There are 5,000 to 6,000 fewer cars a day on the bridge, compared to traffic prior to the toll being introduced a year ago, said Todd Stone.
"There is no question that the Port Mann bridge, the overall traffic volumes are down somewhat year over year," Stone said.
But the drop is expected to be temporary, he said.
"What we've seen in other jurisdictions is a three- to four-month period where volumes may dip a little bit," Stone said, adding that volumes are down about three per cent.
"But we expect is that those numbers will bounce back as people really sort it out, and determine: how much is their time worth?"
Revenue forecasts for the next three years are being adjusted to 20 per cent lower than first anticipated: to $144 million for fiscal 2014, $159 million for 2015 and $174 million for 2016.
Still, the province is on track to pay off the cost of the new bridge ahead of the 2050 schedule, Stone said.
The toll doubled to $3 per crossing last month and critics such as the Canadian Taxpayers Federation say drivers are finding other routes to get to work.
The minister said construction along Highway 1 decreased traffic even before tolls were introduced, and some drivers are waiting until construction is complete throughout the corridor before returning.
High gas prices, improved public transit and more people working from home have also affected traffic on the route, Stone said.
There has also been a major global economic recession since the original forecasts were made, he said.
The new forecast for vehicle traffic on the Port Mann is 100,000 vehicles a day.
Metro Vancouver traffic patterns show no mass diversion of vehicles from the toll bridge to other bridges, Stone said, contrary to complaints from officials in New Westminster, who have said the neighbouring Pattullo bridge is bearing the brunt of a commuter exodus.
Jordan Bateman of the Canadian Taxpayers Federation in B.C. said the $6 price tag for a round trip has prompted drivers to find alternative routes.
"You have to blame tolls for the drop in traffic. It's illogical not to," Bateman said.
And he doesn't believe traffic will return to the crossing.
"I'm a South Fraser resident and I know from experience that I've dodged the Port Mann bridge at times to save that money," he said.
"I think it's a bit naive to think that these 5,000 or 6,000 cars are going to re-materialize simply because there's backups at the Pattullo."
New Westminster Mayor Wayne Wright said the city's own counters on the main streets show a drastic increase in traffic.
"Those are the factual things that we seem to be seeing here," he said.
Wright said the entire transportation network, from bridges to public transit, needs examination by all stakeholders in the region.
"And how we're going to get to it is by working together, rather than at opposite ends."
Also on HuffPost