said it will save money in the long run because the GPS system can easily adapt to new bus routes.