The union representing 3,000 CN conductors has signed an agreement to continue running GO Transit trains even if they strike at 12:01 a.m. Saturday, when they enter a legal strike position.

But that does not mean more than 150,000 commuters who use the transit system every weekday have nothing to worry about. Under the agreement, union members have reserved an option to walk off the job entirely after three days notice, if they choose.

If that happens, the Toronto area inter-regional transit system will add a number of buses to the system to cover the routes, according to reports.

But GO chairman Peter Smith said buses will not be a complete solution to commuter headaches if GO trains stop rolling.

"Our customers are very intelligent people and they know there is no giant bus garage sitting north of Toronto that has 1,100 spare buses."

That is the number of buses GO Transit would need to keep all commuters moving on a typical day.

But Smith said he was thankful for the arrangement that will keep his trains rolling, at least in the short-term.

"We are so very, very thankful to the members of UTU who have agreed to maintain this service while their national union is striking over national issues," Smith said.

Six of GO's seven lines are operated by Canadian National Railway crews, with the Milton line being the only exception.

Smith said he "hopes both sides will continue to honour their agreement'' and noted commuters "don't need any more disruption.''

That was backed-up by commuters using GO trains on Friday.

"I think it's going to be absolutely going to be disastrous for all the commuters and it's going to be mayhem if it doesn't work out on Monday," one commuter told CTV's MairiAnna Bachynsky Friday morning.

Another man added that GO Trains are his way to commute to work in downtown Toronto.

"I can drive, but if there's a strike, you can't get a parking spot anyway," he said.

GO trains make 181 trips on weekdays and the majority of passengers are travelling in and out of downtown Toronto. GO Transit call centres have been flooded with questions about potential schedule interruptions, a spokesperson said.

The potential shut down comes as GO Transit has been struggling with recurring delays on major routes.

With reports from CTV's MairiAnna Bachynsky and Austin Delaney and files from The Canadian Press