The transit only lane on King Street is now in effect.
That means the north curb lane of King, from Mary to New streets, are for buses only.
The start of the one year polit project was delayed by rain on Tuesday.
Ward 2 Councellor Jason Farr says enforcement will be phased in.
There will be an education period for drivers to let them get used to the new rules.
But in a few weeks, police will ticket drivers who try to use the transit only lane.
And he says the pilot project is still evolving and there could be some room to allow bikes to use the lane.