The Toronto Pan Am transportation plan calls for a 150-kilometre-long continuous network of high occupancy vehicle lanes from Hamilton to Oshawa, incorporating existing HOV lanes on the Queen Elizabeth Way and Highway 404.
"These HOV lanes are going to pop up pretty quickly on people who aren't used to seeing them, and I don't see much of an education plan or much of an enforcement plan," said Progressive Conservative critic Rod Jackson.
"I see traffic chaos happening during the Pan Am Games with this sort of plan."
Active traffic lanes will be taken out of commission on Highways 400, 401, 427, other parts of the QEW, the Don Valley Parkway and the Gardiner Expressway to create the temporary HOV lanes, which will be open to other cars and trucks with passengers.
However, provincial officials could not say yet if the live traffic lanes on some of the most congested highways in Canada will be blocked to other traffic around the clock for the duration of the games, or only on an as-needed basis.
Tourism and Sport Minister Michael Chan said voluntary measures to convince drivers to use public transit during the Pan and ParaPan Am Games could reduce traffic by 20 per cent, something Olympic host cities were successful with.
"Based on best practices of past games, we are very confident that this 20 per cent target is achievable," said Chan. "The past experience in Vancouver and also in London actually achieved 30-to-40 per cent (traffic reductions)."
But the Conservatives said "it's absolutely unrealistic" to plan for less traffic when 250,000 visitors are expected to attend the Games, along with 10,000 athletes and officials, 20,000 volunteers and 4,400 accredited media.
"I think they should be banking on a 20 per cent increase, even if it's just to get ready for the worst-case scenario," said Jackson.
"It's actually naive and frankly somewhat absurd to think that there's going to be a 20 per cent decrease based on the hope that people will do the right thing and stay out of their cars."
Officials who briefed reporters on background said there would be other measures to reduce traffic such as encouraging businesses to get deliveries at off-peak hours and mobile phone apps to help people determine the best routes to use during the Games.
The transportation plan also includes so-called priority lanes for Pan Am vehicles on highways and some city streets to get to competition sites, including a proposed lane on Jarvis St. in downtown Toronto to get to and from the old Maple Leaf Gardens.
The transportation budget for the games is $75-to-90 million, about half of the amount used for transportation at the Vancouver Olympics.
The total budget for the Games is now estimated at $2.5 billion, and officials said Friday they are on time and slightly under budget at this point.
The 2015 Pan Am Games will take place at 34 different competition venues across southern Ontario, from Niagara in the south to as far north as Orillia, and officials warned parking will be "severely restricted or non-existent" at many of the sites.
The Games run from July 7 to 26, followed by the Parapan Am Games Aug. 7 to 15.