During the summer of 1997 the Marius Dufresnes bridge on Highway 117 required extensive repairs and the closing of the bridge during that summer. To help alleviate traffic problems as commuters attempted to find alternate routes a commuter train was proposed to run between Jean-Talon Station and Blainville. This service would see two inbound and one outbound train in the morning and two outbound and one inbound train in the evening starting on May 12, 1997.
The service started on May 12, 1997 with four 900 series STCUM gallery coaches and GP-9 locomotive 1310. Ridership on that first day was in the neighbourhood of 600 persons. In conjunction with this experimental train service the CIT Basses Laurentides was running busses from the Blainville and Ste-Therese stations to St-Jerome, Boisbriand and Bois-des-Fillion. The busses were free for holders of train tickets. The STCUM Trainbus 935 took passengers downtown via University and Rene-Levesque to terminate at the Guy-Concordia métro station.
The temporary train has been quite successful and has received the support of the municipalities. Service was first extended until the end of 1997 and then through the spring of 1998. It was announced that the train will continue until August 15, 2000 and it is now permanent.
As a result of technical problems which the STCUM were having with their low floor busses AMT announced that starting on January 18, 1999 that two trains each morning would run from Blainville to Windsor station and two afternoon trains would make the return trip.
While this service was to be temporary lasting at most one month to permit the STCUM to resolve its technical problems the service has proved popular and was increased to two trains each way during the morning and afternoon rush. Lucien L'Allier is now the main southern terminus for the line.
Rumours persist that the service will be extended north to St-Jerome. Initially the service into Lucien L'Allier station used the south junction lead to the Vaudreuil Subdivision from the Adirondack Subdivision. The north junction lead was restored to service and upgraded in the spring of 1999 to eliminate the need for the train to reverse direction and also shorten the schedule.
The southern terminus of the line is at Lucien L'Allier with stops at Jean-Talon, Henri-Bourassa, Saint-Martin, Ste-Rose, Rosemere, Ste-Therese and finally at the northern terminus of Blainville.