The Réseau express métropolitain (REM), the massive light rail project whose first line, a connection between the South Shore to downtown Montreal, opens this weekend and will be free for the first two days.

But as of 1 p.m. Saturday, REM staff began turning away new passengers hoping to board the train for the first time so people already on board could return to their departure point.

Anyone who didn't get a chance to try the train for free Saturday is invited to line up at one of the five stations — Brossard, Du Quartier, Panama, Île-des-Sœurs and Gare Centrale — Sunday between 9 a.m. and 7 p.m.

The driverless trains have been running along the full length of the tracks which are scheduled to become fully operational on Monday.

CDPQ Infra, a subsidiary of Quebec's pension fund manager the Caisse de dépôt et placement du Québec, is conducting tests.

But the agency wants users to get on board, both to stir up hype so people are more inclined to take the REM when it becomes fully operational and to iron out any final kinks.

As of Monday, July 31, users will have to pay a fare to board a train.

The ARTM says users can access the REM stations by foot, bike, car or Metro for the Gare Centrale station, which is steps away from the Bonaventure Metro station on the Orange line.

It's expected to be a party, of sorts, according to the ARTM. Near the Gare Centrale station, there will be music, treats and other surprises to mark the REM's first day.

The REM has been in the works since 2015. It is the largest public transit project in Quebec in decades.

WATCH | Here's how to ride the REM:

Media Video | CBC News Montreal : A beginner’s guide to riding Montreal's REM

Caption: The hype is real. It’s finally here. Watch this before hopping on board.

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