Don’t rush to rip it down

Debate over Toronto’s much-loathed Gardiner Expressway is now being framed like this: Should the city spend an extra $458 million on this elevated route just to keep a few drivers from having two or three minutes added to their commute?

Most taxpayers would probably answer “no,” and for understandable reasons. But a more relevant question concerns how far this traffic prediction can be trusted. And what are the risks if the forecast is wrong — if Toronto’s already crushing gridlock worsens significantly with removal of the Gardiner east of Jarvis St.?

There’s no doubt congestion will increase under a plan to tear down this section of the Gardiner and replace it with an eight-lane, street-level boulevard. An official study done last year estimated that east-end drivers’ travel time, for the morning commute, would lengthen by five to 10 minutes, depending on their route.

This was widely considered to be too onerous, amounting to as much as 10 to 20 extra minutes stuck in traffic every day. (Bear in mind, this delay would be specifically due to the Gardiner’s removal. Overall travel times are set to increase no matter what.)

Planners were instructed go back and consider measures to “mitigate congestion concerns.” They issued a fresh report on Wednesday pegging anticipated delays during the morning commute, with the Gardiner gone, at just three to five minutes. City officials said the reduced estimate was reached after factoring in better co-ordination of traffic signals and some lane adjustments.

They stressed that they used the best available methodology and, no doubt, they’re right. The problem is that even the best forecast of traffic flow on this scale is necessarily fraught with uncertainty. Many variables can potentially affect these calculations; it’s impossible to account for them all. And small changes can have big impacts — witness the dramatic reduction in anticipated delay attributed to improved signals and lanes.

Analysts used traffic data from 2009, projected forward to 2031, and applied it to the option of removing the Gardiner; repairing and maintaining the existing structure, and a “hybrid” proposal to realign some of the expressway’s ramps and install a boulevard. It was found that the hybrid would leave most east-end drivers unaffected, since the expressway would remain in place, but would cost about $458 million more than going without the Gardiner.

It’s worth noting that this is the cost of construction, maintenance and repair projected over 100 years. Looked at another way, building and operating the hybrid option would involve an extra lifecycle cost of less than $4.6 million a year.

That doesn’t seem too much to pay for peace of mind — for some assurance that the 5,700 motorists who use this section of the Gardiner today, during the morning rush hour alone, won’t face intolerable delays. They won’t be the only ones affected if sunny traffic forecasts aren’t borne out.

The updated analysis shows that tearing down the eastern section of the Gardiner would have a ripple effect, slowing movement elsewhere on the expressway. This isn’t about just a few Scarborough drivers. West-end motorists travelling downtown would also experience delays. Drivers from the Kipling and Lake Shore area, for example, can expect an extra three minutes added to their commute — assuming the official forecast is correct. It could turn out to be more. The hybrid solution would leave them unaffected.

Given what’s at stake, it makes sense to proceed with care, making every effort to reduce Toronto’s already-severe congestion instead of knowingly increasing it by tearing down the Gardiner.

The problem is that even the best forecast of traffic flow on this scale is fraught with uncertainty