Based on information obtained from the Société des Transports de Montréal (STM), the new West Island express buses often travel with about 35 empty seats.
The STM vice-chair Marvin Rotrand says he suspects some commuters aren't aware of the routes.
Rotrand is considering an awareness campaign to make riders more familiar.
"There are people getting on at Lionel-Groulx to go to the west island on a route that has many stops versus the 405 that has few stops," said Rotrand.
Sainte-Anne-de-Bellevue resident Talia Sinagra said the new 405 bus saves her up to two hours a day on her commute downtown. But she wonders if West Island residents know about the new buses.
"I guess probably not because I see a lot of people on the 211 bus, which goes the same way, but it takes longer."
The transit corporation said the new buses were intended to ease congestion when work begins on the Turcot Interchange.
The busy highway will be rebuilt over the next six years and will make room for more green space and bus lanes.
Some users frustrated with "inconsistent" service
Some users told the CBC they are getting increasingly frustrated with "inconsistent" schedules for the STM's new express bus service.
"Usually, three times out of five they just don't show up," said a commuter. "They don't always come on time. It's pretty inconsistent. I guess it's poorly planned."
Rotrand, said the STM is working closely with the Agence métropolitaine de transport (AMT) to synchronize schedules and increase the frequency of buses and trains.