The study released by C.D. Howe Institute on Thursday suggests between $1.5 billion to $5 billion should be added to government estimates on the cost of congestion to the Greater Toronto and Hamilton area.
GTHA transportation authority Metrolinx estimates the current cost of congestion in the region at around $6 billion.
That figure includes a $3.3 billion cost from travel delays, increased environmental impact, increased vehicle costs from travel delays and increased chance of collision. The rest of the cost estimate is based on the loss of productive time.
But the new report suggests Metrolinx's figures don't take into account the negative impact of opportunities lost due to congestion.
Those might include necessary skilled workers turning down jobs due to lengthy commutes and businesses being unable to bring employees together for face-to-face sharing of knowledge, the report suggested.
The report also suggests gridlock is stopping people from coming into Toronto and Hamilton for things like ball games, cultural visits and shopping, leading to further lost business opportunities.
"What happens when people don't even bother getting into the car?" asks report author Benjamin Dachis.
"The evidence from around the world — and Canada — makes clear that greater access to nearby economic activity results in people earning a higher income. When congestion stifles these relationships, it threatens the essence of urban living."
When the report's figures are added to existing Metrolinx estimates, GTHA's losses due to congestion could be pegged at between $7.5-11 billion per year.
Metrolinx, for its part, supports the report's findings.
"This C.D. Howe study confirms that there's an urgent need for major transit and transportation improvements in the GTHA," said Metrolinx spokesman Mark Ostler said.
"Doing nothing is not an option."
The report comes as Metrolinx is in the middle of a $50-billion plan to improve transit in the region over the next 25 years.
The report's estimates are based on three kinds of benefits that would be gained by eliminating congestion — being more productive at your own job, finding a job when you don't already have a job and finding a better job.
The report suggests workers who commute longer distances earn more in general, but in the GTHA commuters travelling over 30 kilometres make approximately 20 per cent more than people who commute less than five.
By improving congestion levels, the government would be improving business and cultural growth in areas around the area, the report suggests.
But, the report claims, when modes of travel aren't adequate, people won't travel as far to get better jobs and won't leave their house as much because of the time involved in getting somewhere.
Also on HuffPost