Turns out that TransLink provides weekly updates on the Pattullo Bridge traffic counts – with some attractive charts if you’re into that kind of thing:
And if you are, there’s plenty more where that come from – here.
Upshot: There’s lots of variation in the counts, but overall, traffic seems to be up 5 to 7 percent post Port Mann Bridge opening.
That’s probably a small but perceptible change to drivers, given that the use of bridge is maxxed out at rush hours. But not high enough to suggest the leakage will have a negative impact on the expected numbers for Port Mann – unless there’s been a drop-off of traffic crossing the Fraser.