The Société de transport de Montréal says it has work to do on the accuracy of its iBus system, which allows public transit users to find out when their bus is supposed to arrive in real time.

A beta version of iBus was released in 2017 with the promise of allowing Montrealers to make more informed decisions about when to head to a bus stop, rather than relying on the printed schedule.

After launching the full version last year, the STM now says tweaks are still needed.

"Yes, there are anomalies our experts are working on, and the synchronization between our website and applications is one of those," said spokesperson Amélie Régis.

The real-time information is available on the STM website and through the third-party apps Transit and Chrono. They have access to schedules and data from GPS systems installed in buses.

According to the co-founder of the Transit app, Guillaume Campagna, Montreal isn't the only city to have these problems.

His app, developed in Montreal, provides real-time transit information for cities around the world.

He estimates about 90 per cent of STM buses send information correctly.

As for the other 10 per cent, "sometimes, it's material problems: the GPS is there, but it does not work, sometimes it's just human problems — the person did not activate GPS at the right time," he said.

Commuter Xénia Reinach travels from Côte-des-Neiges to Nuns' Island multiple times per week.

She said she makes the trip to meet clients and often finds herself resorting to paying for a taxi because of incongruencies between the app and when the bus actually arrives.

"The colder it gets, the more patience is put to the test," she said.