Eastbound morning commutes on the Gardiner would increase by an agonizing 10 minutes between Park Lawn Rd. and the east end of the expressway.

Traffic congestion, if the Gardiner is torn down east of Jarvis St., would also cost $36.6 million annually in lost productivity and divert about 1,600 cars a day from the Don Valley Parkway onto Richmond St.

Those are among the findings of a study by the University of Toronto’s Centre for Intelligent Transportation Systems, commissioned by the Gardiner Coalition, a group that includes the CAA South Central Ontario and the Toronto Financial Business Improvement Area.

The report, being released Thursday, comes a week before the city’s public works committee tackles the difficult question of what to do about the deteriorating, relatively lightly travelled stretch of the Gardiner east of Jarvis.

The coalition would like the city to opt for the more expensive option of maintaining a direct link between the expressway and the DVP.

Its study suggests that the traffic implications of doing away with the elevated 2.4-km stretch would extend well beyond the Gardiner itself and that westbound commutes would also increase by up to six and half minutes.

The times, which are substantially longer than the two to three additional minutes (depending on the route) predicted by a study done by city staff and Waterfront Toronto, are conservative, said the CAA’s Elliott Silverstein, who called them a “best-case scenario.”

“Lane reductions, construction, accidents, inclement weather also play into it,” he said.

Completely tearing down the road would cost about $416 million, according to the city. The so-called “hybrid” option that would still connect east-end Gardiner drivers to the DVP is estimated to cost more than twice as much, $919 million. But that’s the coalition’s preference, given that the third option — maintaining the existing structure — appears to have fallen off the table.

The eight-lane boulevard that would replace the elevated expressway if it’s torn down, which would see significant truck traffic, also presents a significant pedestrian barrier to the waterfront, added Silverstein.

The coalition is not trying to discredit other studies of the Gardiner, including those by Waterfront Toronto, but wants to provide a more holistic view of the traffic impacts, said the CAA’s Teresa Di Felice.

“This is not just one artery we’re talking about. The impact to the overall transportation system in the core, that area is going to be challenged, and it’s based on some assumptions that we still don’t know are going to exist. How are we going to look at safety, how are we going to look at all these types of highway-type traffic that are dealing with things like GO buses, school buses, truck traffic or industry, going to be dispersed onto other routes that weren’t designed to handle that type of traffic?” she said.

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Unlike other reports, the Gardiner Coalition doesn’t factor in unapproved, unfunded transit improvements such as the downtown relief line or new LRTs that could mitigate longer drive times, she said. Even if new transit is built, it would probably not appear until around 2031, years after the Gardiner would be gone.

Other members of the Gardiner Coalition include the Canadian Courier & Logistics Association, the Ontario Trucking Association, Redpath Sugar and the Toronto Industry Network.

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